A method and device for predicting well-controlled reserves of heterogeneous buried-hill gas reservoirs

Abstract

The present invention discloses a method and device for predicting well-controlled reserves of a heterogeneous buried-hill gas reservoir, the method comprising: dividing the gas reservoir into N seepage areas along the radial direction of the wellbore according to the heterogeneity, the N seepage areas are distributed in concentric rings, and obtaining basic parameters of the N seepage areas; establishing a pressure propagation equation of the gas reservoir along the radial direction from the center of the concentric circles, and obtaining the well-controlled radius of the gas reservoir through the pressure propagation equation; and predicting well-controlled reserves using the well-controlled radius of the gas reservoir. The present application can take into account the characteristics of heterogeneous distribution of buried-hill gas reservoirs, is more consistent with the actual situation, and realizes accurate prediction of well-controlled reserves.

Description

Technical Field

[0001] The invention relates to oil and gas field development technology, and in particular to a method and device for predicting well-controlled reserves of a heterogeneous buried-hill gas reservoir. Background Art

[0002] In recent years, buried hill oil and gas reservoirs have become an important exploration and development area for finding new oil and gas fields in the field of petroleum geology at home and abroad. Buried hill oil and gas reservoirs have gradually become the most promising reserve and production successor area in China. In the process of oil and gas field development, well-controlled reserves are an important parameter in development design, but the calculation of well-controlled reserves in the existing technology assumes that the reservoir is homogeneously distributed, without considering the characteristics of heterogeneous distribution of the reservoir.

[0003] Therefore, in view of the heterogeneous distribution characteristics of buried-hill gas reservoirs, the well-controlled reserves prediction method in the existing technology can no longer meet the needs of development. Therefore, it is urgent to study the well-controlled reserves of heterogeneous gas reservoirs.

[0004] Based on this, the present invention provides a method and device for predicting the well-controlled reserves of a heterogeneous buried-hill gas reservoir, which fully considers the characteristics of heterogeneous distribution of reservoir permeability and can more accurately predict the well-controlled reserves of the buried-hill gas reservoir. Summary of the invention

[0005] The purpose of the present invention is to provide a method and device for predicting well-controlled reserves of a heterogeneous buried-hill gas reservoir, so as to take into account the heterogeneity of the reservoir.

[0006] The specific technical solution of the embodiment of the present invention is:

[0007] In a first aspect, the present invention provides a method for predicting well-controlled reserves of a heterogeneous buried-hill gas reservoir, comprising:

[0008] (1) According to the heterogeneity, the gas reservoir is divided into N seepage areas along the radial direction of the wellbore, and the N seepage areas are distributed in concentric rings, and the basic parameters of the N seepage areas are obtained;

[0009] (2) Establish a pressure propagation equation of the gas reservoir in the radial direction from the center of the concentric circle, and obtain the well control radius of the gas reservoir through the pressure propagation equation;

[0010] (3) Use the well control radius of the gas reservoir to predict the well controlled reserves.

[0011] Preferably, the basic parameters include permeability, porosity, fluid viscosity, and compressibility.

[0012] Preferably, the step establishes a pressure propagation equation of the gas reservoir in the radial direction from the center of the concentric circles, wherein the pressure propagation equation is:

[0013]

[0014] in,

[0015]

[0016]

[0017] In the formula, η is the pressure conductivity coefficient; k is the permeability; φ is the porosity; μ is the fluid viscosity; r is the radial radius; t is the time it takes for the pressure wave to reach the radial radius; j and k are subscripts, indicating the number of the seepage area, where j = 1, 2, ·····3·····N, k = 2, 3, ····N.

[0018] Preferably, the method of predicting well-controlled reserves by using the well-controlled radius of the gas reservoir also includes predicting well-controlled reserves by using a volumetric method.

[0019] Preferably, the volumetric method is used to predict well-controlled reserves, and the calculation method is:

[0020]

[0021] Where G is the well-controlled reserves, S g is the gas saturation, B g is the gas volume coefficient.

[0022] In a second aspect, the present invention provides a device for predicting well-controlled reserves of a heterogeneous buried-hill gas reservoir, comprising:

[0023] (1) a basic parameter acquisition module and a reservoir division module, wherein the reservoir division model is used to divide the gas reservoir into N seepage areas along the radial direction of the wellbore according to the heterogeneity, and the N seepage areas are distributed in concentric rings, and the basic parameter acquisition module is used to obtain basic parameters of the N seepage areas;

[0024] (2) a well control radius acquisition module, which is used to establish a pressure propagation equation of the gas reservoir from the center of the concentric circle along the radial direction, and obtain the well control radius of the gas reservoir through the pressure propagation equation;

[0025] (3) A well-controlled reserve prediction module, which is used to predict well-controlled reserves using the well-controlled radius of the gas reservoir.

[0026] Preferably, the basic parameters include permeability, porosity, fluid viscosity, and compressibility.

[0027] Preferably, when the well control radius acquisition module establishes a pressure propagation equation of a gas reservoir from the center of the concentric circles along the radial direction, the pressure propagation equation is:

[0028]

[0029] in,

[0030]

[0031]

[0032] In the formula, η is the pressure conductivity coefficient; k is the permeability; φ is the porosity; μ is the fluid viscosity; r is the radial radius; t is the time it takes for the pressure wave to reach the radial radius; j and k are subscripts, indicating the number of the seepage area, where j = 1, 2, ·····3·····N, k = 2, 3, ····N.

[0033] Preferably, the well-controlled reserves prediction module uses a volumetric method to predict well-controlled reserves.

[0034] Preferably, the volumetric method is used to predict well-controlled reserves, and the calculation method is:

[0035]

[0036] Where G is the well-controlled reserves, S g is the gas saturation, B g is the gas volume coefficient.

[0037] In summary, the present invention has the following advantages: the improved technical solution fully considers the characteristics of the heterogeneous distribution of the buried hill gas reservoir, establishes a prediction equation for the well control radius through the transmission process of the pressure wave, and then uses the volumetric method to predict the well controlled reserves after obtaining the well control radius. The situation considered is more in line with reality, which helps to guide the prediction of well controlled reserves of heterogeneous buried hill gas reservoirs. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0039] Figure 1 It is a schematic diagram of the reservoir physical model of the heterogeneous buried-hill gas reservoir. DETAILED DESCRIPTION

[0040] The details of the present invention can be more clearly understood with reference to the accompanying drawings and the description of the specific embodiments of the present invention. However, the specific embodiments of the present invention described herein are only used for the purpose of explaining the present invention and cannot be understood as limiting the present invention in any way. Under the guidance of the present invention, technicians can conceive of any possible variations based on the present invention, which should all be considered to belong to the scope of the present invention.

[0041] The terms "first", "second", etc. in the specification and claims of the present invention are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0042] In order to study the seepage law of buried hill gas reservoirs, it is necessary to first establish a corresponding physical model. The physical model conditions established in this application are as follows: The physical model of the heterogeneous buried hill gas reservoir is as follows: Figure 1 As shown in the figure, it is assumed that the heterogeneous buried-hill gas reservoir is composed of N concentrically distributed radial regions. In each region, the reservoir is homogeneously distributed. The regions from the center of the circle to the inside and outside are divided into the "first region", "second region", ... "Nth region" in sequence, and the distance from each region to the center of the circle is r1, r2, ..., r N . The radius r N is the outer boundary of the reservoir, so it can also be written as re. The process of gas propagation satisfies the basic principles of seepage mechanics, and the preset seepage assumptions are: single-phase, slightly compressible fluid seepage; the seepage direction is planar radial flow; the influence of gravity and capillary force is ignored; the seepage is Darcy linear seepage; the wellbore storage effect and skin effect are not considered; the reservoir thickness is a uniform thickness reservoir.

[0043] When a production well is arranged at the center of the circle to produce at a fixed rate, the pressure wave first propagates from the first area to the boundary with the second area, and then continues to propagate after reaching the second area until it propagates to the third area..., and then propagates outward in sequence until it propagates to the outer boundary, which is the well control radius of the gas reservoir.

[0044] The calculation equation of the gas reservoir well control radius is established through the above pressure propagation process:

[0045]

[0046] in,

[0047]

[0048]

[0049] In the formula, η is the pressure conductivity coefficient; k is the permeability; φ is the porosity; μ is the fluid viscosity; r is the radial radius; t is the time it takes for the pressure wave to reach the radial radius; j and k are subscripts, indicating the number of the seepage area, where j = 1, 2, ·····3·····N, k = 2, 3, ····N.

[0050] When there is only one region, the reservoir is a homogeneous region, and equation (1) can be written as:

[0051]

[0052] When there are two inhomogeneous regions, equation (1) can be written as:

[0053]

[0054] r 2 (t)-2r1 2 lnr(t)-r1 2 +2r1 2 lnr1=4η2(t-t1),(r1≤r,t1≤t)

[0055]

[0056] When there are three inhomogeneous regions, equation (1) can be written as:

[0057]

[0058] r 2 (t)-2r1 2 lnr(t)-r1 2 +2r1 2 lnr1=4η2(t-t1),(r1≤r≤r2,t1≤t≤t2)

[0059] r 2 (t)-2r2 2 lnr(t)-r2 2 +2r2 2 lnr2=4η3(t-t2),(r2≤r,t2≤t)

[0060] t1=r1 2 / (4η1),(j=1,2,3)

[0061]

[0062] By analogy, the well control radius of the heterogeneous buried hill gas reservoir in zone N can be calculated by equation (1).

[0063] After calculating the well control radius, the well control radius can be used to predict the well controlled reserves, and the volumetric method can be used for prediction.

[0064] The calculation formula of the volumetric method is:

[0065]

[0066] Where G is the well-controlled reserves, S g is the gas saturation, B g is the gas volume coefficient.

[0067] Specifically, when the center of the reservoir is a vertical well, the above method can be used directly to predict well-controlled reserves. When the center of the reservoir is a horizontal well, the equivalent wellbore method can be used to equate the seepage process of the horizontal well to the seepage process of the vertical well, so that prediction can be made from the above method, and the specific conversion process does not need to be repeated here.

[0068] The present invention has the following advantages: the improved technical solution fully considers the strong heterogeneity of the buried hill gas reservoir, thereby establishing a well-controlled reserve prediction model that is more in line with the actual formation conditions. The prediction model helps to further understand the heterogeneous seepage laws of the buried hill gas reservoir and provides theoretical guidance for field production at any time.

[0069] Although the specific implementation of the present invention is described in detail in conjunction with the drawings, it should not be understood as limiting the scope of protection of this patent. Within the scope described in the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

Claims

1. A method for predicting well-controlled reserves of a heterogeneous buried-hill gas reservoir, comprising: (1) According to the heterogeneity, the gas reservoir is divided into N seepage areas along the radial direction of the wellbore, and the N seepage areas are distributed in concentric rings, and the basic parameters of the N seepage areas are obtained; (2) Establish a pressure propagation equation for the gas reservoir in the radial direction from the center of the concentric circle, and obtain the well control radius of the gas reservoir through the pressure propagation equation; The pressure propagation equation is: in, Wherein, η is the pressure conductivity; k is the permeability; φ is the porosity; μ is the fluid viscosity; r is the radial radius; t is the time it takes for the pressure wave to reach the radial radius; j and k are subscripts, indicating the number of the seepage area, where j = 1, 2, ·····3·····N, k = 2, 3, ····N; (3) Using the volumetric method, the well-controlled reserves are predicted using the well-controlled radius of the gas reservoir: The calculation method is: Where G is the well-controlled reserves, S g is the gas saturation, B g is the gas volume coefficient.

2. A method for predicting well-controlled reserves of a heterogeneous buried-hill gas reservoir as described in claim 1, wherein the basic parameters include permeability, porosity, fluid viscosity, and compressibility.

3. A device for predicting well-controlled reserves of a heterogeneous buried-hill gas reservoir, comprising: (1) a basic parameter acquisition module and a reservoir division module, wherein the reservoir division module is used to divide the gas reservoir into N seepage areas along the radial direction of the wellbore according to the heterogeneity, and the N seepage areas are distributed in concentric rings, and the basic parameter acquisition module is used to obtain basic parameters of the N seepage areas; (2) a well control radius acquisition module, which is used to establish a pressure propagation equation of the gas reservoir from the center of the concentric circle along the radial direction, and obtain the well control radius of the gas reservoir through the pressure propagation equation; The pressure propagation equation is: in, Wherein, η is the pressure conductivity; k is the permeability; φ is the porosity; μ is the fluid viscosity; r is the radial radius; t is the time it takes for the pressure wave to reach the radial radius; j and k are subscripts, indicating the number of the seepage area, where j = 1, 2, ·····3·····N, k = 2, 3, ····N; (3) a well-controlled reserves prediction module, wherein the well-controlled reserves prediction module uses a volumetric method and a gas reservoir well-controlled radius to perform well-controlled reserves prediction. The calculation method is: Where G is the well-controlled reserves, S g is the gas saturation, B g is the gas volume coefficient.

4. A prediction device for well-controlled reserves of a heterogeneous buried-hill gas reservoir as described in claim 3, wherein the basic parameters include permeability, porosity, fluid viscosity, and compressibility.

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