A method for predicting P-level reserves using single-well decline analysis
Through the single well decreasing analysis method, the problems of unreliability and uncertainty in the prediction of P-class reserves in the old oilfield are solved, and more objective and reliable reserve predictions are achieved, providing a reliable source of data for asset value evaluation.
Patent Information
- Application Number
- CN202110227480.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2021-03-02
- Publication Date
- 2025-03-28
- Estimated Expiration
- 2041-03-02
AI Technical Summary
The existing technology has problems in the prediction of P-level reserves in the old oilfields, such as unreliable, uncertain and poor inheritance, which affects the objectivity of asset value evaluation.
The single well decreasing analysis method is used to draw a dynamic data curve for single well development, select the output decreasing segment, count the time and output initial values of different decreasing stages, determine the decreasing type and decreasing rate, and conduct P-level reserve prediction.
It improves the objectivity and reliability of reserve forecasts, reduces subjectivity, enhances the inheritance of reserve forecasts, and provides a reliable source of data for asset value evaluation.
Smart Images
Figure CN114991743B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to an old oilfield asset value evaluation method, and in particular to a method for predicting P-level reserves by applying single-well decline analysis. Background Art
[0002] P-level reserve prediction is the core of asset value evaluation of oil and gas field development projects at home and abroad, and directly determines the investment returns of oil and gas field development projects and the formulation of subsequent development decisions.
[0003] At present, in the process of predicting P-level reserves of old oil fields at home and abroad, software methods are generally used. The advantages are high efficiency in data collection and processing. As long as the evaluators know how to use the software, they can complete the reserve prediction. It is highly recognized by domestic and foreign companies and is convenient for project cooperation negotiations. However, there are also major problems in using software methods for reserve prediction. First, the selection and regression fitting of historical data are highly subjective. If the evaluators do not understand the production dynamics of the oil field, it is easy to have a large deviation between the predicted data and the actual production, which directly affects the asset value evaluation; second, the software method has great uncertainty, and the inheritance of the reserve prediction results is poor. Once the evaluators change, the reserve prediction results will change due to subjective factors, which is not conducive to the objective evaluation of asset value.
[0004] In order to solve the above problems, it is necessary to find a new P-level reserve prediction method, which can not only more objectively evaluate the asset value of old oil fields and provide a reliable basis for investment decisions, but also form a replicable standard method to enhance the inheritability of old oil field reserve prediction work and facilitate its promotion and application in other oil fields. There is no report on solving this problem yet. Summary of the invention
[0005] The main purpose of the present invention is to provide a new method for predicting P-level reserves of old oil fields by using single well decline analysis, so as to solve the problems of unreliable reserve prediction results, large uncertainty and poor inheritance of reserve prediction methods in the process of reserve prediction of old oil fields by using a single application software method, provide a practical standard method for predicting P-level reserves of old oil fields, realize objective evaluation of the value of oil and gas field assets, and provide a basis for correct decision-making on development plans.
[0006] To achieve the above object, the present invention adopts the following technical solutions:
[0007] The present invention provides a method for predicting P-level reserves by applying single-well decline analysis, which comprises the following steps: drawing a single-well development dynamic data curve, performing development dynamic analysis, selecting a production decline segment, and counting the time to enter different decline stages and the initial value of production; determining the decline type, decline rate and correlation coefficient of different stages; and predicting P-level reserves.
[0008] Furthermore, the production stage that can reflect the current production characteristics and rules of the oil well is selected as the 1P decline section; the production stage in the history of the well with a working system similar to 1P but a slower decline is selected as the 2P decline section; the production stage in the history of the well with a more stable production and a further slower decline is selected as the 3P decline section.
[0009] Furthermore, for wells that have entered a clear decline period and are of the exponential decline type, the reserves predicted according to the exponential decline trend to the end of the evaluation period are used as 1P reserves; the reserves predicted according to the exponential decline to the time when hyperbolic decline occurs + the reserves predicted according to the hyperbolic decline to the end of the evaluation period are used as 2P reserves; the reserves predicted according to the exponential decline to the time when hyperbolic decline occurs + the reserves predicted according to the hyperbolic decline to the time when harmonic decline occurs + the reserves predicted according to the harmonic decline to the end of the evaluation period are used as 3P reserves.
[0010] Furthermore, for wells that have entered a clear decline period and are of the hyperbolic decline type, the reserves predicted to the end of the evaluation period according to the hyperbolic decline trend are taken as 1P reserves; the reserves predicted to the time of harmonic decline according to the hyperbolic decline + the reserves predicted to the end of the evaluation period according to the harmonic decline are taken as 2P reserves; 3P reserves = 2P reserves.
[0011] Furthermore, for wells that have entered a clear decline period and are of the harmonic decline type, the reserves predicted to the end of the evaluation period are taken as 1P reserves according to the harmonic decline trend; 3P reserves = 2P reserves = 1P reserves.
[0012] Furthermore, for wells that have not entered an obvious decline period at this stage, the analogy method of similar development stages of the same well or adjacent wells is used to first determine their decline type and decline parameters, and then conduct P-level reserves prediction.
[0013] Compared with the prior art, the present invention has the following advantages:
[0014] The P-level reserve prediction in the method of the present invention is a prediction of future development trends based on a comprehensive understanding and grasp of the development dynamics and development laws of oil fields, oil reservoirs and single wells. The reserve prediction results are more objective and reliable, and the method has clear ideas, simple operation, and is easy for reserve assessment personnel to master. It can provide a reliable reserve data source for asset value evaluation of domestic and foreign oil field projects.
[0015] The method of the present invention was applied in a certain oil field in 2020. A total of 96 producing wells were predicted for P-level reserves, and the reserve prediction results of previous years were compared and analyzed one by one. The results were more in line with the actual development of the oil field, and provided a decision-making basis for the formulation of subsequent development planning and development plans of the oil field, which can greatly improve the investment efficiency of assets. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.
[0017] Figure 1 The typical well development curve and decline segment selection diagram described in Example 1 of the present invention;
[0018] Figure 2 The 1P reserve prediction curve and result diagram of the typical well described in Example 1 of the present invention;
[0019] Figure 3 The 2P reserve prediction curve and result diagram of the typical well described in Example 1;
[0020] Figure 4 This is the 3P reserve prediction curve and result diagram of the typical well described in Example 1. DETAILED DESCRIPTION
[0021] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.
[0022] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations and / or combinations thereof.
[0023] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.
[0024] Example 1
[0025] A method for predicting P-level reserves by using single well decline analysis, the method comprising the following steps:
[0026] (1) Draw something similar Figure 1 The single well development dynamic data curve is used to conduct development dynamic analysis, and on this basis, the production decline section is selected. The production stage that can reflect the current production characteristics and laws of the oil well is selected as the 1P decline section; the production stage in the history of this well with a similar working system to 1P but a slower decline is selected as the 2P decline section; the production stage in the history of this well with more stable production and further slower decline is selected as the 3P decline section.
[0027] (2) Use OFM software to Figure 1 The production data of the 1P, 2P and 3P decline stages were selected for output fitting. According to the correlation coefficient, the 1P, 2P and 3P decline types were determined to be exponential decline, hyperbolic decline and harmonic decline respectively. The time to enter different decline stages and the initial value of output were counted.
[0028] (3) Based on Figure 1 Select the 1P decreasing stage and establish a similar Figure 2 The decline prediction model is used to determine the decline rate, correlation coefficient and other parameters, and the reserves are predicted to the end of the evaluation period as 1P reserves according to the exponential decline trend;
[0029] (4) Based on Figure 1 The selected 2P decreasing stage, combined with the time corresponding to entering 2P and the initial value of output, establishes a similar Figure 3 The decline prediction model is used to determine the decline rate, correlation coefficient and other parameters, and the time when hyperbolic decline occurs is predicted according to the exponential decline + the time when hyperbolic decline occurs is predicted according to the hyperbolic decline to the end of the evaluation period as the 2P reserves.
[0030] (5) Based on Figure 1 The selected 3P decreasing stage, combined with the time corresponding to entering 3P and the initial value of output, establishes a similar Figure 4 The decline prediction model is used to determine the decline rate, correlation coefficient and other parameters, and the time when the hyperbolic decline occurs is predicted according to the exponential decline + the time when the harmonic decline occurs is predicted according to the hyperbolic decline + the time when the harmonic decline occurs is predicted according to the harmonic decline as the end of the evaluation period as the 3P reserves.
[0031] Example 2
[0032] A method for predicting P-level reserves by using single well decline analysis, the method comprising the following steps:
[0033] (1) Draw a single well development dynamic data curve, conduct development dynamic analysis, and select the production decline segment on this basis. The production stage that can reflect the current production characteristics and laws of the oil well is selected as the 1P decline segment; the production stage in the history of the well with a similar working system to the 1P but a slower decline is selected as the 2P decline segment; the production stage in the history of the well with more stable production and a further slower decline is selected as the 3P decline segment.
[0034] (2) The OFM software was used to fit the production data of the selected 1P, 2P, and 3P decline stages. The 1P and 2P decline types were determined as hyperbolic decline and harmonic decline according to the correlation coefficient, and the time to enter different decline stages and the initial value of output were counted.
[0035] (3) According to the selected 1P decline stage, a decline prediction model is established to determine the decline rate, correlation coefficient and other parameters, and the 1P reserves are predicted to the end of the evaluation period according to the hyperbolic decline trend;
[0036] (4) According to the selected 2P decline stage, combined with the time corresponding to entering 2P and the initial value of production, a decline prediction model is established to determine the decline rate, correlation coefficient and other parameters, and the time of the occurrence of harmonic decline predicted according to hyperbolic decline + the time of the end of the evaluation period predicted according to harmonic decline is taken as the 2P reserves. 3P reserves = 2P reserves.
[0037] Example 3
[0038] A method for predicting P-level reserves by using single well decline analysis, the method comprising the following steps:
[0039] (1) Draw a single well development dynamic data curve, conduct development dynamic analysis, and select the production decline segment on this basis. The production stage that can reflect the current production characteristics and laws of the oil well is selected as the 1P decline segment; the production stage in the history of the well with a similar working system to the 1P but a slower decline is selected as the 2P decline segment; the production stage in the history of the well with more stable production and a further slower decline is selected as the 3P decline segment.
[0040] (2) OFM software was used to fit the production data of the selected 1P, 2P, and 3P decline stages, and the 1P decline type was determined to be harmonic decline based on the correlation coefficient.
[0041] (3) Based on the selected 1P decline stage, a decline prediction model is established to determine parameters such as the decline rate and correlation coefficient, and the 1P reserves are predicted to the end of the evaluation period according to the harmonic decline trend; 3P reserves = 2P reserves = 1P reserves.
[0042] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.
Claims
1. A method for predicting P-level reserves using single well decline analysis, characterized in that: The following steps are involved: Draw a single well development dynamic data curve, conduct development dynamic analysis, select the production decline segment, and count the time to enter different decline stages and the initial production value; Determine the decline type, decline rate and correlation coefficient at different stages; make P-level reserve prediction; The production stage that can reflect the current production characteristics and laws of the oil well is selected as the 1P decline stage; the production stage in the history of the well with a similar working system to 1P but a slower decline is selected as the 2P decline stage; the production stage in the history of the well with more stable production and a further slower decline is selected as the 3P decline stage; For wells that have entered an obvious decline period and are of the exponential decline type, the reserves predicted according to the exponential decline trend to the end of the evaluation period are regarded as 1P reserves; the reserves predicted according to the exponential decline to the time of hyperbolic decline + the reserves predicted according to the hyperbolic decline to the end of the evaluation period are regarded as 2P reserves; the reserves predicted according to the exponential decline to the time of hyperbolic decline + the reserves predicted according to the hyperbolic decline to the time of harmonic decline + the reserves predicted according to the harmonic decline to the end of the evaluation period are regarded as 3P reserves; For wells that have entered a period of obvious decline and are of the hyperbolic decline type, the reserves predicted according to the hyperbolic decline trend to the end of the evaluation period are taken as 1P reserves; the reserves predicted according to the hyperbolic decline to the time of occurrence of harmonic decline + the reserves predicted according to the harmonic decline to the end of the evaluation period are taken as 2P reserves; 3P reserves = 2P reserves; For wells that have entered a significant decline period and are of the harmonic decline type, the reserves predicted to the end of the evaluation period according to the harmonic decline trend are taken as 1P reserves; 3P reserves = 2P reserves = 1P reserves; For wells that have not entered a clear decline period at this stage, the analogy method of similar development stages of the same well or adjacent wells is used to first determine their decline type and decline parameters, and then conduct P-level reserves prediction.