阅读说明：本技术 基于核磁共振弛豫时间的温度灵敏度测量多孔介质的润湿性 (Measuring wettability of porous medium based on temperature sensitivity of nuclear magnetic resonance relaxation time ) 是由 郭亨泰 艾哈迈德·穆巴拉克·阿勒-哈尔比 于 2018-11-28 设计创作，主要内容包括：本公开描述了用于测量岩样的润湿性的方法和系统,包括计算机实现的方法、计算机程序产品和计算机系统。一种方法,包括：在多个温度中的每个温度下,获得具有饱和水平的岩样的第一核磁共振(NMR)表面弛豫时间；基于所述第一NMR表面弛豫时间和对应的温度确定第一温度灵敏度；在所述多个温度中的每个温度下,获得被油饱和的所述岩样的第二NMR表面弛豫时间；基于所述第二NMR表面弛豫时间和对应的温度确定第二温度灵敏度；以及基于所述第一温度灵敏度和所述第二温度灵敏度确定所述岩样的润湿性。(The present disclosure describes methods and systems, including computer-implemented methods, computer program products, and computer systems, for measuring wettability of a rock sample. A method, comprising: obtaining a first Nuclear Magnetic Resonance (NMR) surface relaxation time of the rock sample having a saturation level at each of a plurality of temperatures; determining a first temperature sensitivity based on the first NMR surface relaxation time and a corresponding temperature; obtaining a second NMR surface relaxation time of the rock sample saturated with oil at each of the plurality of temperatures; determining a second temperature sensitivity based on the second NMR surface relaxation time and a corresponding temperature; and determining the wettability of the rock sample based on the first temperature sensitivity and the second temperature sensitivity.)

1. A method for measuring wettability of a rock sample, comprising:

obtaining a first Nuclear Magnetic Resonance (NMR) surface relaxation time of the rock sample having a saturation level at each of a plurality of temperatures;

determining a first temperature sensitivity based on the first NMR surface relaxation time and a corresponding temperature;

obtaining a second Nuclear Magnetic Resonance (NMR) surface relaxation time of the rock sample saturated with oil at each of the plurality of temperatures;

determining a second temperature sensitivity based on the second NMR surface relaxation time and a corresponding temperature; and

determining the wettability of the rock sample based on the first temperature sensitivity and the second temperature sensitivity.

2. The method of claim 1, wherein obtaining the first NMR surface relaxation time comprises:

measuring the NMR relaxation time of the oil;

measuring the NMR relaxation time of the rock sample having the saturation level; and

determining the first NMR surface relaxation time based on an NMR relaxation time of the oil and an NMR relaxation time of the rock sample having the saturation level.

3. The method of claim 2, wherein the first NMR surface relaxation time is determined according to the formula:

wherein, T_1,s,SurfaceRepresents the first NMR surface relaxation time, T_1,O,BulkRepresents the NMR relaxation time of the oil, and T_1,S,ApparentRepresenting N of the rock sample having the saturation levelMR relaxation time.

4. The method of claim 1, wherein the first temperature sensitivity is determined from a slope of a temperature sensitivity map obtained based on the first NMR surface relaxation time and a corresponding temperature.

5. The method of claim 4, wherein the temperature sensitivity map is obtained by converting the first NMR surface relaxation time using a logarithmic scale.

6. The method of claim 4, wherein the wettability of the rock sample is determined according to the formula:

wherein WI represents the wettability of the rock sample, m_{o_w}Represents the first temperature sensitivity, and m_oRepresenting the second temperature sensitivity.

7. The method of claim 1, further comprising:

saturating the rock sample with different saturation levels; and

determining the wettability of the rock sample having the different saturation levels.

8. The method of claim 1, wherein the first NMR surface relaxation time is determined based on at least one of a T1 relaxation time or a T2 relaxation time.

9. The method of claim 8, wherein the first NMR surface relaxation time is determined based on the T1 relaxation time, and the wettability is a first wettability, the method further comprising:

obtaining a third NMR surface relaxation time for the rock sample having a saturation level at each of the plurality of temperatures, wherein the third NMR surface relaxation time is determined based on the T2 relaxation time;

determining a third temperature sensitivity based on the third NMR surface relaxation time and a corresponding temperature;

obtaining a fourth Nuclear Magnetic Resonance (NMR) surface relaxation time of the rock sample saturated with oil at each of the plurality of temperatures, wherein the fourth NMR surface relaxation time is determined based on the T2 relaxation time;

determining a fourth temperature sensitivity based on the fourth NMR surface relaxation time and a corresponding temperature;

determining a second wettability of the rock sample based on the third temperature sensitivity and the fourth temperature sensitivity; and

determining a combined wettability of the rock sample based on the first wettability and the second wettability.

10. The method of claim 1, further comprising:

using heavy water D₂O saturating the rock sample; and

in the utilization of D₂And O, after the rock sample is saturated, injecting oil into the rock sample.

11. The method of claim 10, further comprising:

after injecting oil into the rock sample, aging the rock sample before measuring the NMR relaxation time of the rock sample.

12. A non-transitory computer-readable medium storing instructions that, when executed, cause a computer system to perform operations comprising:

obtaining a first Nuclear Magnetic Resonance (NMR) surface relaxation time of the rock sample having a saturation level at each of a plurality of temperatures;

determining a first temperature sensitivity based on the first NMR surface relaxation time and a corresponding temperature;

obtaining a second Nuclear Magnetic Resonance (NMR) surface relaxation time of the rock sample saturated with oil at each of the plurality of temperatures;

determining a second temperature sensitivity based on the second NMR surface relaxation time and a corresponding temperature; and

determining the wettability of the rock sample based on the first temperature sensitivity and the second temperature sensitivity.

13. The non-transitory computer-readable medium of claim 12, wherein obtaining the first NMR surface relaxation time comprises:

obtaining the NMR relaxation time of the oil;

obtaining an NMR relaxation time of the rock sample having the saturation level; and

determining the first NMR surface relaxation time based on an NMR relaxation time of the oil and an NMR relaxation time of the rock sample having the saturation level.

14. The non-transitory computer-readable medium of claim 13, wherein the first NMR surface relaxation time is determined according to the formula:

wherein, T_1,s,SurfaceRepresents the first NMR surface relaxation time, T_1,O,BulkRepresents the NMR relaxation time of the oil, and T_1,S,ApparentRepresenting the NMR relaxation time of the rock sample having the saturation level.

15. The non-transitory computer-readable medium of claim 12, wherein the first temperature sensitivity is determined from a slope of a temperature sensitivity map obtained based on the first NMR surface relaxation time and a corresponding temperature.

16. The non-transitory computer-readable medium of claim 15, wherein the temperature sensitivity map is obtained by converting the first NMR surface relaxation time using a logarithmic scale.

17. The non-transitory computer-readable medium of claim 12, wherein the wettability of the rock sample is determined according to the formula:

wherein WI represents the wettability of the rock sample, m_{o_w}Represents the first temperature sensitivity, and m_oRepresenting the second temperature sensitivity.

18. The non-transitory computer-readable medium of claim 12, wherein the first NMR surface relaxation time is determined based on at least one of a T1 relaxation time or a T2 relaxation time.

19. A system, comprising:

a Nuclear Magnetic Resonance (NMR) instrument configured to, at each of a plurality of temperatures:

measuring the NMR relaxation time of the oil;

measuring the NMR relaxation time of a rock sample having a saturation level; and

measuring the NMR relaxation time of the oil-saturated rock sample;

a computer system connected to the NMR instrument, wherein the computer system comprises:

at least one hardware processor; and

a non-transitory computer-readable storage medium coupled to the at least one hardware processor and storing programming instructions for execution by the at least one hardware processor, wherein the programming instructions, when executed, cause the at least one hardware processor to perform operations comprising:

determining a first NMR surface relaxation time of the rock sample having the saturation level based on an NMR relaxation time of oil and an NMR relaxation time of the rock sample having the saturation level at each of the plurality of temperatures;

determining a first temperature sensitivity based on the first NMR surface relaxation time and a corresponding temperature;

determining a second NMR surface relaxation time of the rock sample saturated with oil based on the NMR relaxation time of the oil and the NMR relaxation time of the rock sample saturated with oil at each of the plurality of temperatures;

determining a second temperature sensitivity based on the second NMR surface relaxation time and a corresponding temperature; and

determining the wettability of the rock sample based on the first temperature sensitivity and the second temperature sensitivity.

20. The system of claim 19, wherein the wettability of the rock sample is determined according to the formula:

wherein WI represents the wettability of the rock sample, m_{o_w}Represents the first temperature sensitivity, and m_oRepresenting the second temperature sensitivity.

Technical Field

The present disclosure relates to the exploration and production of hydrocarbons, and more particularly to measuring rock wettability using Nuclear Magnetic Resonance (NMR).

Background

Rock in a hydrocarbon reservoir may store hydrocarbons (e.g., oil, gas, or any combination thereof) by trapping the hydrocarbons within a porous formation in the rock. Thus, a measure of the wettability of rock in the reservoir may be used to determine the potential productivity of the reservoir. Wettability may also be used to optimize the extraction of stored hydrocarbons from a reservoir during various steps of a production operation, such as waterflooding and Enhanced Oil Recovery (EOR).

Disclosure of Invention

The present disclosure describes methods and systems, including computer-implemented methods, computer program products, and computer systems, for measuring rock wettability. A method for measuring wettability of a rock sample, comprising: obtaining a first Nuclear Magnetic Resonance (NMR) surface relaxation time of the rock sample having a saturation level at each of a plurality of temperatures; determining a first temperature sensitivity based on the first NMR surface relaxation time and a corresponding temperature; obtaining a second Nuclear Magnetic Resonance (NMR) surface relaxation time of the rock sample saturated with oil at each of the plurality of temperatures; determining a second temperature sensitivity based on the second NMR surface relaxation time and a corresponding temperature; and determining the wettability of the rock sample based on the first temperature sensitivity and the second temperature sensitivity.

Other embodiments of this aspect include: corresponding computer systems, apparatus, and computer programs, each configured to perform the actions of the methods, recorded on one or more computer storage devices. The system of one or more computers may be configured to: certain operations or actions may be performed by software, firmware, hardware, or a combination of software, firmware, or hardware installed on the system that, when operated, causes the system to perform the actions. The one or more computer programs may be configured to: certain operations or actions are performed by virtue of including instructions that, when executed by a data processing apparatus, cause the apparatus to perform the actions.

The details of one or more implementations of the subject matter of this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims.

Drawings

Fig. 1 is a schematic diagram of a system for determining wettability of a reservoir rock sample based on Nuclear Magnetic Resonance (NMR) relaxation times, according to an embodiment.

Fig. 2 is an example of a process for measuring wettability of a reservoir rock sample based on NMR surface relaxation times, according to an embodiment.

Fig. 3 is a diagram illustrating an example graph of NMR surface relaxation time versus temperature according to an embodiment.

Fig. 4 is a graph illustrating an example comparison of temperature sensitivity of different NMR surface relaxation times according to an embodiment.

FIG. 5 illustrates an example wettability determination method according to an embodiment.

FIG. 6 is a high level architectural block diagram of a wettability analysis system according to an embodiment.

Like reference numbers and designations in the various drawings indicate like elements.

Detailed Description

The following description is presented to enable any person skilled in the art to make and use the disclosed subject matter, and is provided in the context of one or more specific embodiments. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined by the disclosure may be applied to other embodiments and applications without departing from the scope of the disclosure. Thus, the present disclosure is not intended to be limited to the embodiments shown or described, but is to be accorded the widest scope consistent with the principles and features disclosed in the present disclosure.

The present disclosure generally describes methods and systems, including computer-implemented methods, computer program products, and computer systems, for measuring rock wettability. One technique for understanding the characteristics of hydrocarbon reservoirs is to develop a computer-generated software model of all or part of the reservoir. To develop such a model, a reservoir rock sample from a hydrocarbon reservoir is evaluated and the results of the evaluation are provided as input to a computer software program that generates a software model. Reservoir rock samples may be evaluated by performing one or more of several experiments under laboratory conditions or under reservoir conditions (i.e., conditions experienced by samples in a hydrocarbon reservoir). Rock wettability, in particular the wettability of porous structures within the rock, is one of the parameters of reservoir rock samples that can be evaluated.

Wetting is the ability of a liquid to remain in contact with a solid surface due to intermolecular interactions when the two materials are brought together. Wettability, which measures the degree of wetting, is the product of a force balance between adhesion and cohesion. Adhesion is the tendency of liquid molecules to create attraction forces on different substances. Cohesion, on the other hand, results in the smallest surface area possible for the droplets. The hydrophobicity of the solid surface is caused by the adhesion between the liquid and the solid. Thus, the wettability of solid surfaces is directly related to hydrophobicity. In the present disclosure, wettability studies are described in the context of reservoir rock samples, i.e., rock samples that may be found in a hydrocarbon reservoir and may trap hydrocarbons in its pore system. The research and discovery described in this disclosure may be applicable to any type of porous media, including, for example, homogeneous pore systems (i.e., pores having substantially the same size) or heterogeneous pore systems (i.e., porous subsystems having all different sizes).

Wettability can be used as a distinguishing feature of reservoir rock that designates the rock as hydrophobic or hydrophilic. Wettability is a material parameter characteristic of a given rock (e.g., sandstone or carbonate) and also depends on factors such as surface roughness, surface size, the presence of major adsorption sites, and specific ionic effects. Rock wettability is one of the parameters that influence the flow of fluid through the rock. Rock wettability is therefore an input variable for a geophysical model used to predict flow through reservoir rock. One technique for determining the wettability of a surface (i.e., the ability of a surface to retain moisture) is to add a drop of water to a surface and measure the contact angle of the water on the surface. The determined wettability may be provided as an input variable to a (computer-generated or other) geophysical model. If the wettability of the porous structure of the actual rock, for example under conditions similar and simulating a rock environment, is determined, the input variables will be more accurate and the prediction of the geophysical model will be more accurate. In addition, rock wettability at different saturation levels is one of the important factors for the prediction of oil and gas production due to the dynamic nature of pore surface wettability during injection of various types of fluids. One is the change in wettability during water flooding. As more water is introduced into the reservoir, the pore surfaces become more hydrophilic as a large amount of hydrocarbon components that attach to the pore surfaces are replaced by the injected water. Therefore, measuring wettability at different saturation levels is useful in predicting hydrocarbon production.

In some embodiments, wettability may be measured based on Nuclear Magnetic Resonance (NMR) surface relaxation times. The NMR surface relaxation time can be defined by the following formula:

wherein T is_sRepresents NMR surface relaxation time, ρ represents surface relaxation rate, S represents total pore surface area, and V represents total pore volume. NMR surface relaxation times include the equation denoted T_1,sAnd is denoted as T1 surface relaxation time_2,sT2 surface relaxation time. T can be calculated based on the relaxation times observed in NMR measurements using the following formula_1,sAnd T_2,s：

Wherein₀And₀represents the T1 and T2 relaxation times, respectively, observed during NMR measurements; t is_1,bAnd T_1,sRespectively representing the volume and surface relaxation times of T1; t is_2,b、T_2,sAnd T_2,DRespectively, the volume, surface and diffusion relaxation times of T2. The T1 and T2 relaxation times may also be referred to as the T1 and T2 apparent relaxation times, respectively. NMR measurements are sensitive to wettability because solid surfaces have the effect of promoting magnetic relaxation of saturated fluids. The magnitude of this effect may depend on the wettability characteristics of the solid with respect to the liquid in contact with the surface. Thus, the surface relaxation time T_1,sAnd T_2,sMainly determined by the strength of the fluid-rock interaction.

In addition to fluid-rock interactions, temperature is also a factor in NMR surface relaxation time. The following equation shows the relationship between temperature and NMR surface relaxation time:

wherein

And

respectively at temperatures Ta and T_bThe T1 and T2 surface relaxation times obtained Δ E represent the surface activation energy, which is determined by the properties of the fluid and the pore surfaces of the rock R represents the gas constant, which is 1.99 × 10-3 kcal/kmol.

Pore surfaces with different Δ Ε values relative to a particular fluid may have different NMR surface relaxation time temperature sensitivities. Since Δ E is fixed for a particular fluid and solid pore surface. Thus, wettability can be measured by the temperature sensitivity of NMR surface relaxation time. If the NMR surface relaxation time is plotted against temperature, the wettability of the surface can be determined based on the slope of the plot. For a pore surface that is 100% hydrophilic, the slope is 0 since there is no relaxation (relax) of the oil at the surface. On the other hand, for a 100% oleophilic surface, the slope is a non-zero value determined by the Δ Ε value. Thus, the wettability of a particular water-saturated pore surface can be quantified by comparing the slope of a sample based on 100% oil saturation with a sample saturated with a particular amount of water-saturated oil. This method provides a non-destructive and non-invasive measurement method for rock samples. Fig. 1-6 provide additional details of these embodiments.

Fig. 1 is a schematic diagram of a system 100 for determining wettability of a reservoir rock sample based on NMR relaxation times, in accordance with an embodiment. The system 100 includes an NMR instrument 110 connected to an analyzer 120 and a water line 130. NMR instrument 110 represents an NMR instrument configured to measure NMR relaxation times. Examples of NMR instruments include low magnetic field NMR instruments. In some embodiments, the NMR instrument 110 may include an NMR controller 102 connected to one or more NMR magnets (e.g., the first NMR magnet 104a or the second NMR magnet 104b, or both). In some cases, especially for porous media samples with high permeability, fluid redistribution over a range of temperatures during NMR measurements may cause experimental errors. For these types of samples, additional external magnets with high magnetic fields can be used to shorten the NMR data acquisition time.

The NMR instrument 110 also includes an NMR sample cell 122. NMR sample cell 122 is configured to maintain High Pressure and High Temperature (HPHT) conditions. For example, the NMR sample cell 122 may withstand a maximum of 15,000 pounds Per Square Inch (PSI) and up to 250 degrees Celsius (C.) for samples less than 5 millimeters (mm) in diameter, and a maximum of 5,000PSI and up to 150℃ for samples about 1.5 inches in diameter. Sample 112 is placed in NMR sample cell 122 for measurement. Sample 112 may be a porous medium of any shape that may fit into NMR sample cell 122. For example, the sample 112 may be a core plug or a rock fragment. The NMR controller 102 controls the NMR instrument. For example, the NMR controller 102 may provide instructions to the NMR instrument to measure relaxation times at different temperatures. The NMR controller 102 may also receive measurements of relaxation times.

The system 100 also includes an analyzer 120. Analyzer 120 may implement computer software operations to determine the wettability of sample 112 based on the measured relaxation times. In some implementations, the analyzer 120 and the NMR controller 102 can be implemented as different computing devices. Alternatively, the NMR controller 102 and the analyzer 120 may be implemented as a single entity.

Water line 130 provides circulating fluid to NMR sample cell 122. The circulating fluid may be water, oil or other liquid. The water line 130 may include other components, such as a pump, a gauge, a reservoir that may contain and inject a fluid, or any combination thereof. The water pipe 130 is connected to a heater 132. The heater 132 may heat the circulating fluid in the water pipe 130. The heater 132 may be set at different temperatures for different NMR measurements.

Fig. 2 is an example of a process 200 for measuring wettability of a reservoir rock sample based on NMR surface relaxation times, according to an embodiment. For clarity of presentation, the following description generally describes process 200 in the context of fig. 1 and 3-6. However, it should be understood that process 200 may be performed, for example, by any other suitable system, environment, software, and hardware, or combination of systems, environments, software, and hardware, where appropriate. In some embodiments, the steps of process 200 may be performed in parallel, in combination, in a loop, or in any order.

At 202, NMR relaxation times of bulk oil are measured at different temperatures. In some cases, the measured temperature range is between 15 ℃ and 85 ℃. For each temperature, the relaxation time (T) of the bulk oil can be recorded_1,O,BulkAnd T_2,O,Bulk). In some embodiments, NMR relaxation times can be obtained using HPHT NMR probes. The temperature of the sample can be controlled by circulating an inert fluid that does not generate an NMR signal. By varying the temperature of the circulating fluid using the heater, the measured temperature can be varied accordingly.

At 204, the porous media sample is saturated with water. Can collect porous medium from the storage partAnd (4) sampling the quality sample. A core flooding system may be used to saturate the porous media sample. In some embodiments, the heavy water (D) is₂O) is used to saturate the porous media sample. D₂O is chemically equivalent to ordinary water (H)₂O), but for hydrogen: (¹H) The NMR signal was not visible. Thus, the use of heavy water can isolate the NMR signal generated by the oil within the sample.

At 206, the bulk oil measured at 202 is injected into the saturated porous media sample. Bulk oil is injected to produce a porous media sample at saturation level S. The saturation level S is the ratio between the saturated volume of oil and the total pore volume. The saturation level S may take a value between 0 and 100%. The saturation level S can be achieved by controlling the amount of bulk oil injected into the sample and monitoring the saturation level until it reaches the value S. The saturation level can be monitored by using NMR/Magnetic Resonance Imaging (MRI) or by volumetric analysis of the effluent of core flooding.

At 208, the sample being injected is aged over a period of time. The aging process causes the oil to fully adhere to the pore surfaces. In some embodiments, the length of the aging period may be determined based on NMR relaxation time measurements. The aging period may be terminated if the NMR relaxation time is stable. The aging time may vary for different samples. For example, the aging period may vary between 2 weeks and 6 weeks. In some cases, the aging time may be four weeks. In some cases, the sample may be aged by storage in a core flood column at reservoir temperature and pressure.

At 210, the NMR relaxation time of the saturated pore media sample is measured at the same temperature as step 202. For each temperature, the relaxation time (T) of a saturated pore media sample can be recorded_1,S,ApparentAnd T_2,S,Apparent)。

At 212, for each temperature, based on the bulk oil relaxation time measured at step 202 and the saturated pore media sample relaxation time measured at step 210, the NMR surface relaxation time is calculated using the following formula:

wherein T is_1,S,SurfaceAnd T_2,S,surfaceT1 and T2 surface relaxation times representing the calculated saturation level S.

At 214, the NMR surface relaxation times may be plotted for different temperatures. FIG. 3 is a diagram 300 illustrating an exemplary plot of NMR surface relaxation time versus temperature in accordance with an embodiment. The data points in the graph 300 were obtained in laboratory experiments. The x-axis of the graph 300 represents temperature in degrees celsius at each measurement. The y-axis of the plot 300 represents the NMR surface relaxation time calculated at step 212. The y-axis uses a logarithmic scale (logarithmic scale) in microseconds (ms). Points 302 and 304 represent T at 30 ℃ and 40 ℃ respectively_1,S,Surface. Line 310 represents T_1,S,SurfaceLinear with temperature. T based on different temperatures_2,S,SurfaceA similar straight line can be obtained.

At 216, the pore media sample is cleaned and fully saturated with bulk oil as measured at 202.

At 218, the pore media sample saturated with oil is aged over a period of time. Similar to step 208, the length of the aging period may be determined based on NMR relaxation time measurements. The aging period may be terminated if the NMR relaxation time is stable. The aging time may vary for different samples. For example, the aging period may vary between 2 weeks and 6 weeks. In some cases, the aging time is 4 weeks.

At 220, the NMR relaxation time of the saturated pore media sample is measured at the same temperature as in step 202. For each temperature, the relaxation time (T) of a saturated pore media sample can be recorded_1,O,ApparentAnd T_2,O,Apparent)。

At 222, for each temperature, based on the bulk oil relaxation time measured at step 202 and the saturated pore media sample relaxation time measured at step 220, the NMR surface relaxation time of the oil saturated sample is calculated using the following formula:

wherein T is_1,O,SurfaceAnd T_2,O,SurfaceRepresenting the first saturation level S, the calculated T1 and T2 surface relaxation times of the samples fully saturated with oil.

At 224, the NMR surface relaxation times obtained at 222 may be plotted for different temperatures.

At 226, the temperature sensitivities of the NMR surface relaxation times of the sample saturated at the first saturation level and the sample fully saturated with oil may be compared to determine the wettability index. Fig. 4 is a graph 400 illustrating an example comparison of temperature sensitivity for different NMR surface relaxation times, according to an embodiment. The data points in the graph 400 were obtained in laboratory experiments. The x-axis of the graph 400 represents the temperature in degrees celsius at which each measurement is taken. The line 410 represents the temperature sensitivity of the NMR surface relaxation time of a sample saturated at the saturation level S. The straight line 410 has a slope M _{O_W}2, which represents the temperature sensitivity of the NMR surface relaxation time of the sample at the first saturation level S. Line 420 represents the temperature sensitivity of the NMR surface relaxation time of a sample fully saturated with oil. The straight line 420 has a slope M_OIt represents the temperature sensitivity of the NMR surface relaxation time of a sample fully saturated with oil.

Thus, the following formula may be used based on M_{O_W}And M_ODetermining the Wettability Index (WI):

thus, in the example shown, the WI of the sample is 2/5 ═ 0.4. The value of WI represents the wettability of the porous medium sample at saturation level S. In some operations, the process 200 may be repeated more than one iteration. At each iteration, a different saturation level S is selected at step 206. Accordingly, the WI for each of these different saturation levels may be determined at step 226 of the corresponding iteration. Different saturation levels of WI can be used to generate the relative permeability curve. The relative permeability curve represents the petrophysical properties of rock in the reservoir from which the porous medium sample was collected and can be used to predict hydrocarbon productivity of the reservoir. Furthermore, these WI's may be used in Enhanced Oil Recovery (EOR) and enhanced oil recovery (IOR) processes for developing reservoirs.

As previously described, both NMR surface relaxation times T1 and T2 may produce temperature sensitivity maps. Thus, the wettability index may be obtained based on the temperature sensitivity of the NMR surface relaxation time T1 or the NMR surface relaxation time T2, respectively. In some cases, the two wettability indices may be combined, e.g., averaged, to obtain a combined wettability index. This approach may provide more robust measurements.

FIG. 5 illustrates an example wettability determination method 500 according to an embodiment. For clarity of presentation, the following description generally describes method 500 in the context of fig. 1-4 and 6. However, it should be understood that method 500 may be performed, for example, by any other suitable system, environment, software, and hardware, or combination of systems, environments, software, and hardware, where appropriate. In some cases, method 500 may be performed on a large-scale computer cluster, a supercomputer, or any other computing device or collection of computing devices. In some embodiments, the steps of method 500 may be performed in parallel, in combination, in a loop, or in any order.

At 502, at each of a plurality of temperatures, a first Nuclear Magnetic Resonance (NMR) surface relaxation time of a rock sample having a saturation level is obtained. At 504, a first temperature sensitivity is determined based on the first NMR surface relaxation time and the corresponding temperature. At 506, a second NMR surface relaxation time of the oil-saturated rock sample is obtained at each of the plurality of temperatures. At 508, a second temperature sensitivity is determined based on the second NMR surface relaxation time and the corresponding temperature. At 510, wettability of the rock sample is determined based on the first temperature sensitivity and the second temperature sensitivity. At 512, the rock sample is injected at different saturation levels, and step 502-510 is repeated to determine the wettability of the rock sample having different saturation levels.

Fig. 6 is a high-level architectural block diagram of a wettability analysis system 600 that analyzes wettability based on the methods described in the present disclosure, according to an embodiment. From a high level, the illustrated system 600 includes a computer 602 coupled to a network 630.

The depicted illustration is only one possible implementation of the described subject matter and is not intended to limit the disclosure to the single depicted implementation. One of ordinary skill in the art will recognize that the components described may be connected, combined, or used in an alternative manner consistent with the present disclosure.

Network 630 facilitates communication between computer 602 and other components (e.g., components that obtain observation data for a location and send observation data to computer 602). The network 630 may be a wireless or wired network. The network 630 may also be a memory pipe, a hardware connection, or any internal or external communication path between components.

The computer 602 comprises a computing system configured to perform a method as described in this disclosure. For example, the computer 602 may be used to implement the NMR controller 102 and analyzer 120 shown in FIG. 1. In some cases, the algorithm may be implemented in executable computing code (e.g., C/C + + executable code). In some cases, the computer 602 may include a stand-alone LINUX system running a batch application. In some cases, computer 602 may comprise a mobile or personal computer.

The computer 602 may include a computer that includes input devices (e.g., a keypad, keyboard, touch screen, microphone, voice recognition device, other devices that can accept user information) or output devices that convey information associated with the operation of the computer 602, including numerical data, visual or audio information, or a Graphical User Interface (GUI).

The computer 602 may serve as a client, a network component, a server, a database or other persistent device, or any other component of the system 600. In some implementations, one or more components of the computer 602 may be configured to operate in a cloud-computing-based environment.

At a high level, the computer 602 is an electronic computing device operable to receive, transmit, process, store, or manage data and information associated with the system 600. According to some embodiments, computer 602 may also include or be communicatively coupled with an application server, an email server, a web server, a cache server, a streaming data server, a Business Intelligence (BI) server, or other server.

The computer 602 may receive requests from client applications (e.g., applications executing on another computer 602) over the network 630 and respond to the requests by processing the received requests in an appropriate software application. Additionally, requests can also be sent to the computer 602 from internal users (e.g., from a command console), external or third parties, or other automated applications.

Each of the components of the computer 602 may communicate using a system bus 603. In some embodiments, any or all of the components (both hardware and software) of the computer 602 may interface with each other or the interface 604 via the system bus 603 using an Application Programming Interface (API)612 or a services layer 613. The API 612 may include specifications for routines, data structures, and object classes. API 612 may be independent or dependent on the computer language and may refer to a complete interface, a single function, or even a set of APIs. Service layer 613 provides software services to computer 602 or system 600. The functionality of the computer 602 may be accessible to all service consumers using the service layer. Software services (e.g., provided by the services layer 613) provide reusable, defined business functions through defined interfaces. For example, the interface may be software written in JAVA, C + +, or a suitable language that provides data in an extensible markup language (XML) format. While shown as an integrated component of computer 602, alternative embodiments may show API 612 or service layer 613 as a separate component from other components of computer 602 or system 600. Further, any or all portions of the API 612 and services layer 613 may be implemented as sub-modules of another software module, enterprise application, or hardware module without departing from the scope of this disclosure.

The computer 602 includes an interface 604. Although shown in fig. 6 as a single network interface 604, two or more interfaces 604 may be used according to particular needs, desires, or particular implementations of the computer 602 or system 600. Interface 604 is used by computer 602 to communicate with other systems, whether shown or not, in a distributed environment (including within system 600) connected to network 630. In general, the interface 604 includes logic encoded in software or hardware in a suitable combination and operable to communicate with the network 630. More specifically, interface 604 may include software that supports one or more communication protocols associated with communications such that network 630 or the interface's hardware is operable to communicate physical signals both internal and external to system 600 as shown.

The computer 602 includes a processor 605. Although illustrated in fig. 6 as a single processor 605, two or more processors may be used depending on the particular needs, desires, or particular implementation of the computer 602 or system 600. In general, the processor 605 executes instructions and manipulates data to perform the operations of the computer 602. In particular, the processor 605 performs the functions required for processing geophysical data.

The computer 602 also includes memory 608 that holds data for the computer 602 or other components of the system 600. Although illustrated in fig. 6 as a single memory 608, two or more memories may be used depending on the particular needs, desires, or particular implementation of the computer 602 or system 600. Although the memory 608 is shown as an integrated component of the computer 602, in alternative embodiments, the memory 608 may be external to the computer 602 or system 600.

The application 607 is a software engine that provides functionality according to the particular needs, desires, or particular implementations of the computer 602 or system 600, particularly with respect to functionality required for processing geophysical data. For example, the application 607 may serve as one or more of the components or applications described in fig. 1-5. Further, although shown as a single application 607, the application 607 may be implemented as multiple applications 607 on the computer 602. Additionally, although shown as being integrated with computer 602, in alternative embodiments, application 607 may be external to computer 602 or system 600.

There may be any number of computers 602 associated with or external to the system 600 and communicating via the network 630. Moreover, the terms "client," "user," and other suitable terms may be used interchangeably, as appropriate, without departing from the scope of the present disclosure. Further, the present disclosure contemplates that many users may use one computer 602, or that one user may use multiple computers 602.

Implementations of the described subject matter may include one or more features, either alone or in combination.

For example, in a first embodiment, a method for measuring wettability of a rock sample, comprises: obtaining a first Nuclear Magnetic Resonance (NMR) surface relaxation time of the rock sample having a saturation level at each of a plurality of temperatures; determining a first temperature sensitivity based on the first NMR surface relaxation time and a corresponding temperature; obtaining a second Nuclear Magnetic Resonance (NMR) surface relaxation time of the rock sample saturated with oil at each of the plurality of temperatures; determining a second temperature sensitivity based on the second NMR surface relaxation time and a corresponding temperature; and determining the wettability of the rock sample based on the first temperature sensitivity and the second temperature sensitivity.

The foregoing and other embodiments may each optionally include, alone or in combination, one or more of the following features:

in a first aspect combinable with general embodiments, wherein obtaining the first NMR surface relaxation time comprises: measuring the NMR relaxation time of the oil; measuring the NMR relaxation time of the rock sample having the saturation level; and determining the first NMR surface relaxation time based on the NMR relaxation time of the oil and the NMR relaxation time of the rock sample having the saturation level.

A second aspect combinable with any of the preceding or following aspects, wherein the first NMR surface relaxation time is determined according to the following equation:

wherein, T_1,s,SurfaceRepresents the first NMR surface relaxation time, T_1,O,BulkRepresents the NMR relaxation time of the oil, and T_1,S,ApparentRepresenting the NMR relaxation time of the rock sample having the saturation level.

A third aspect combinable with any of the preceding or following aspects, wherein the first temperature sensitivity is determined from a slope of a temperature sensitivity map obtained based on the first NMR surface relaxation time and a corresponding temperature.

A fourth aspect combinable with any of the preceding or following aspects, wherein the temperature sensitivity map is obtained by converting the first NMR surface relaxation time using a logarithmic scale.

A fifth aspect combinable with any of the preceding or following aspects, wherein the wettability of the rock sample is determined according to the formula:

wherein WI represents the wettability of the rock sample, m_{o_w}Represents the first temperature sensitivity, and m_oRepresenting the second temperature sensitivity.

A sixth aspect combinable with any of the preceding or following aspects, the method further comprising: saturating the rock sample with different saturation levels; and determining the wettability of the rock sample having the different saturation levels.

A seventh aspect combinable with any of the preceding or following aspects, wherein the first NMR surface relaxation time is determined based on at least one of a T1 relaxation time or a T2 relaxation time.

An eighth aspect combinable with any of the preceding or following aspects, wherein the first NMR surface relaxation time is determined based on a T1 relaxation time, and the wettability is a first wettability, the method further comprising: obtaining a third NMR surface relaxation time for the rock sample having a saturation level at each of the plurality of temperatures, wherein the third NMR surface relaxation time is determined based on the T2 relaxation time; determining a third temperature sensitivity based on the third NMR surface relaxation time and a corresponding temperature; obtaining a fourth Nuclear Magnetic Resonance (NMR) surface relaxation time of the rock sample saturated with oil at each of the plurality of temperatures, wherein the fourth NMR surface relaxation time is determined based on the T2 relaxation time; determining a fourth temperature sensitivity based on the fourth NMR surface relaxation time and a corresponding temperature; determining a second wettability of the rock sample based on the third temperature sensitivity and the fourth temperature sensitivity; and determining a combined wettability of the rock sample based on the first wettability and the second wettability.

A ninth aspect combinable with any of the preceding or following aspects, the method further comprising: using heavy water (D)₂O) saturating the rock sample; and in the utilization of D₂And O, after the rock sample is saturated, injecting oil into the rock sample.

A tenth aspect combinable with any of the preceding or following aspects, the method further comprising: after injecting oil into the rock sample, aging the rock sample before measuring the NMR relaxation time of the rock sample.

In a second embodiment, a non-transitory computer-readable medium storing instructions that, when executed, cause a computer to perform operations comprising: obtaining a first Nuclear Magnetic Resonance (NMR) surface relaxation time of the rock sample having a saturation level at each of a plurality of temperatures; determining a first temperature sensitivity based on the first NMR surface relaxation time and a corresponding temperature; obtaining a second Nuclear Magnetic Resonance (NMR) surface relaxation time of the rock sample saturated with oil at each of the plurality of temperatures; determining a second temperature sensitivity based on the second NMR surface relaxation time and a corresponding temperature; and determining the wettability of the rock sample based on the first temperature sensitivity and the second temperature sensitivity.

The foregoing and other embodiments may each optionally include, alone or in combination, one or more of the following features:

in a first aspect combinable with general embodiments, wherein obtaining the first NMR surface relaxation time comprises: measuring the NMR relaxation time of the oil; measuring the NMR relaxation time of the rock sample having the saturation level; and determining the first NMR surface relaxation time based on the NMR relaxation time of the oil and the NMR relaxation time of the rock sample having the saturation level.

A second aspect combinable with any of the preceding or following aspects, wherein the first NMR surface relaxation time is determined according to the following equation:

wherein, T_1,s,SurfaceRepresents the first NMR surface relaxation time, T_1,O,BulkRepresents the NMR relaxation time of the oil, and T_1,S,ApparentRepresenting the NMR relaxation time of the rock sample having the saturation level.

A third aspect combinable with any of the preceding or following aspects, wherein the first temperature sensitivity is determined from a slope of a temperature sensitivity map obtained based on the first NMR surface relaxation time and a corresponding temperature.

A fourth aspect combinable with any of the preceding or following aspects, wherein the temperature sensitivity map is obtained by converting the first NMR surface relaxation time using a logarithmic scale.

A fifth aspect combinable with any of the preceding or following aspects, wherein the wettability of the rock sample is determined according to the formula:

wherein WI represents the wettability of the rock sample, m_{o_w}Represents the first temperature sensitivity, and m_oRepresenting the second temperature sensitivity.

A sixth aspect combinable with any of the preceding or following aspects, wherein the first NMR surface relaxation time is determined based on at least one of a T1 relaxation time or a T2 relaxation time.

In a third embodiment, a system comprises: a Nuclear Magnetic Resonance (NMR) instrument configured to, at each of a plurality of temperatures: measuring the NMR relaxation time of the oil; measuring the NMR relaxation time of a rock sample having a saturation level; and measuring the NMR relaxation time of the oil-saturated rock sample; a computer system connected to the NMR instrument, wherein the computer system comprises: at least one hardware processor; and a non-transitory computer-readable storage medium coupled to the at least one hardware processor and storing programming instructions for execution by the at least one hardware processor, wherein the programming instructions, when executed, cause the at least one hardware processor to perform operations comprising: determining a first NMR surface relaxation time of the rock sample having the saturation level based on an NMR relaxation time of oil and an NMR relaxation time of the rock sample having the saturation level at each of the plurality of temperatures; determining a first temperature sensitivity based on the first NMR surface relaxation time and a corresponding temperature; determining a second NMR surface relaxation time of the rock sample saturated with oil based on the NMR relaxation time of the oil and the NMR relaxation time of the rock sample saturated with oil at each of the plurality of temperatures; determining a second temperature sensitivity based on the second NMR surface relaxation time and a corresponding temperature; and determining the wettability of the rock sample based on the first temperature sensitivity and the second temperature sensitivity.

The foregoing and other embodiments may each optionally include, alone or in combination, one or more of the following features:

a first aspect combinable with a general implementation, wherein the wettability of the rock sample is determined according to the following formula:

wherein WI represents the wettability of the rock sample, m_{o_w}Represents the first temperature sensitivity, and m_oRepresenting the second temperature sensitivity.

Implementations of the subject matter and the functional operations described in this specification can be implemented in digital electronic circuitry, in tangibly embodied computer software or firmware, in computer hardware, including the structures disclosed in this specification and their structural equivalents, or in combinations of one or more of them. Embodiments of the subject matter described in this specification can be implemented as one or more computer programs, i.e., one or more modules of computer program instructions encoded on a tangible, non-transitory computer storage medium for execution by, or to control the operation of, data processing apparatus. Alternatively or additionally, the program instructions may be encoded on an artificially generated propagated signal (e.g., a machine-generated electrical, optical, or electromagnetic signal) that is generated to encode information for transmission to suitable receiver apparatus for execution by a data processing apparatus. The computer storage medium may be a machine-readable storage device, a machine-readable storage substrate, a random or serial access memory device, or a combination of one or more of them.

The terms "data processing apparatus," "computer," or "electronic computer apparatus" (or equivalents thereof as understood by those of ordinary skill in the art) refer to data processing hardware and include various devices, apparatus, and machines for processing data, including, for example, a programmable processor, a computer, or multiple processors or computers. The apparatus can also be or include special purpose logic circuitry, e.g., a Central Processing Unit (CPU), an FPGA (field programmable gate array), or an ASIC (application-specific integrated circuit). In some embodiments, the data processing apparatus or dedicated logic circuitry may be hardware-based or software-based. The apparatus can optionally include code that creates an execution environment for the computer program, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them. The present disclosure contemplates the use of data processing devices with or without conventional operating systems (e.g., LINUX, UNIX, WINDOWS, MAC OS, ANDROID, or IOS).

A computer program (also can be called or described as a program, software application, module, software module, script, or code) can be written in any form of programming language, including: a compiled or interpreted language, or a declarative or procedural language, and the computer program may be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. The computer program may, but need not, correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network. While the portions of the program shown in the various figures are illustrated as individual modules that implement the various features and functionality through various objects, methods, or other processes, the program may alternatively include multiple secondary modules, third party services, components, or libraries. Rather, the features and functionality of the various components may be combined into a single component, as appropriate.

The processes and logic flows described in this specification can be performed by one or more programmable computers executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., a CPU, FPGA or ASIC.

A computer suitable for execution of a computer program may be based on a general purpose or special purpose microprocessor, both or any other type of CPU. Generally, a CPU will receive instructions and data from a read-only memory (ROM) or a Random Access Memory (RAM) or both. The essential elements of a computer are a CPU for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto-optical disks, or optical disks. However, the computer need not have these devices. Further, the computer may be embedded in another device, e.g., a mobile telephone, a Personal Digital Assistant (PDA), a mobile audio or video player, a game player, a Global Positioning System (GPS) receiver, or a portable storage device (e.g., a Universal Serial Bus (USB) flash drive), to name a few.

Computer-readable media (transitory or non-transitory as appropriate) suitable for storing computer program instructions and data include all forms of non-volatile memory, media and memory devices, including by way of example semiconductor memory devices, such as erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), and flash memory devices; magnetic disks (e.g., internal hard disks or removable disks); magneto-optical disks; and CD-ROM, DVD +/-R, DVD-RAM and DVD-ROM disks. The memory may store various objects or data, including: caches, classes, frames, applications, backup data, jobs, web pages, web page templates, database tables, knowledge bases storing business information or dynamic information, and any other suitable information including any parameters, variables, algorithms, instructions, rules, constraints, references thereto. In addition, the memory may also include any other suitable data, such as logs, policies, security or access data or reporting files. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

To provide for interaction with a user, embodiments of the subject matter described in this specification can be implemented on a computer having a display device (e.g., a CRT (cathode ray tube), LCD (liquid crystal display), LED (light emitting diode), or plasma monitor) for displaying information to the user and a keyboard and a pointing device (e.g., a mouse, a trackball, or a trackpad) by which the user can provide input to the computer. Touch screens (e.g., a tablet computer surface with pressure sensitivity or a multi-touch screen using capacitive or electrical sensing) can also be used to provide input to the computer. Other types of devices may also be used to provide for interaction with a user; for example, feedback provided to the user can be any form of sensory feedback, e.g., visual feedback, auditory feedback, or tactile feedback; and input from the user may be received in any form, including acoustic, speech, or tactile input. In addition, the computer may interact with the user by sending documents to and receiving documents from the device used by the user; for example, a user is interacted with by sending a web page to a web browser on a user client device in response to a request received from the web browser.

The terms "graphical user interface" or "GUI" may be used in the singular or plural to describe one or more graphical user interfaces and each display of a particular graphical user interface. Thus, the GUI may represent any graphical user interface, including but not limited to a web browser, touch screen, or Command Line Interface (CLI) that processes information and efficiently presents the results of the information to the user. In general, the GUI may include a number of User Interface (UI) elements, some or all of which are associated with a web browser, such as interactive fields, drop-down lists, and buttons that are operable by a business suite user. These UI elements may relate to or represent functions of a web browser.

Implementations of the subject matter described in this specification can be implemented in a computing system that includes a back-end component (e.g., as a data server), or that includes a middleware component (e.g., an application server), or that includes a front-end component (e.g., a client computer having a graphical user interface or a web browser through which a user can interact with an implementation of the subject matter described in this specification), or any combination of one or more such back-end, middleware, or front-end components. The components of the system may be interconnected by any form or means of wired or wireless digital data communication (e.g., a communication network). Examples of communication networks include a Local Area Network (LAN), a Radio Access Network (RAN), a Metropolitan Area Network (MAN), a Wide Area Network (WAN), Worldwide Interoperability for Microwave Access (WIMAX), a Wireless Local Area Network (WLAN) using, for example, 802.11a/b/g/n and 802.20, all or a portion of the Internet. The network may communicate, for example, Internet Protocol (IP) packets, frame relay frames, Asynchronous Transfer Mode (ATM) cells, voice, video, data, or other suitable information between network addresses.

The computer system may include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other.

In some implementations, any or all of the components (hardware or software) of the computing system may interface with each other or with interfaces using an Application Programming Interface (API) or service layer. The API may include specifications for routines, data structures, and object classes. An API may be independent or dependent on the computer language and refers to a complete interface, a single function, or even a collection of APIs. The service layer provides software services to the computing system. The functionality of the various components of the computing system may be accessible to all service consumers via the service layer. The software service provides reusable, defined business functions through defined interfaces. For example, the interface may be software written in JAVA, C + +, or other suitable language that provides data in an extensible markup language (XML) format or other suitable format. The API or service layer may be an integrated component or a stand-alone component related to other components of the computing system. Moreover, any or all portions of the service layer may be implemented as sub-modules or sub-modules of another software module, enterprise application, or hardware module without departing from the scope of the present disclosure.

While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any disclosure or of what may be claimed, but rather as descriptions of features of particular implementations that may be specific to particular common content. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

Specific embodiments of the present subject matter have been described. Other implementations, modifications, and substitutions of the described implementations are apparent to those of skill in the art and are within the scope of the following claims. Although operations are depicted in the drawings or claims in a particular order, this should not be understood as: it may be desirable to perform the operations in the particular order shown, or in sequential order, or to perform all of the operations shown (some of which may be considered optional) in order to achieve desirable results. In some circumstances, multitasking and parallel processing may be advantageous.

Moreover, the separation or integration of various system modules and components in the embodiments described above should not be understood as requiring such separation or integration in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

Accordingly, the above description of example embodiments does not define or constrain this disclosure. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of this disclosure.