Method for determining fault block reservoir oil-water interface based on water breakthrough time of oil well

Abstract

The application provides a method for determining the oil-water interface of a fault block reservoir based on the water breakthrough time of an oil well, which comprises the following steps: step 1, obtaining reservoir basic parameters; step 2, obtaining the properties of crude oil in the reservoir; step 3, obtaining oil well data; step 4, calculating the depth of the oil-water interface and determining the oil-water interface of the fault block reservoir. The method for determining the oil-water interface of a fault block reservoir based on the water breakthrough time of an oil well has the advantages that the oil-water interface is determined based on the water breakthrough time of the oil well, the required parameters are easy to obtain, the calculation is simple, fast and convenient, and the method has good guiding significance for the development scheme compilation, especially for a newly discovered reservoir, and has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field development engineering technology, and in particular to a method for determining the oil-water interface of a fault-block reservoir based on the water breakthrough time of an oil well. Background Technology

[0002] The oil-water interface refers to the interface between oil and water in an oil reservoir, usually characterized by its vertical depth. Above the interface is the oil-bearing zone, and below it is the water body. This parameter determines the reservoir's reserves and corresponding development strategies, making it crucial for reservoir development. Fault-block reservoirs typically have numerous sub-layers vertically, each generally possessing an independent oil-water interface. During oilfield development, the oil-water interface is usually determined through methods such as interpolation of oil-water layer pressure measurement data or multi-well extrapolation of oil-water layers based on well logging interpretation.

[0003] Chinese patent CN201710389361.3 discloses a method and apparatus for determining the location of the oil-water interface. The method includes: acquiring pressure measurement data at multiple water layer pressure measurement points and multiple oil layer pressure measurement points in a target section of the test area; the target section includes oil and water layers; the pressure measurement data includes measured formation pressure and formation depth; determining a target hydrostatic pressure gradient based on an initial hydrostatic pressure gradient set and the pressure measurement data at the multiple water layer pressure measurement points; determining the pressure reference surface pressure corresponding to the target section based on the target hydrostatic pressure gradient and the pressure measurement data at the multiple water layer pressure measurement points; and determining the oil-water interface location of the target section based on the pressure reference surface pressure, the target hydrostatic pressure gradient, and the pressure measurement data at the multiple oil layer pressure measurement points. This method requires pressure measurement data from both oil and water layers, and cannot be used to determine the oil-water interface for reservoirs where only oil layers have been encountered during drilling.

[0004] Chinese patent CN201910618258.0 discloses a method for determining the original oil-water interface in a developed fault-block reservoir. This method includes: Step 1, building a reservoir geological model; Step 2, evaluating the reservoir geological model based on the model; Step 3, estimating a series of initial oil-water interfaces based on geological research; Step 4, performing forward numerical simulation and matching of the reservoir; and Step 5, determining the oil-water interface and reserves. This method requires building and numerical modeling studies, determining the oil-water interface by estimating the numerical simulation results of multiple oil-water interfaces. Building the numerical model is time-consuming, requires a large amount of data, and the process is relatively cumbersome.

[0005] Chinese patent CN201710660938.X discloses a method and apparatus for determining the oil-water interface. The method includes: acquiring logging data, core data, and production data from a single well in a target area; performing feature analysis on the logging curves in the logging data to identify sand bodies and interlayers in the target area; determining the water-flooded layer in the sand body based on the logging data and core data; performing oil-water recovery processing on the sand body with the water-flooded layer based on the production data to obtain the oil-water interface before water flooding; and identifying the oil-water interface without interlayers in the pre-water flooding oil-water interface as the oil-water interface of the sand body. Because this scheme considers the influence of interlayers and water-flooded layers, it first identifies the sand bodies and interlayers in the target area; then determines the water-flooded layer in the sand body and performs oil-water recovery; and finally determines the oil-water interface in the sand body based on the influence of interlayers. Therefore, it solves the technical problems of inaccurate and large-error determination of the oil-water interface in existing methods.

[0006] Existing methods require high-quality data and generally take a long time. Existing technologies are quite different from the present invention and have failed to solve the technical problem we want to solve. Therefore, we have invented a new method for determining the oil-water interface of fault-block reservoirs based on the water breakthrough time of oil wells. Summary of the Invention

[0007] The purpose of this invention is to provide a method for determining the oil-water interface of a fault-block reservoir based on the water breakthrough time of an oil well, which is characterized by its ease of use, rapid calculation, and high efficiency.

[0008] The objective of this invention can be achieved through the following technical measures: a method for determining the oil-water interface of a fault-block reservoir based on the water breakthrough time of an oil well, the method comprising:

[0009] Step 1: Obtain basic reservoir parameters;

[0010] Step 2: Obtain the properties of the crude oil in the reservoir;

[0011] Step 3, acquire oil well data;

[0012] Step 4: Calculate the oil-water interface depth to determine the oil-water interface of the fault-block reservoir.

[0013] The objective of this invention can also be achieved through the following technical measures:

[0014] In step 1, the basic reservoir parameters are obtained through seismic data and well logging interpretation data.

[0015] In step 1, the reservoir basic parameters include:

[0016] (1) Average formation thickness of the reservoir;

[0017] (2) Average formation dip angle of the reservoir;

[0018] (3) Average porosity of the reservoir.

[0019] In step 2, the crude oil properties data of the reservoir are obtained through experimental testing.

[0020] In step 2, the crude oil property data of the reservoir includes:

[0021] (1) Crude oil underground viscosity, density, and volume coefficient;

[0022] (2) Data on oil-water interpenetration.

[0023] In step 3, the oil well data comes from drilling data and development and production data.

[0024] In step 3, the oil well data includes:

[0025] (1) Vertical depth of the reservoir encountered by the water-bearing oil well;

[0026] (2) The distance between the water-bearing oil well and the adjacent oil well;

[0027] (3) The average daily fluid production of the water-bearing oil wells before water breakthrough and the number of production days before water breakthrough.

[0028] Step 4 includes:

[0029] Step 41, calculate the oil-water interface depth using equation (1);

[0030] Step 42, calculate f in equation (1) using equation (2). w ′(s wf );

[0031] Step 43: Calculate the equivalent underground production of the oil well using equation (3);

[0032]

[0033]

[0034]

[0035] In the above formula, D woc D represents the depth of the oil-water interface, in meters (m). p T is the vertical depth when the oil well encounters the oil layer, in meters; T is the time to water breakthrough, in days; Q u The average daily underground fluid production before water breakthrough in the oil well is expressed in m. 3 / d; Q is the daily surface fluid production before water breakthrough in the oil well, t / d; ρ o The ground density of crude oil is expressed in g / cm³. 3 B oθ is the crude oil volume factor; θ is the reservoir dip angle, °; Φ is the average reservoir porosity, decimal; d is the distance between the water-bearing well and the adjacent well, m; h is the average reservoir thickness, m; f w s represents the water cut of the oil well, a decimal. wf The water saturation at the production end at the moment of water exposure, decimal; s wc The value represents the reservoir's bound water saturation, a decimal.

[0036] This invention presents a method for determining the oil-water interface in fault-block reservoirs based on the water-break time of oil wells. Based on the non-piston two-phase flow theory, it determines the reservoir's oil-water interface by identifying several data points, including basic reservoir parameters, crude oil properties, and pre-water-break production data. The method calculates the distance of the oil layer that flowed before water-break, thus determining the reservoir's oil-water interface. This method requires few parameters, is simple to use, and is fast and efficient, enabling rapid and accurate calculation of reservoir reserves and providing a basis for the development planning of new areas. This method does not require pressure measurement data from wells simultaneously encountering oil and water layers, nor does it require a large amount of data or numerical modeling studies. Determining the oil-water interface based on the water-break time of oil wells is easy to obtain, and the calculation is simple and quick. It can rapidly calculate oil-water interface data, thereby quickly obtaining reservoir reserves. This has significant guiding value for development planning, especially for newly discovered reservoirs, and its application prospects are broad. Attached Figure Description

[0037] Figure 1 This is a flowchart of a specific embodiment of the method for determining the oil-water interface of a fault-block reservoir based on the water breakthrough time of an oil well according to the present invention;

[0038] Figure 2 This is a schematic diagram of the reservoir basic parameters in the calculation formula of the method for determining the oil-water interface of a fault-block reservoir based on the water breakthrough time of an oil well, according to a specific embodiment of the present invention.

[0039] Figure 3 This is a structural well location diagram of a specific embodiment of the present invention;

[0040] Figure 4 This is a moisture content curve diagram of a specific embodiment of the present invention;

[0041] Figure 5 This is a diagram of oil well production curves according to a specific embodiment of the present invention. Detailed Implementation

[0042] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0043] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, and / or combinations thereof.

[0044] The method of the present invention for determining the oil-water interface of a fault-block reservoir based on the water breakthrough time of an oil well includes:

[0045] Step 1: Obtain basic reservoir parameters;

[0046] Step 2: Obtain the properties of the crude oil in the reservoir;

[0047] Step 3, acquire oil well data;

[0048] Step 4: Calculate the oil-water interface depth to determine the oil-water interface of the fault-block reservoir.

[0049] The following are several specific embodiments of the application of the present invention.

[0050] Example 1

[0051] In a specific embodiment 1 of the present invention, the method for determining the oil-water interface of a fault-block reservoir based on the water breakthrough time of an oil well includes the following steps:

[0052] In step 1, the basic reservoir parameters are obtained. These parameters can be obtained from seismic data and well logging interpretation data, and include:

[0053] (1) Average formation thickness of the reservoir;

[0054] (2) Average formation dip angle of the reservoir;

[0055] (3) Average porosity of the reservoir.

[0056] In step 2, crude oil property data from the reservoir is obtained. Crude oil property data is generally obtained through experimental testing and includes:

[0057] (1) Crude oil underground viscosity, density, and volume coefficient;

[0058] (2) Data on oil-water interpenetration.

[0059] In step 3, oil well data is acquired. Oil well data originates from drilling data and development / production data, including:

[0060] (1) Vertical depth of the reservoir encountered by the water-bearing oil well;

[0061] (2) The distance between the water-bearing oil well and the adjacent oil well;

[0062] (3) The average daily fluid production of the water-bearing oil wells before water breakthrough and the number of production days before water breakthrough.

[0063] In step 4, the oil-water interface depth is calculated. This is done using equations (1) and (2):

[0064] (1) Calculate the oil-water interface depth using equation (1);

[0065] (2) f in equation (1) is obtained by calculating f using equation (2). w ′(s wf );

[0066] (3) The equivalent underground production of the oil well is obtained by formula (3).

[0067]

[0068]

[0069]

[0070] In the above formula, D woc D represents the depth of the oil-water interface, in meters (m). p T is the vertical depth when the oil well encounters the oil layer, in meters; T is the time to water breakthrough, in days; Q u The average daily underground fluid production before water breakthrough in the oil well is expressed in m. 3 / d; Q is the daily surface fluid production before water breakthrough in the oil well, t / d; ρ o The ground density of crude oil is expressed in g / cm³. 3 B o θ is the crude oil volume factor; θ is the reservoir dip angle, °; Φ is the average reservoir porosity, decimal; d is the distance between the water-bearing well and the adjacent well, m; h is the average reservoir thickness, m; f w s represents the water cut of the oil well, a decimal. wf The water saturation at the production end at the moment of water exposure, decimal; s wc The reservoir bound water saturation is a decimal. Figure 2 This is a schematic diagram of the basic reservoir parameters in the formula.

[0071] Example 2

[0072] In a specific embodiment 2 of the present invention, such as Figure 1 As shown, Figure 1 This is a flowchart of a specific embodiment of a method for determining the oil-water interface of a fault-block reservoir based on the water breakthrough time of an oil well according to the present invention.

[0073] In step 101, basic reservoir parameters are obtained. Based on well logging data and structural interpretation data, the average effective thickness of the reservoir encountered by well Su1-2 is determined to be 3.6m, the formation dip angle is 3°, and the porosity is 0.298.

[0074] In step 102, crude oil property data from the reservoir is obtained. Through analysis of crude oil samples, the density of the surface crude oil is found to be 0.8274 g / cm³. 3 The volume factor is 1.08 and the viscosity of the underground crude oil is 4.051 mPa·s.

[0075] In step 103, oil well data is acquired. Based on geological research results, such as... Figure 3 The image shows the reservoir structure and well location map after the block geological study. The reservoir oil-water interface is predicted to be 1372m deep based on seismic data. The vertical depth of the reservoir encountered by well Su1-2 is 1357.8m, the distance from surrounding wells is 400m, the daily fluid production before water breakthrough is 26.1t / d, and the number of days since water breakthrough is 1731 days. Production data can be found in [link to production data]. Figure 5 .

[0076] In step 104, the above parameters are substituted into equations (1), (2), and (3). The relevant parameters in equation (2) are obtained by graphical method based on the relative permeability data moisture content curve, such as... Figure 4 As shown, draw a tangent line from the endpoint of bound water saturation to the water content curve. The x and y coordinates of the tangent point are s. wf f w (s wf In the embodiment, the relevant data required for equation (2) are s wf =0.42, s wc =0.25, f w (s wf =0.63, and the production data in equation (3) is obtained by averaging the production data of this well, such as Figure 5 As shown, the oil-water interface is calculated by substituting the relevant data obtained from equations (2) and (3) into equation (1). According to the calculation, the oil-water interface of the embodiment is 1380.7m, which is 8.7m deeper than the earthquake reservoir prediction data.

[0077]

[0078]

[0079]

[0080] This embodiment later underwent numerical modeling studies. During the numerical simulation, the oil-water interface was adjusted to 1379.5m based on historical fitting data. The results were very close to those of the present invention, reflecting the better accuracy of the present invention. Compared with the present invention, numerical simulation requires a significant amount of time and sufficient production data as fitting observation data. The present invention is faster, more efficient, and its accuracy meets the requirements for reservoir understanding, making it more advantageous.

[0081] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0082] Except for the technical features described in the specification, all other technologies are known to those skilled in the art.

Claims

1. A method for determining the oil-water interface of a fault-block reservoir based on the water breakthrough time of an oil well, characterized in that, The method for determining the oil-water interface of a fault-block reservoir based on the water breakthrough time of the oil well includes: Step 1: Obtain basic reservoir parameters; Step 2: Obtain the properties of the crude oil in the reservoir; Step 3, acquire oil well data, the oil well data including: (1) Vertical depth of the reservoir encountered by the water-bearing oil well; (2) The distance between the water-bearing oil well and the adjacent oil well; (3) The average daily fluid production of the water-bearing oil well before water breakthrough and the number of production days before water breakthrough; Step 4: Calculate the oil-water interface depth to determine the oil-water interface of the fault-block reservoir; Step 4 includes: Step 41, calculate the oil-water interface depth using equation (1); Step 42, calculate the value in equation (1) using equation (2). ; Step 43: Calculate the equivalent underground production of the oil well using equation (3); （1） （2） （3） In the above formula, The depth of the oil-water interface, in meters (m). is the vertical depth when the oil well encounters the oil layer, in meters; T is the time to water breakthrough in the oil well, in days. The average daily underground fluid production before water breakthrough in the oil well is expressed in m. 3 / d; Q is the daily surface fluid production before the oil well reaches water, t / d; The ground density of crude oil is expressed in g / cm³. 3 ; This is the crude oil volume coefficient; The reservoir dip angle is expressed in °. denoted as the average reservoir porosity (decimal); d represents the distance between the water-bearing well and the adjacent well (m); h represents the average reservoir thickness (m). This represents the water cut of the oil well, a decimal. The water saturation at the production end at the moment of water exposure is a decimal. The value represents the reservoir's bound water saturation, a decimal.

2. The method for determining the oil-water interface of a fault-block reservoir based on the water breakthrough time of an oil well, as described in claim 1, is characterized in that... In step 1, the basic reservoir parameters are obtained through seismic data and well logging interpretation data.

3. The method for determining the oil-water interface of a fault-block reservoir based on the water breakthrough time of an oil well, as described in claim 2, is characterized in that... In step 1, the reservoir basic parameters include: (1) Average formation thickness of the reservoir; (2) Average formation dip angle of the reservoir; (3) Average porosity of the reservoir.

4. The method for determining the oil-water interface of a fault-block reservoir based on the water breakthrough time of an oil well, as described in claim 1, is characterized in that... In step 2, the crude oil properties data of the reservoir are obtained through experimental testing.

5. The method for determining the oil-water interface of a fault-block reservoir based on the water breakthrough time of an oil well, as described in claim 4, is characterized in that... In step 2, the crude oil property data of the reservoir includes: (1) Crude oil underground viscosity, density, and volume coefficient; (2) Data on oil-water interpenetration.

6. The method for determining the oil-water interface of a fault-block reservoir based on the water breakthrough time of an oil well, as described in claim 1, is characterized in that... In step 3, the oil well data comes from drilling data and development and production data.

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