阅读说明：本技术 流体性质识别方法及装置 (Fluid property identification method and device ) 是由 林学春 闫林辉 余茂生 黄国梁 牛伟丽 金海锋 王磊 曾海伟 刘文凤 于 2018-09-05 设计创作，主要内容包括：本发明公开了一种流体性质识别方法及装置,属于石油测井工程技术领域。通过获取目标储层中每一层位的测井参数,进而获取每一层位的束缚水饱和度,以及根据不同测井参数计算出的第一视地层水电阻率和第二视地层水电阻率,根据上述三个参数和预设判别标准,获取目标储层中每一层位的流体性质。上述方法简单高效,易于实施,识别结果准确率高,是识别低阻砂岩储层流体性质的有效方法。(The invention discloses a fluid property identification method and device, and belongs to the technical field of petroleum logging engineering. Acquiring the saturation of the bound water of each layer by acquiring the logging parameters of each layer in the target reservoir, calculating the first apparent formation water resistivity and the second apparent formation water resistivity according to different logging parameters, and acquiring the fluid property of each layer in the target reservoir according to the three parameters and a preset discrimination standard. The method is simple and efficient, is easy to implement, has high identification result accuracy, and is an effective method for identifying the properties of the low-resistance sandstone reservoir fluid.)

1. A fluid property identification method, the method comprising:

acquiring logging parameters of each layer in a target reservoir;

classifying the pore structure of each layer according to the logging parameters of each layer to obtain the pore structure type of each layer;

acquiring the irreducible water saturation of each layer according to the pore structure type of each layer, the irreducible water saturation calculation model of each type of pore structure and the logging parameters of each layer;

acquiring a first apparent formation water resistivity and a second apparent formation water resistivity of each layer according to the logging parameters of each layer, wherein the first apparent formation water resistivity and the second apparent formation water resistivity are apparent formation water resistivities calculated according to different logging parameters;

acquiring the fluid property of each layer according to the saturation of the bound water of each layer, the first apparent formation water resistivity, the second apparent formation water resistivity and a preset discrimination standard;

the preset discrimination criteria include:

when the horizon i is

when R of the horizon i_wa/R_{wa_sp}>4 and

when R of the horizon i_wa/R_{wa_sp}<4 and S_wi<At 52 time, or

the horizon i is a certain to-be-detected horizon in the target reservoir;

R_waa first apparent formation water resistivity for the horizon i in units of ohm-meters;

R_{wa_SP}a second apparent formation water resistivity for the horizon i in units of ohm-meters;

S_withe irreducible water saturation for the horizon i is 1%.

2. The method of claim 1, wherein the classifying the pore structure of each horizon according to the logging parameters of each horizon comprises:

when said horizon is

when said horizon is

when said horizon is

when said horizon is

wherein K is permeability with unit of 10^-3μm²；

Φ is the first porosity in 1%.

3. The method of claim 2, wherein the irreducible water saturation calculation model for each type of pore structure comprises:

when the pore structure of the horizon is of a first type or a second type, the expression of the irreducible water saturation calculation model is as follows:

S_wi＝＝0.0622*(Φ_D-Φ_N)²-1.3429*(Φ_D-Φ_N)+30.245；

when the pore structure of the horizon is of the third type or the fourth type, the expression of the irreducible water saturation calculation model is as follows:

S_wi＝-10.732*log₁₀(K/Φ)+32.78；

wherein phi_DIs a second porosity calculated from density in units of 1%;

Φ_Nis the third porosity calculated from neutrons, in units of 1%;

k is the permeability in 10^-3μm²；

Φ is the first porosity in 1%.

4. The method of claim 1, wherein the obtaining a first apparent formation water resistivity for each horizon from the logging parameters for each horizon comprises:

and acquiring the first apparent formation water resistivity of each layer according to the resistivity, the first porosity, the cementation index and the lithology coefficient of each layer.

5. The method of claim 1, wherein the obtaining a second apparent formation water resistivity for each horizon from the logging parameters for each horizon comprises:

and acquiring the second apparent formation water resistivity of each layer according to the mud filtrate resistivity, the natural potential amplitude and the natural potential coefficient of each layer.

6. The method of claim 1, further comprising:

acquiring the irreducible water saturation, the first apparent formation water resistivity and the second apparent formation water resistivity of the layer with known actual fluid properties;

acquiring the fluid property of the horizon according to the saturation of the bound water of the horizon, the first apparent formation water resistivity, the second apparent formation water resistivity and a preset discrimination standard;

and verifying whether the fluid property acquired by adopting the preset judgment standard is consistent with the actual fluid property.

7. The method of any of claims 1-6, wherein the logging parameters comprise: resistivity curve, sonic time difference curve, compensated neutron curve, compensated density curve, natural gamma curve, well diameter curve, and natural potential curve.

8. A fluid property identification device, the device comprising:

the parameter acquisition module is used for acquiring logging parameters of each horizon in a target reservoir;

the classification module is used for classifying the pore structure of each layer according to the logging parameters of each layer to obtain the pore structure type of each layer;

the irreducible water saturation obtaining module is used for obtaining the irreducible water saturation of each layer according to the pore structure type of each layer, the irreducible water saturation calculation model of each type of pore structure and the logging parameters of each layer;

the apparent formation water resistivity acquisition module is used for acquiring a first apparent formation water resistivity and a second apparent formation water resistivity of each layer according to the logging parameters of each layer, wherein the first apparent formation water resistivity and the second apparent formation water resistivity are apparent formation water resistivities calculated according to different logging parameters;

the fluid property acquisition module is used for acquiring the fluid property of each layer according to the saturation of the bound water of each layer, the first apparent formation water resistivity, the second apparent formation water resistivity and a preset discrimination standard;

the preset discrimination criteria include:

when the horizon i is

when R of the horizon i_wa/R_{wa_sp}>4 anddetermining the layer i to be an oil-water layer;

when R of the horizon i_wa/R_{wa_sp}<4 and S_wi<At 52 time, orDetermining the layer position i as a water layer;

the horizon i is a certain to-be-detected horizon in a target reservoir;

R_wais the first apparent formation water resistivity in ohm-meters;

R_{wa_SP}the second apparent formation water resistivity in ohm-meters;

S_withe irreducible water saturation of the horizon is 1%.

9. The apparatus of claim 8, wherein the classification module is configured to:

when said horizon is

when said horizon isThen, determining the pore structure of the layer as a second type;

when said horizon isDetermining the pore structure of the layer as a third type;

when said horizon isDetermining the pore structure of the layer as a fourth type;

wherein K is permeability with unit of 10^-3μm²；

Φ is the first porosity in 1%.

10. The apparatus of claim 9, wherein the irreducible water saturation calculation model for each type of pore structure comprises:

when the pore structure of the horizon is of a first type or a second type, the expression of the irreducible water saturation calculation model is as follows:

S_wi＝＝0.0622*(Φ_D-Φ_N)²-1.3429*(Φ_D-Φ_N)+30.245；

when the pore structure of the horizon is of the third type or the fourth type, the expression of the irreducible water saturation calculation model is as follows:

S_wi＝-10.732*log₁₀(K/Φ)+32.78；

wherein phi_DIs a second porosity calculated from density in units of 1%;

Φ_Nis the third porosity calculated from neutrons, in units of 1%;

k is the permeability in 10^-3μm²；

Φ is the first porosity in 1%.

Technical Field

The invention relates to the technical field of petroleum logging engineering, in particular to a fluid property identification method and device.

Background

With the continuous expansion of the field of oil-gas exploration and development in China, research objects are gradually shifted from original simple high-amplitude structural oil-gas reservoirs to complex oil-gas reservoirs with low porosity, low resistivity, complex lithology and the like. The logging interpretation is carried out on the low-permeability and low-resistance sandstone reservoir under the condition of salt-water slurry, and the technical problem of fluid property identification needs to be overcome so as to meet the requirement of later-stage oil reservoir exploration and development.

In the aspect of fluid identification, a great deal of research has been done by the predecessors, including a conventional intersection graph method, a PICKETT method, a Fisher discriminant analysis method, a gray cluster identification method and the like, and due to the particularity of geological conditions, the identification methods are not targeted, and particularly the identification accuracy rate of the fluid properties of the low-resistance sandstone reservoir is low.

Disclosure of Invention

The embodiment of the invention provides a fluid property identification method and device, which can solve the problem that the existing identification method has low accuracy in identifying the fluid property of a low-resistance sandstone reservoir. The technical scheme is as follows:

in one aspect, a fluid property identification method is provided, the method comprising:

acquiring logging parameters of each layer in a target reservoir;

classifying the pore structure of each layer according to the logging parameters of each layer to obtain the pore structure type of each layer;

acquiring the saturation of the irreducible water of each layer according to the type of the pore structure of each layer, the irreducible water saturation calculation model of each type of pore structure and the logging parameters of each layer;

acquiring a first apparent formation water resistivity and a second apparent formation water resistivity of each layer according to the logging parameters of each layer, wherein the first apparent formation water resistivity and the second apparent formation water resistivity are apparent formation water resistivities calculated according to different logging parameters;

acquiring the fluid property of each layer according to the saturation of the bound water of each layer, the first apparent formation water resistivity, the second apparent formation water resistivity and a preset discrimination standard;

the preset discrimination criteria include:

when the horizon i is

Determining the layer position i as an oil layer and a poor oil layer;

when R of the horizon i_wa/R_{wa_sp}>4 and

determining the layer i as an oil-water layer;

when R of the horizon i_wa/R_{wa_sp}<4 and S_wi<At 52 time, or

Determining the layer i as a water layer;

the horizon i is a certain to-be-detected horizon in a target reservoir;

R_wathe resistivity of the first apparent formation water of the horizon i is in ohm meters;

R_{wa_SP}the second apparent formation water resistivity of the horizon i is in ohm meters;

S_withe irreducible water saturation for this horizon i is given in units of 1%.

In one possible implementation, the classifying the pore structure of each horizon according to the logging parameters of each horizon includes:

when the horizon isThen determining the pore structure of the layer as a first type;

when the horizon is

Then, determining the pore structure of the layer as a second type;

when the horizon is

Then, determining the pore structure of the layer as a third type;

when the horizon is

Determining the pore structure of the layer as a fourth type;

wherein K is permeability with unit of 10^-3μm²；

Φ is the first porosity in 1%.

In one possible implementation, the irreducible water saturation calculation model for each type of pore structure includes:

when the pore structure of the horizon is of the first type or the second type, the expression of the irreducible water saturation calculation model is as follows:

S_wi＝＝0.0622*(Φ_D-Φ_N)²-1.3429*(Φ_D-Φ_N)+30.245；

when the pore structure of the horizon is of the third type or the fourth type, the expression of the irreducible water saturation calculation model is as follows:

S_wi＝-10.732*log₁₀(K/Φ)+32.78；

wherein phi_DIs a second porosity calculated from density in units of 1%;

Φ_Nis the third porosity calculated from neutrons, in units of 1%;

k is the permeability in 10^-3μm²；

Φ is the first porosity in 1%.

In one possible implementation, the obtaining a first apparent formation water resistivity of each horizon according to the logging parameters of each horizon includes:

and acquiring the first apparent formation water resistivity of each layer according to the resistivity, the first porosity, the cementation index and the lithology coefficient of each layer.

In one possible implementation, the obtaining a second apparent formation water resistivity of each horizon according to the logging parameters of each horizon includes:

and obtaining the second apparent formation water resistivity of each layer according to the mud filtrate resistivity, the natural potential amplitude and the natural potential coefficient of each layer.

In one possible implementation, the method further comprises:

acquiring the irreducible water saturation, the first apparent formation water resistivity and the second apparent formation water resistivity of the layer with known actual fluid properties;

acquiring the fluid property of the layer according to the saturation of the bound water of the layer, the first apparent formation water resistivity, the second apparent formation water resistivity and a preset discrimination standard;

and verifying whether the fluid property acquired by adopting the preset judgment standard is consistent with the actual fluid property.

In one possible implementation, the logging parameters include: resistivity curve, sonic time difference curve, compensated neutron curve, compensated density curve, natural gamma curve, well diameter curve, and natural potential curve.

In one aspect, there is provided a fluid property identification device, the device comprising:

the parameter acquisition module is used for acquiring logging parameters of each horizon in a target reservoir;

the classification module is used for classifying the pore structure of each layer according to the logging parameters of each layer to obtain the pore structure type of each layer;

the irreducible water saturation obtaining module is used for obtaining the irreducible water saturation of each layer according to the pore structure type of each layer, the irreducible water saturation calculation model of each type of pore structure and the logging parameters of each layer;

the system comprises a visual formation water resistivity acquisition module, a data acquisition module and a data processing module, wherein the visual formation water resistivity acquisition module is used for acquiring a first visual formation water resistivity and a second visual formation water resistivity of each layer according to logging parameters of each layer, and the first visual formation water resistivity and the second visual formation water resistivity are the visual formation water resistivities calculated according to different logging parameters;

the fluid property acquisition module is used for acquiring the fluid property of each layer according to the saturation of the bound water of each layer, the first apparent formation water resistivity, the second apparent formation water resistivity and a preset discrimination standard;

the preset discrimination criteria include:

when the horizon i is

Determining the layer position i as an oil layer and a poor oil layer;

when R of the horizon i_wa/R_{wa_sp}>4 and

determining the layer i as an oil-water layer;

when R of the horizon i_wa/R_{wa_sp}<4 and S_wi<At 52 time, or

Determining the layer i as a water layer;

the horizon i is a certain to-be-detected horizon in a target reservoir;

R_wathe resistivity of the first apparent formation water of the horizon i is in ohm meters;

R_{wa_SP}the second apparent formation water resistivity of the horizon i is in ohm meters;

S_withe irreducible water saturation for this horizon i is given in units of 1%.

In one possible implementation, the classification module is configured to:

when the horizon is

Then determining the pore structure of the layer as a first type;

when the horizon isThen, determining the pore structure of the layer as a second type;

when the horizon is

Then, determining the pore structure of the layer as a third type;

when the horizon is

Determining the pore structure of the layer as a fourth type;

wherein K is permeability with unit of 10^-3μm²；

Φ is the first porosity in 1%.

In one possible implementation, the irreducible water saturation calculation model for each type of pore structure includes:

when the pore structure of the horizon is of the first type or the second type, the expression of the irreducible water saturation calculation model is as follows:

S_wi＝＝0.0622*(Φ_D-Φ_N)²-1.3429*(Φ_D-Φ_N)+30.245；

when the pore structure of the horizon is of the third type or the fourth type, the expression of the irreducible water saturation calculation model is as follows:

S_wi＝-10.732*log₁₀(K/Φ)+32.78；

wherein phi_DIs a second porosity calculated from density in units of 1%;

Φ_Nis the third porosity calculated from neutrons, in units of 1%;

k is the permeability in 10^-3μm²；

Φ is the first porosity in 1%.

The technical scheme provided by the embodiment of the invention has the following beneficial effects:

acquiring the saturation of the bound water of each layer by acquiring the logging parameters of each layer in the target reservoir, calculating the first apparent formation water resistivity and the second apparent formation water resistivity according to different logging parameters, and acquiring the fluid property of each layer in the target reservoir according to the three parameters and a preset discrimination standard. The method is simple and efficient, is easy to implement, has high identification result accuracy, and is an effective method for identifying the properties of the low-resistance sandstone reservoir fluid.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a flow chart of a fluid property identification method provided by an embodiment of the present invention;

FIG. 2 is a flow chart of a fluid property identification method provided by an embodiment of the present invention;

FIG. 3 is a cross plot of a ratio of a first apparent formation water resistivity to a second apparent formation water resistivity and irreducible water saturation for an exemplary reservoir of interest provided by embodiments of the present invention;

FIG. 4 is a schematic diagram of a fluid property identification device according to an embodiment of the present invention;

fig. 5 is a schematic structural diagram of a computer device according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Fig. 1 is a flow chart of a fluid property identification method according to an embodiment of the present invention. Referring to fig. 1, the method includes:

101. and obtaining logging parameters of each horizon in the target reservoir.

102. And classifying the pore structure of each layer according to the logging parameters of each layer to obtain the pore structure type of each layer.

103. And acquiring the saturation of the irreducible water of each layer according to the type of the pore structure of each layer, the irreducible water saturation calculation model of each type of pore structure and the logging parameters of each layer.

104. And acquiring a first apparent formation water resistivity and a second apparent formation water resistivity of each layer according to the logging parameters of each layer, wherein the first apparent formation water resistivity and the second apparent formation water resistivity are the apparent formation water resistivities calculated according to different logging parameters.

105. And acquiring the fluid property of each layer according to the saturation of the bound water of each layer, the first apparent formation water resistivity, the second apparent formation water resistivity and a preset discrimination standard.

The preset discrimination criteria include:

when the horizon i is

Determining the layer position i as an oil layer and a poor oil layer;

when R of the horizon i_wa/R_{wa_sp}>4 anddetermining the layer i as an oil-water layer;

when R of the horizon i_wa/R_{wa_sp}<4 and S_wi<At 52 time, orThen the horizon i is determined to be the water layer.

The horizon i is a certain to-be-detected horizon in a target reservoir; r_waThe resistivity of the first apparent formation water of the horizon i is in ohm meters; r_{wa_SP}The second apparent formation water resistivity of the horizon i is in ohm meters; s_wiThe irreducible water saturation for this horizon i is given in units of 1%.

According to the method provided by the embodiment of the invention, the logging parameters of each layer in the target reservoir are obtained, so that the saturation of the irreducible water of each layer is obtained, the first apparent formation water resistivity and the second apparent formation water resistivity are calculated according to different logging parameters, and the fluid property of each layer in the target reservoir is obtained according to the three parameters and the preset discrimination standard. The method is simple and efficient, is easy to implement, has high identification result accuracy, and is an effective method for identifying the properties of the low-resistance sandstone reservoir fluid.

In one possible implementation, the classifying the pore structure of each horizon according to the logging parameters of each horizon includes:

when the horizon is

Then determining the pore structure of the layer as a first type;

when the horizon isThen, determining the pore structure of the layer as a second type;

when the horizon is

Then, determining the pore structure of the layer as a third type;

when the horizon isDetermining the pore structure of the layer as a fourth type;

wherein K is permeability with unit of 10^-3μm²(ii) a Φ is the first porosity in 1%.

In one possible implementation, the irreducible water saturation calculation model for each type of pore structure includes:

when the pore structure of the horizon is of the first type or the second type, the expression of the irreducible water saturation calculation model is as follows:

S_wi＝＝0.0622*(Φ_D-Φ_N)²-1.3429*(Φ_D-Φ_N)+30.245；

when the pore structure of the horizon is of the third type or the fourth type, the expression of the irreducible water saturation calculation model is as follows:

S_wi＝-10.732*log₁₀(K/Φ)+32.78；

wherein phi_DIs a second porosity calculated from density in units of 1%; phi_NIs the third porosity calculated from neutrons, in units of 1%; k is the permeability in 10^-3μm²(ii) a Φ is the first porosity in 1%.

In one possible implementation, the obtaining a first apparent formation water resistivity of each horizon according to the logging parameters of each horizon includes:

and acquiring the first apparent formation water resistivity of each layer according to the resistivity, the first porosity, the cementation index and the lithology coefficient of each layer.

In one possible implementation, the obtaining a second apparent formation water resistivity of each horizon according to the logging parameters of each horizon includes:

and obtaining the second apparent formation water resistivity of each layer according to the mud filtrate resistivity, the natural potential amplitude and the natural potential coefficient of each layer.

In one possible implementation, the method further comprises:

and acquiring the irreducible water saturation, the first apparent formation water resistivity and the second apparent formation water resistivity of the horizon with known actual fluid properties.

And acquiring the fluid property of the layer according to the saturation of the bound water of the layer, the first apparent formation water resistivity, the second apparent formation water resistivity and a preset discrimination standard.

And verifying whether the fluid property acquired by adopting the preset judgment standard is consistent with the actual fluid property.

In one possible implementation, the logging parameters include: resistivity curve, sonic time difference curve, compensated neutron curve, compensated density curve, natural gamma curve, well diameter curve, and natural potential curve.

All the above optional technical solutions may be combined arbitrarily to form the optional embodiments of the present disclosure, and are not described herein again.

Fig. 2 is a flow chart of a fluid property identification method according to an embodiment of the present invention. Referring to fig. 2, the embodiment may be applied to a computer device, and specifically, the embodiment includes:

201. and acquiring logging parameters of each layer in a target reservoir, wherein the target reservoir is a low-resistivity sandstone reservoir.

In the embodiment of the invention, whether the reservoir to be detected is a low-resistivity sandstone reservoir can be judged by the following method: in the same oil-water system, obtaining the resistivity of a hydrocarbon reservoir and the resistivity of a pure water layer, and determining that the hydrocarbon reservoir is a low-resistance sandstone reservoir when the ratio of the resistivity of the hydrocarbon reservoir to the resistivity of the pure water layer is less than 2; or taking the regional empirical standard of the resistivity of the hydrocarbon reservoir as a preset threshold, and determining that the hydrocarbon reservoir is a low-resistivity sandstone reservoir when the resistivity of the hydrocarbon reservoir is lower than the preset threshold. The determination process may be performed in other manners, which is not limited in this embodiment.

The logging parameters are obtained by logging in a conventional logging mode. The logging parameters can provide data support for subsequent calculation processes.

In one possible implementation, the logging parameters include: resistivity curve, sonic time difference curve, compensated neutron curve, compensated density curve, natural gamma curve, well diameter curve, and natural potential curve.

The resistivity curve, the acoustic time difference curve, the compensated neutron curve, the compensated density curve, the natural gamma curve, the well diameter curve and the natural potential curve are two-dimensional curves of logging parameters and depths obtained by logging according to corresponding methods respectively. Wherein the resistivity can reflect the resistivity of each depth medium in the well; the acoustic time difference can reflect the elasticity and density of formation rock, the properties of fluid in pores and the like; the compensated neutrons can reflect the percentage of the volume of fluid in the formation; offset density refers to the density per unit volume of solids and fluids in the formation; the natural gamma ray can reflect the clay content in the stratum and is an important parameter for judging the lithology of the stratum; the hole diameter is the size of a borehole and can reflect the working state of the well.

202. And classifying the pore structure of each layer according to the logging parameters of each layer to obtain the pore structure type of each layer.

The pore system of the rock is composed of two parts, namely a pore and a throat, wherein the pore is an expansion part in the system, and the throat is a fine part communicated with the pore. The structural characteristics of the rock pore system are usually expressed by pore structure, which refers to the type, size, distribution and interconnection of pores and throats within the rock. Since the irreducible water saturation calculation methods corresponding to different pore structure types may be inconsistent, in order to obtain accurate data of irreducible water saturation of each level, it is necessary to classify the pore structure of each level.

In one possible implementation, classifying the pore structure of each horizon according to the first porosity and permeability data in the logging parameters of each horizon comprises:

when the horizon is

Then determining the pore structure of the layer as a first type;

when the horizon isThen, determining the pore structure of the layer as a second type;

when the horizon is

Then, determining the pore structure of the layer as a third type;

when the horizon is

Determining the pore structure of the layer as a fourth type;

wherein K is the permeability, singlyBit is 10^-3μm²(ii) a Φ is the first porosity in 1%.

The capillary pressure curve displacement pressure of the first-class pore structure is the minimum, the maximum pore throat radius and throat radius are the maximum, and the physical property is the best; and the capillary pressure curve displacement pressure of the fourth type pore structure is the maximum, the maximum pore throat radius and the throat radius are the minimum, and the physical property is the worst.

Porosity refers to the ratio of the pore volume of rock to the total volume of rock, and reflects the ability of the formation to store fluids. When the well condition is good, the first porosity is neutron density porosity, and the first porosity is calculated according to the second porosity and the third porosity; when the diameter expansion is serious, namely the well diameter is large, the first porosity is acoustic porosity. The first porosity is calculated as follows:

ρ_b＝Φ·ρ_mf+(1-Φ-V_sh)·ρ_ma+V_sh·ρ_sh(1)

Φ_N＝Φ·Φ_Nmf+(1-Φ-V_sh)·Φ_Nma+V_sh·Φ_Nsh(2)

Δt＝Φ·Δt_mf+(1-Φ-V_sh)·Δt_ma+V_sh·Δt_sh(3)

in the formula, ρ_b、Φ_NAnd delta t is logging density, neutron and acoustic time difference respectively; rho_ma、Φ_Nma、Δt_maThe frame density, the neutron and the acoustic wave time difference are respectively; rho_sh、Φ_Nsh、Δt_shThe density, neutron and sound wave time difference of the argillaceous skeleton are respectively; phi is porosity; v_shIs the argillaceous content.

And (3) substituting the acquired parameters into formulas (1) and (2) to obtain the porosity phi, which is the neutron density porosity.

And (4) substituting the acquired parameters into a formula (3) to obtain the porosity phi, which is the acoustic porosity.

203. And acquiring the saturation of the irreducible water of each layer according to the type of the pore structure of each layer, the irreducible water saturation calculation model of each type of pore structure and the logging parameters of each layer.

In the process of transporting oil gas from an oil-producing layer to a sandstone reservoir, due to the wettability difference of oil, water and gas to rock and the action of capillary force, the transported oil gas cannot completely displace water in rock pores, and a certain amount of water remains in the rock pores. This portion of water is almost stagnant and is therefore referred to as irreducible water, and the corresponding saturation is referred to as irreducible water saturation. The calculation of irreducible water saturation is also different due to the different types of pore structures. In one possible implementation, the irreducible water saturation calculation model for each type of pore structure includes:

when the pore structure of the horizon is of the first type or the second type, the expression of the irreducible water saturation calculation model is as follows:

S_wi＝＝0.0622*(Φ_D-Φ_N)²-1.3429*(Φ_D-Φ_N)+30.245；

when the pore structure of the horizon is of the third type or the fourth type, the expression of the irreducible water saturation calculation model is as follows:

S_wi＝-10.732*log₁₀(K/Φ)+32.78；

wherein phi_DIs a second porosity calculated from density in units of 1%; phi_NIs the third porosity calculated from neutrons, in units of 1%; k is the permeability in 10^-3μm²(ii) a Φ is the first porosity in 1%.

204. And acquiring the first apparent formation water resistivity of each layer according to the logging parameters of each layer.

The formation water resistivity refers to the resistivity of water contained in reservoir rock and is an important parameter for well logging interpretation. The first apparent formation water resistivity is the formation water resistivity calculated from the resistivity and porosity. In one possible implementation, a first apparent formation water resistivity of each layer is obtained according to the resistivity, the first porosity, the cementation index and the lithology coefficient of each layer. Wherein, the calculation formula of the first apparent formation water resistivity is as follows:

in the formula, R_waThe first apparent formation water resistivity, calculated from resistivity and porosity, is in ohm-meters;

R_tis the formation resistivity in ohm-meters; Φ is the first porosity in 1%; m is a cementation index; a is the lithology index.

205. And acquiring the second apparent formation water resistivity of each layer according to the logging parameters of each layer. Wherein the second apparent formation water resistivity is a formation water resistivity calculated from the natural potential. In one possible implementation, the second apparent formation water resistivity of each layer is obtained according to the mud filtrate resistivity, the natural potential amplitude and the natural potential coefficient of each layer. Wherein, the calculation formula of the second apparent formation water resistivity is as follows:

in the formula, R_{wa_SP}The apparent formation water resistivity is calculated through natural potential, and the unit is ohm meter; r_mfTMud filtrate resistivity at formation temperature in ohm-meters; SSP is the natural potential amplitude value of the target layer section, and the unit is millivolt; k is the natural potential coefficient.

It should be noted that the first apparent formation water resistivity and the second apparent formation water resistivity may reflect changes in the properties of the fluid in the reservoir from different aspects.

206. And acquiring the fluid property of each layer according to the saturation of the bound water of each layer, the first apparent formation water resistivity, the second apparent formation water resistivity and a preset discrimination standard. The preset discrimination standard is the discrimination standard of the reservoir fluid property which is fitted through mathematical calculation according to the logging parameters and logging experience of the horizon of the actual known fluid property. Wherein, the preset discrimination criteria include:

when the horizon i is

Determining the layer position i as an oil layer and a poor oil layer;

when R of the horizon i_wa/R_{wa_sp}>4 and

determining the layer i as an oil-water layer;

when R of the horizon i_wa/R_{wa_sp}<4 and S_wi<At 52 time, or

Then the horizon i is determined to be the water layer.

The horizon i is a certain to-be-detected horizon in a target reservoir; r_waIs the first apparent formation water resistivity in ohm-meters; r_{wa_SP}The second apparent formation water resistivity in ohm-meters; s_wiThe irreducible water saturation for this horizon is given in units of 1%.

Furthermore, the identification result of the fluid property obtained by adopting the preset judgment standard can be verified, so that the accuracy of obtaining the fluid property through the preset judgment standard can be analyzed. The verification process may be: acquiring the irreducible water saturation, the first apparent formation water resistivity and the second apparent formation water resistivity of the layer with known actual fluid properties; acquiring the fluid property of the layer according to the saturation of the bound water of the layer, the first apparent formation water resistivity, the second apparent formation water resistivity and a preset discrimination standard; and verifying whether the fluid property acquired by adopting the preset judgment standard is consistent with the actual fluid property. For the reservoir stratum used for the verification process, when the fluid property obtained by adopting the preset judgment standard is consistent with the actual fluid property, the preset judgment standard is shown to be capable of accurately identifying the fluid property of the to-be-detected stratum; otherwise, the preset judgment standard is represented to be incapable of accurately identifying the fluid property of the layer to be detected. For all the horizons used for the verification process, the ratio of the number of the horizons which can be accurately identified by the preset discrimination standard to the total number of the horizons is the coincidence rate of identifying the fluid property by adopting the preset discrimination standard, and when the coincidence rate is higher, the accuracy of acquiring the fluid property by the preset discrimination standard is proved to be higher; when the coincidence rate is low, the accuracy rate of acquiring the fluid property by the preset judgment standard is proved to be low, and the preset judgment standard can be corrected to improve the identification accuracy rate.

Specifically, referring to fig. 3, fig. 3 is a cross plot of a ratio of a first apparent formation water resistivity and a second apparent formation water resistivity and an irreducible water saturation of an exemplary target reservoir provided by an embodiment of the present invention, where fig. 3 is a two-dimensional graph obtained by obtaining the first apparent formation water resistivity, the second apparent formation water resistivity and the irreducible water saturation of a horizon with known actual fluid properties, and taking the ratio of the first apparent formation water resistivity and the second apparent formation water resistivity as an abscissa and the irreducible water saturation data as an ordinate. From the analysis it can be derived: the coincidence rate between the actual fluid properties of all the layers and the fluid properties obtained by adopting the preset discrimination standard is 92%, namely the accuracy rate of obtaining the fluid properties by adopting the method provided by the embodiment of the invention is 92%, and the accuracy rate of identifying by adopting other commonly used identification methods at present is 81%.

According to the method provided by the embodiment of the invention, the logging parameters of each layer in the target reservoir are obtained, so that the saturation of the irreducible water of each layer is obtained, the first apparent formation water resistivity and the second apparent formation water resistivity are calculated according to different logging parameters, and the fluid property of each layer in the target reservoir is obtained according to the three parameters and the preset discrimination standard. The method is simple and efficient, is easy to implement, has high identification result accuracy, and is an effective method for identifying the properties of the low-resistance sandstone reservoir fluid. Furthermore, the accuracy of identifying the fluid property by adopting the fluid property identification method provided by the embodiment of the invention is higher, and the method is suitable for popularization and application.

Fig. 4 is a schematic structural diagram of a fluid property identification device provided in an embodiment of the present invention, and referring to fig. 4, the device includes:

and the parameter obtaining module 401 is configured to obtain a logging parameter of each horizon in the target reservoir.

And a classification module 402, configured to classify the pore structure of each layer according to the logging parameter of each layer, so as to obtain a pore structure type of each layer.

And an irreducible water saturation obtaining module 403, configured to obtain irreducible water saturation of each layer according to the type of the pore structure of each layer, the irreducible water saturation calculation model of each type of pore structure, and the logging parameter of each layer.

The apparent formation water resistivity obtaining module 404 is configured to obtain a first apparent formation water resistivity and a second apparent formation water resistivity of each layer according to the logging parameter of each layer, where the first apparent formation water resistivity and the second apparent formation water resistivity are apparent formation water resistivities calculated according to different logging parameters.

A fluid property obtaining module 405, configured to obtain a fluid property of each layer according to the saturation of the irreducible water of each layer, the first apparent formation water resistivity, the second apparent formation water resistivity, and a preset criterion.

The preset discrimination criteria include:

when the horizon i is

Determining the layer position i as an oil layer and a poor oil layer;

when R of the horizon i_wa/R_{wa_sp}>4 and

determining the layer i as an oil-water layer;

when R of the horizon i_wa/R_{wa_sp}<4 and S_wi<At 52 time, or

Determining the layer i as a water layer;

the horizon i is a certain to-be-detected horizon in a target reservoir; r_waIs the first apparent formation water resistivity in ohm-meters; r_{wa_SP}Is a secondDepending on the formation water resistivity, the unit is ohm meters; s_wiThe irreducible water saturation for this horizon is given in units of 1%.

In one possible implementation, the classification module 402 is configured to:

when the horizon is

Then determining the pore structure of the layer as a first type;

when the horizon is

Then, determining the pore structure of the layer as a second type;

when the horizon isThen, determining the pore structure of the layer as a third type;

when the horizon is

Determining the pore structure of the layer as a fourth type;

wherein K is permeability with unit of 10^-3μm²(ii) a Φ is the first porosity in 1%.

In one possible implementation, the irreducible water saturation calculation model for each type of pore structure includes:

when the pore structure of the horizon is of the first type or the second type, the expression of the irreducible water saturation calculation model is as follows:

S_wi＝＝0.0622*(Φ_D-Φ_N)²-1.3429*(Φ_D-Φ_N)+30.245；

when the pore structure of the horizon is of the third type or the fourth type, the expression of the irreducible water saturation calculation model is as follows:

S_wi＝-10.732*log₁₀(K/Φ)+32.78；

wherein phi_DIs the second pore calculated according to densityDegree, in units of 1%; phi_NIs the third porosity calculated from neutrons, in units of 1%; k is the permeability in 10^-3μm²(ii) a Φ is the first porosity in 1%.

It should be noted that: in the fluid property identification device provided in the above embodiment, only the division of the above functional modules is exemplified when identifying the fluid property, and in practical applications, the above functions may be distributed by different functional modules according to needs, that is, the internal structure of the apparatus may be divided into different functional modules to complete all or part of the above described functions. In addition, the fluid property identification device provided by the above embodiment and the fluid property identification method embodiment belong to the same concept, and the specific implementation process thereof is described in the method embodiment and is not described herein again.

According to the device provided by the embodiment of the invention, the logging parameters of each layer in the target reservoir are obtained, so that the saturation of the irreducible water of each layer is further obtained, the first apparent formation water resistivity and the second apparent formation water resistivity are calculated according to different logging parameters, and the fluid property of each layer in the target reservoir is obtained according to the three parameters and the preset discrimination standard. The method is simple and efficient, is easy to implement, has high identification result accuracy, and is an effective method for identifying the properties of the low-resistance sandstone reservoir fluid.

Fig. 5 is a schematic structural diagram of a computer device 500 according to an embodiment of the present invention, where the computer device 500 may generate a relatively large difference due to different configurations or performances, and may include one or more processors (CPUs) 501 and one or more memories 502, where the memory 502 stores at least one instruction, and the at least one instruction is loaded and executed by the processors 501 to implement the methods provided by the above method embodiments. Certainly, the computer device may further have components such as a wired or wireless network interface, a keyboard, and an input/output interface, so as to perform input and output, and the computer device may further include other components for implementing the functions of the device, which is not described herein again.

In an exemplary embodiment, a computer-readable storage medium, such as a memory, is also provided that includes instructions executable by a processor in a terminal to perform the fluid property identification method of the above embodiments. For example, the computer readable storage medium may be a ROM, a Random Access Memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like.

It will be understood by those skilled in the art that all or part of the steps for implementing the above embodiments may be implemented by hardware, or may be implemented by a program instructing relevant hardware, where the program may be stored in a computer-readable storage medium, and the above-mentioned storage medium may be a read-only memory, a magnetic disk or an optical disk, etc.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.