阅读说明：本技术 海上储层连通性评价方法及其在储量计算的应用 (Offshore reservoir connectivity evaluation method and application thereof in reserve calculation ) 是由 王显南 刘超 肖东 关利军 王勇 罗鹏 顾玉洋 于 2019-10-24 设计创作，主要内容包括：本发明公开了一种海上储层连通性评价方法及其在储量计算的应用,海上储层连通性评价方法包括以下步骤：S1、测井获得间隔相邻的第一储层和第二储层的位置、第一储层和第二储层之间的泥岩层的厚度以及物性特征；S2、将泵抽探针坐封所述第一储层中,将监听探针坐封所述第二储层中；S3、所述泵抽探针在所述第一储层中进行泵轴和压恢,所述监听探针在所述第二储层中探测所述第二储层的压力变化；S4、根据所述监听探针探测到所述第二储层的压力变化来判定所述第一储层和第二储层之间的连通性。本发明的海上储层连通性评价方法,在井况条件复杂的情况下,对海上浅层油藏垂向连通性评价提供快速可靠的依据,从而更好降低储量计算的不确定性。(The invention discloses an offshore reservoir connectivity evaluation method and application thereof in reserve calculation, wherein the offshore reservoir connectivity evaluation method comprises the following steps: s1, logging to obtain the positions of a first reservoir and a second reservoir which are adjacent to each other, the thickness of a mudstone layer between the first reservoir and the second reservoir and physical property characteristics; s2, setting the pumping probe in the first reservoir and setting the monitoring probe in the second reservoir; s3, the pumping probe performs pump shaft and pressure recovery in the first reservoir, and the monitoring probe detects pressure change of the second reservoir in the second reservoir; and S4, determining the connectivity between the first reservoir and the second reservoir according to the pressure change of the second reservoir detected by the monitoring probe. The offshore reservoir connectivity evaluation method provides a quick and reliable basis for the vertical connectivity evaluation of the offshore shallow reservoir under the condition of complex well conditions, so that the uncertainty of reserve calculation is better reduced.)

1. An offshore reservoir connectivity evaluation method is characterized by comprising the following steps:

s1, logging to obtain the positions of a first reservoir and a second reservoir which are adjacent to each other, the thickness of a mudstone layer between the first reservoir and the second reservoir and physical property characteristics;

s2, setting the pumping probe in the first reservoir and setting the monitoring probe in the second reservoir;

s3, the pumping probe performs pump shaft and pressure recovery in the first reservoir, and the monitoring probe detects pressure change of the second reservoir in the second reservoir;

and S4, determining the connectivity between the first reservoir and the second reservoir according to the pressure change of the second reservoir detected by the monitoring probe.

2. An offshore reservoir connectivity evaluation method according to claim 1, wherein in step S4, when the variation in pressure of the second reservoir detected by the sniffer probe is greater than 0.5psi, it is determined that the first reservoir and the second reservoir are in communication; otherwise, the communication is not connected.

3. An offshore reservoir connectivity evaluation method according to claim 1, wherein in step S4, when the variation in pressure of the second reservoir detected by the sniffer probe is greater than 0.5psi and the sniffer probe responds by spherical flow or radial flow, it is determined that the first reservoir and the second reservoir are in communication; otherwise, the communication is not connected.

4. An offshore reservoir connectivity evaluation method according to claim 1, wherein the pumping probe and the monitoring probe are both connected to a main pump;

in step S3, the pumping probe performs pumping in the first reservoir at a predetermined first flow rate and a predetermined second flow rate, and finally stops pumping and recovering, with a flow rate of zero;

in step S4, the listening probe detects pressure changes in the second reservoir.

5. An offshore reservoir connectivity evaluation method according to claim 1, wherein in step S1, the physical characteristics of the shale layer include porosity, permeability and neutron density.

6. An offshore reservoir connectivity evaluation method according to claim 1, wherein in step S2, a separation distance between the pumping probe and the listening probe is set according to a thickness of the mudstone layer.

7. Use of the offshore reservoir connectivity evaluation method of any one of claims 1 to 6 for reserve calculation.

8. Use of an offshore reservoir connectivity evaluation method in reserve calculation according to claim 7, wherein when a first reservoir and a second reservoir which are adjacent at an interval from top to bottom are communicated and an oil-water interface exists below the second reservoir, the reserves of the first reservoir and the second reservoir are calculated as the ascertained reserves.

9. The application of the offshore reservoir connectivity evaluation method in reserve calculation according to claim 1, wherein when a first reservoir and a second reservoir which are vertically spaced and adjacent are not communicated and an oil-water interface exists between the second reservoir and a water layer below the bottom of the second reservoir, the reserve calculation of the first reservoir comprises ascertaining the reserve, the first reservoir sand body is extrapolated to obtain the controlled reserve, and the reserve calculation of the second reservoir is the ascertained reserve.

10. Use of the offshore reservoir connectivity evaluation method of claim 1 in reserve calculation, wherein when a first reservoir and a second reservoir which are adjacent to each other at an upper-lower interval are not communicated and no oil-water interface exists below the second reservoir, the reserve calculation of the first reservoir and the second reservoir comprises ascertaining the reserve and controlling the reserve.

Technical Field

The invention relates to the field of offshore reservoir evaluation, in particular to an offshore reservoir connectivity evaluation method and application thereof in reserve calculation.

Background

Reservoir vertical connectivity refers to the ability to flow vertically between multiple reservoirs in a reservoir. Typically, when a reservoir has multiple reservoirs, pressure profiling is performed using pressure measurements from formation testing. If the connectivity among the reservoirs is good, the pressure of each reservoir is on a pressure gradient line, no pressure gradient difference exists, the technology is generally applied to domestic and foreign oil fields, and the key in the application of the technology is to obtain high-quality pressure pretest data and accurate pressure gradient.

The prior patent CN104285034A discloses an evaluation method of reservoir connectivity in a hydrocarbon reservoir, which is used for evaluating connectivity between multiple parts in the hydrocarbon reservoir, and the specific method is as follows: collecting a plurality of hydrocarbon samples at corresponding different depths within a hydrocarbon reservoir; determining a plurality of actual heavy fraction concentrations of hydrocarbons at respective different depths using fluorescence intensities based on the plurality of hydrocarbon samples; determining a plurality of estimated heavy ends concentrations for the hydrocarbons at respective different depths; and comparing the plurality of actual heavy fraction concentrations of hydrocarbons to a plurality of estimated heavy fraction concentrations of hydrocarbons to assess connectivity between the plurality of portions of the hydrocarbon reservoir. The patent is not applicable to offshore shallow heavy oil reservoirs, and a representative formation fluid is obtained firstly for users, and the asphalt content of heavy oil is less than 1%, so that the analysis method is applicable.

The two methods for evaluating the vertical connectivity explained above are influenced by underground and ground dual factors such as geological oil reservoirs, ocean environments and the like in the offshore oil field exploration and development environment, the faced problems are quite different from the land, especially in shallow oil reservoirs, the underground reservoir is very loose, irregular borehole diameter expansion and slurry filtrate invasion depth caused by slurry drilling cause great influence on the quality of data recorded in stratum testing, thereby bringing great uncertainty to pressure measurement and downhole fluid analysis, and having certain limitation.

Disclosure of Invention

The invention aims to solve the technical problem of providing an offshore reservoir connectivity evaluation method suitable for evaluating the vertical connectivity of a reservoir under the complex well and mine conditions and application of the offshore reservoir connectivity evaluation method in reserve calculation.

The technical scheme adopted by the invention for solving the technical problems is as follows: provided is an offshore reservoir connectivity evaluation method, which comprises the following steps:

s1, logging to obtain the positions of a first reservoir and a second reservoir which are adjacent to each other, the thickness of a mudstone layer between the first reservoir and the second reservoir and physical property characteristics;

s2, setting the pumping probe in the first reservoir and setting the monitoring probe in the second reservoir;

s3, the pumping probe performs pump shaft and pressure recovery in the first reservoir, and the monitoring probe detects pressure change of the second reservoir in the second reservoir;

and S4, determining the connectivity between the first reservoir and the second reservoir according to the pressure change of the second reservoir detected by the monitoring probe.

Preferably, in step S4, when the pressure change of the second reservoir detected by the monitor probe is greater than 0.5psi, it is determined that the first reservoir and the second reservoir are connected; otherwise, the communication is not connected.

Preferably, in step S4, when the variation in pressure of the second reservoir detected by the monitor probe is greater than 0.5psi and the monitor probe responds by spherical flow or radial flow, it is determined that the first reservoir and the second reservoir are in communication; otherwise, the communication is not connected.

Preferably, the pumping probe and the monitoring probe are both connected with a main pump;

in step S3, the pumping probe performs pumping in the first reservoir at a predetermined first flow rate and a predetermined second flow rate, and finally stops pumping and recovering, with a flow rate of zero;

in step S4, the listening probe detects pressure changes in the second reservoir.

Preferably, in step S1, the physical characteristics of the shale layer include porosity, permeability, and neutron density.

Preferably, in step S2, a separation distance between the pumping probe and the listening probe is set according to a thickness of the mudstone layer.

The invention also provides application of the offshore reservoir connectivity evaluation method in reserve calculation.

Preferably, when the first reservoir and the second reservoir which are adjacent at intervals up and down are communicated and an oil-water interface exists below the second reservoir, the reserves of the first reservoir and the second reservoir are calculated as the ascertained reserves.

Preferably, when the first reservoir and the second reservoir which are adjacent at the upper-lower interval are not communicated, and a water layer is arranged below the bottom of the second reservoir, and an oil-water interface exists between the second reservoir and the water layer, the reserve calculation of the first reservoir comprises the steps of ascertaining the reserve, extrapolating sand bodies of the first reservoir to obtain a control reserve, and calculating the reserve of the second reservoir as the ascertained reserve.

Preferably, when the first reservoir and the second reservoir which are adjacent at the upper and lower intervals are not communicated and an oil-water interface does not exist below the second reservoir, the reserve calculation of the first reservoir and the second reservoir comprises the exploration reserve and the control reserve.

According to the offshore reservoir connectivity evaluation method, the reservoir connectivity is evaluated by combining the logging information and the interference test method of stratum test, and under the condition of complex well conditions, a quick and reliable basis is provided for vertical connectivity evaluation of the offshore shallow oil reservoir, so that the uncertainty of reserve calculation is better reduced; when a shallow reservoir and an underground reservoir are very loose, the quality of data recorded in stratum testing can be guaranteed when a borehole is irregular and mud filtrate is deeply invaded, and pressure measurement and underground fluid analysis can be determined, so that the vertical connectivity of the reservoir can be well evaluated. During the exploration phase, a data basis can be provided for optimizing the reserve calculation scheme.

Drawings

The invention will be further described with reference to the accompanying drawings and examples, in which:

FIG. 1 is a flow chart of a method for offshore reservoir connectivity evaluation in accordance with an embodiment of the present invention;

fig. 2 is a schematic cross-sectional structure diagram of a reservoir in the offshore reservoir connectivity evaluation method according to an embodiment of the invention.

Detailed Description

For a more clear understanding of the technical features, objects and effects of the present invention, embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

With reference to fig. 1 and 2, the method for evaluating connectivity of an offshore reservoir according to an embodiment of the present invention includes the following steps:

and S1, logging to obtain the position of the first reservoir 10 and the second reservoir 20 which are adjacent to each other, the thickness of the mudstone layer 30 between the first reservoir 10 and the second reservoir 20 and the physical property characteristics.

The logging means includes conventional logging means such as gamma, resistivity, neutron density and porosity, and the positions of reservoirs, such as the first reservoir 10 and the second reservoir 20 which are adjacent to each other, are known through data obtained through logging, and the thickness, physical property characteristics and the like of a mudstone layer 30 between every two reservoirs are obtained. Physical properties of the mudstone layer 30 include porosity, permeability, and neutron density, among others.

The separation distance between the pumping probe 10 and the listening probe 20, which are subsequently probed, is determined by the obtained thickness of the mudstone layer 30.

S2, set the pumping probe 1 in the first reservoir 10, and set the listening probe 2 in the second reservoir 20.

Wherein, the probe 1 of pumping and monitor probe 2 and all connect the main pump, and the separation distance between probe 1 of pumping and monitor probe 2 sets up according to the thickness of argillite layer 30, optional 2-7 meters. For example, for a thickness of 4-5m for mudstone 30, the separation distance between pumping probe 1 and sniffer probe 2 is set to be greater than the thickness, for example, 5m or more.

As shown in fig. 2, in this embodiment, a first reservoir 10 is located above a second reservoir 20, a pumping probe 1 penetrates into the first reservoir 10 located above, and a monitor probe 2 penetrates into the second reservoir 20 located below. In an embodiment thereof, the first reservoir 10 may be located below the second reservoir 20, with the pumping probe 1 penetrating into the first reservoir 10 located below.

S3, pumping probe 1 to pump shaft and pressure recovery in the first reservoir 10, and listening probe 2 to detect pressure change in the second reservoir 20.

The pumping probe 1 performs pumping in the first reservoir at a first flow rate and a second flow rate which are preset, and finally stops pumping and recovering, wherein the flow rate is zero.

And S4, determining the connectivity between the first reservoir 10 and the second reservoir 20 according to the pressure change of the second reservoir 20 detected by the monitoring probe 2.

Wherein the monitor probe 2 detects pressure changes in the second reservoir 20.

When the pressure change of the second reservoir 20 detected by the monitoring probe 2 is greater than 0.5psi, the first reservoir 10 and the second reservoir 20 are judged to be communicated; otherwise, the communication is not connected. Or when the pressure change of the second reservoir 20 detected by the monitor probe 2 is greater than 0.5psi and the monitor probe 2 responds by spherical flow or radial flow, the first reservoir 10 and the second reservoir 20 are judged to be communicated; otherwise, the communication is not connected.

The offshore reservoir connectivity evaluation method can successfully confirm the connectivity of the reservoir, not only provides support for optimizing reserve calculation, but also provides data information for future development and design schemes from an early stage.

The offshore reservoir connectivity evaluation method is applied to reserve calculation, and reserve calculation is determined through evaluation of connectivity.

Referring to fig. 2, with the first reservoir 10 above and the second reservoir 20 below, connectivity of the two reservoirs is obtained by the connectivity evaluation method described above. Wherein:

when the first reservoir 10 and the second reservoir 20 which are adjacent at intervals up and down are communicated and an oil-water interface exists below the second reservoir 20, the reserves of the first reservoir 10 and the second reservoir 20 are calculated as the ascertained reserves.

When the first reservoir 10 and the second reservoir 20 which are adjacent at intervals up and down are not communicated, a water layer is arranged below the bottom of the second reservoir 20, and an oil-water interface exists between the second reservoir 20 and the water layer, the reserve calculation of the first reservoir 10 comprises the ascertained reserve, the sand body of the first reservoir 20 is extrapolated to obtain the controlled reserve, and the reserve of the second reservoir 20 is calculated as the ascertained reserve.

When the first reservoir 10 and the second reservoir 20 which are adjacent at intervals up and down are not communicated and an oil-water interface does not exist below the second reservoir 20, the reserve calculation of the first reservoir 10 and the second reservoir 20 comprises the exploration reserve and the control reserve.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.