CN110359903A - A Method for Determining the Irregular Geometric Boundary of a Closed Gas Reservoir - Google Patents

Abstract

The invention discloses a method for determining an irregular geometric boundary of a closed gas reservoir, which comprises the steps of firstly selecting a plurality of groups of boundary models for fitting according to the pressure recovery log-log curve characteristics of gas wells distributed on the boundary and combining the existing reliable geological knowledge of boundary wells; then, screening a boundary model according to a fitting result; then, establishing a gas well production dynamic analysis model according to the screened boundary model, circularly debugging key parameters to fit m (RNP) and derivatives thereof, PI (proportional integral) and point (Point) and derivatives thereof, and finally determining a gas well model and a boundary form; and finally combining the boundary forms of all boundary gas wells to obtain the irregular geometric boundary of the gas reservoir. The invention adopts the edge-exploring test interpretation technology, and repeatedly interprets and verifies the pressure recovery data of the wells around the boundary in combination with the production dynamic data to obtain the irregular boundary of the gas reservoir, thereby solving the problem that the actual boundary of the gas reservoir is complex and cannot be accurately interpreted, and providing an important basis for determining the gas field development scheme and the development mode.

Description

A Method for Determining the Irregular Geometric Boundary of a Closed Gas Reservoir

technical field

The invention belongs to the technical field of gas field development, and in particular relates to a method for determining the irregular geometric boundary of a closed gas reservoir.

Background technique

Determining the nature and size of the boundary and solving the complexity of the boundary is an important basis for determining the development plan and method. The present invention mainly adopts the edge detection test combined with the production dynamics to determine the irregular boundary of the gas reservoir.

The edge test was first proposed by Jones in 1956, and generally refers to "limited well test" or "Extended well test". Jones provided a complete theoretical basis for the edge test, after which many researchers have done a lot of work in this field. Due to the development of computer technology, the international edge detection test developed rapidly in the late 1970s, and further development was made on the basis of oilfield development and well testing technology. Through edge testing, gas reservoir engineers can interpret dynamic data more profoundly, mainly because they have a clearer understanding of gas reservoir boundary types and boundary sizes. However, currently commonly used models can only solve regular geometric boundary problems in edge testing. The boundaries of gas reservoirs are varied and cannot be fully described or approximated by conventionally tested models. Therefore, to solve the complexity of the boundary, new models and problem-solving methods must be developed.

The important difference between the edge detection test proposed this time and the conventional edge detection lies in the difference in the nature, shape and size of the boundary. It can give the numerical well test model of gas reservoirs with arbitrary shapes under different boundary conditions, and analyze the impact of different boundary properties on the test. The influence of the theoretical well curve and the influence of the boundary distance can explain the irregular geometric boundary of the gas reservoir.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for determining the irregular geometric boundaries of closed gas reservoirs to solve the problems of triangular gas reservoirs, arbitrary quadrilateral gas reservoirs, and gas reservoirs with arbitrary irregular geometric boundaries. Explain the problem.

The present invention adopts following technical scheme:

A method for determining the irregular geometric boundary of a closed gas reservoir, comprising the following steps:

S1. Collect on-site pressure data, daily production data, logging interpretation data, high-pressure physical property data and well diameter data, restore the double-logarithmic curve characteristics according to the pressure of the gas wells distributed on the boundary, and combine the existing reliable geological understanding of the boundary wells to select Multiple sets of boundary models are fitted;

S2. Screening the boundary model according to the fitting result;

S3. Establish a gas well production dynamic analysis model according to the boundary model screened in step S2, and cyclically debug key parameters to fit m(RNP) and its derivative, PI, PIint and its derivative curve, and finally determine the gas well model and boundary shape;

S4. Combining the boundary forms of all boundary gas wells to obtain the irregular geometric boundary of the gas reservoir.

Specifically, in step S1, the boundary model includes: homogeneous formation + three immobile boundaries, radial composite formation + infinite boundary, radial composite formation + three immobile boundaries, homogeneous formation + closed boundary.

Specifically, in step S2, according to the pressure recovery log-logarithmic curve characteristics of each well in the closed gas reservoir, multiple sets of boundary models are selected for fitting, and according to the fitted shape and the obtained well test interpretation results, the The regional stratigraphic thickness map and geological knowledge match more than 80% of the models, and a consistent boundary model is obtained.

Specifically, in step S3, combined with the pressure and production of the production dynamic data, the pressure recovery interpretation parameters of the screened boundary model are applied to the production performance data analysis, and the pressure recovery interpretation results are used as the input parameters of the dynamic analysis model to establish the production performance of the gas well Analytical model.

Further, the key parameters include formation coefficient, pollution coefficient, boundary distance and boundary length, m(RNP) is the production data, PI is the formation pressure data, PIint is the integral data of the formation pressure against time, for m(RNP) and its derivative Fitting curves, PI, PIint and their derivative curves are used to verify whether the screened boundary model conforms to the production performance characteristics, so as to determine the gas well model.

Specifically, in step S4, according to the distance between each well and the boundary, the length of the boundary, and the angle between the boundary, the boundary is drawn and cross-connected to obtain the irregular geometric boundary of the entire closed gas reservoir.

Compared with the prior art, the present invention has at least the following beneficial effects:

The present invention adopts the edge detection test interpretation technology, and repeatedly interprets and confirms the pressure recovery data of the wells around the boundary combined with the production dynamic data to obtain the irregular boundary of the gas reservoir, which solves the problem that the actual gas reservoir boundary is complex and cannot be accurately interpreted, and provides Provide an important basis for determining the gas field development plan and development method.

Furthermore, when selecting a preliminary multi-group boundary model for fitting according to the characteristics of the gas field, this is only the first step, and many fitting shapes will be obtained, as well as the same amount of interpretation results, which need to be further combined with the formation thickness Figures and geological features to preliminarily exclude some non-compliant combination boundaries, which is beneficial to determine the only consistent boundary later.

Furthermore, the general pressure recovery interpretation results will get a variety of interpretation results. In order to determine the uniqueness of the interpretation results, further verification is required. Therefore, it is necessary to combine the dynamic data of the gas well to establish a gas well production dynamic analysis model to determine the corresponding interpretation result model.

Further, according to the finally determined pressure interpretation result model, the number of boundaries around the well, as well as the length and angle degree can be obtained, as well as the distance relationship between the position of each well and the boundary, which is determined by the pressure interpretation model You can get it without calculating and drawing yourself. The boundaries of each well explained are drawn and cross-connected to obtain the irregular geometric boundaries of the entire closed gas reservoir.

In summary, the method of the present invention is easy to apply, can save a lot of manpower and financial resources, and has great practical value and economic value.

The technical solutions of the present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

Description of drawings

Fig. 1 is a schematic diagram of a double-logarithmic diagnosis curve of pressure recovery in well S224 according to an embodiment of the present invention;

Fig. 2 is a schematic diagram of each model interpretation model of well S224 in the embodiment of the present invention, wherein, (a) is a homogeneous formation + three immobile boundary maps, (b) is a radial composite formation + an infinite boundary map, and (c) is a radial Composite strata + three no-flow boundary maps, (d) is a homogeneous stratum + closed boundary map;

Fig. 3 is the schematic diagram of each model fitting curve of well S224 of the embodiment of the present invention;

Fig. 4 is the embodiment of the present invention m (RNP) and its derivative bilogarithmic fitting curve schematic diagram;

Fig. 5 is the embodiment of the present invention PI, PI integral and its derivative bilogarithmic fitting curve schematic diagram;

Fig. 6 is a schematic diagram of the internal dynamic boundary and the external lithological change boundary of the Shan 224 gas storage according to the embodiment of the present invention.

Detailed ways

A method for determining the irregular geometric boundary of a closed gas reservoir of the present invention comprises the following steps:

S1. Collect on-site pressure data, daily production data, logging interpretation data, high-pressure physical property data and well diameter data, restore the double-logarithmic curve characteristics according to the pressure of the gas wells distributed on the boundary, and combine the existing reliable geological understanding of the boundary wells to select Multiple sets of temporally consistent models are fitted;

Boundary models include: homogeneous formation + three immobile boundaries, radial composite formation + infinite boundary, radial composite formation + three immobile boundaries, homogeneous formation + closed boundary.

S2. Screening the boundary model according to the fitting result;

Aiming at the pressure recovery double-logarithmic curve characteristics of each well in the closed gas reservoir, the above multiple sets of boundary models were selected for fitting. The geological understanding matches more than 80% of the models, resulting in a conforming boundary model.

S3. Apply the pressure recovery interpretation parameters of the screened boundary model to the analysis of the production performance data of the well, combine the pressure and production of the production dynamic data, and use the pressure recovery interpretation results as the input parameters of the dynamic analysis model to establish a gas well production dynamic analysis Model, cyclically debug each key parameter to fit m(RNP) and its derivative, PI, PIint and its derivative curve, so that the actual production and pressure curve and the theoretical curve can achieve a matching effect of more than 80%, and finally determine the gas well Model and boundary shape;

The key parameters include: formation factor kh, pollution factor S and boundary distance Ri or boundary length L.

m(RNP) and its derivative curve, PI, PIint and its derivative curve are the fitting curves of the gas well production dynamic analysis model in Topaze software: m(RNP) is production data, PI is formation pressure data, PIint is formation pressure against time The integral data of m(RNP) and its derivative curve, PI, PIint and its derivative curve are fitted, mainly to verify which set of the screened boundary model is more in line with the production performance characteristics, so as to determine the gas well model.

Dynamic analysis uses Topaze software.

S4. Combining the boundary forms of all boundary gas wells to obtain the irregular geometric boundary of the gas reservoir.

Determine the single gas well model and boundary shape, draw the boundary and cross-connect it according to the distance between each well and the boundary, the length of the boundary, and the angle between the boundary, so as to obtain the irregular geometric boundary of the entire closed gas reservoir.

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. The components of the embodiments of the invention generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations. Accordingly, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

The boundary of the Shan 224 gas storage in the Jingbian gas field is relatively complicated, taking Well S224 on the boundary as an example

According to the characteristics of the double-logarithmic curve of pressure recovery, as shown in Figure 1, several sets of models were selected for fitting.

The boundary model includes: 1. Homogeneous formation + three immobile boundaries; 2. Radial composite formation + infinite boundary; 3. Radial composite formation + three immobile boundaries; 4. Homogeneous formation + closed boundary, as shown in Figure 2 shown.

For each model, the pressure recovery logarithmic curve is fitted as shown in Figure 3, and models 1, 2, and 4 are selected based on the original characteristic curve.

The specific parameters obtained after screening model fitting are shown in the table below:

In order to further verify the boundary characteristics of the gas well, we applied the model pressure recovery interpretation parameters selected above to the analysis of the production performance data of this well.

Please refer to Figure 4 and Figure 5. The dynamic analysis uses Topaze software, combined with the key parameters of the gas well explained by the pressure recovery test, to establish a dynamic analysis model of the gas well production, and to continuously debug the key parameters. For m(RNP) and its derivatives, PI, PIint And its derivative curve is fitted, and the following fitting results are obtained.

Finally, the rectangular closed boundary model is selected, and the fitting degree is good. The following is the obtained key parameter table within the control range of the gas well.

The determination table of key parameters of Well S224 is as follows:

The boundary of other wells on the boundary of the gas storage can be obtained in the same way. According to the distance between each well and the boundary, the length of the boundary, and the angle between the boundary, the boundary is drawn and cross-connected to obtain the boundary of the Shan 224 gas storage. The irregular geometric boundary is shown in Fig. 6. The three wells in the figure formed a dynamic boundary (the boundary line of the inner arrow) inside the well area during the production process. The distance between the wellbore and the dynamic boundary and the lithological change boundary has been confirmed by Topaze software. The dynamic boundary and lithological boundary together constitute the gas drainage range of each well, and also determine the dynamic reserves of each well.

The method of the present invention has been used in the Jingbian Gas Field, where the grooves are very dense and complex. The method can accurately judge the shape and direction of the grooves, and the success rate of drilling in the gas field has been increased from 70% to 85%. One well can Saved 13.28 million yuan (calculated according to the cost of vertical well drilling), and Jingbian saved 106 million yuan in drilling costs in 2016 alone, of which Jingbian planned to drill 35 wells and drilled 8 fewer wells.

The above content is only to illustrate the technical ideas of the present invention, and cannot limit the protection scope of the present invention. Any changes made on the basis of the technical solutions according to the technical ideas proposed in the present invention shall fall within the scope of the claims of the present invention. within the scope of protection.

Claims (6)

1. a kind of determination method for closing the irregular geometrical boundary of gas reservoir, which comprises the following steps:

S1, the pressure data of collection site, daily output data, log analysis data, high pressure property data and hole diameter data, root It is chosen more according to the gas well pressure recovery double logarithmic curve feature for being distributed in boundary in conjunction with the existing reliable geological knowledge of borderline well Group boundary model is fitted；

S2, boundary model is screened according to the result of fitting；

S3, gas well liquid loading dynamic analysis model, circulation debugging key parameter, with quasi- are established according to the boundary model that step S2 is screened M (RNP) and its derivative, PI, PIint and its derivative curve are closed, it is final to determine gas well model and border motif；

S4, the border motif for combining all boundary gas wells obtain the irregular geometrical boundary of gas reservoir.

2. a kind of determination method for closing the irregular geometrical boundary of gas reservoir according to claim 1, which is characterized in that step In S1, boundary model includes: homogeneous formation+three not flow boundary, radial compound stratum+infinity boundary, radial compound Layer+three not flow boundary, homogeneous formation+closed boundary.

3. a kind of determination method for closing the irregular geometrical boundary of gas reservoir according to claim 1, which is characterized in that step In S2, for the pressure recovery double logarithmic curve feature of the every mouth well in closing gas reservoir, chooses multiple groups boundary model and intended It closes, is matched as a result, choosing with wellblock formation thickness figure and geological knowledge according to the form of fitting and obtained well test analysis 80% or more model, the boundary model met.

4. a kind of determination method for closing the irregular geometrical boundary of gas reservoir according to claim 1, which is characterized in that step In S3, in conjunction with the pressure and yield of Production development data, the pressure buildup interpretation parameter for screening back boundary model is applied to life It produces in dynamic data analysis, establishes gas well liquid loading dynamic for pressure buildup interpretation result as the input parameter of model for dynamic analysis Analytic modell analytical model.

5. a kind of determination method for closing the irregular geometrical boundary of gas reservoir according to claim 4, which is characterized in that crucial Parameter includes formation capacity, contamination factor, frontier distance and boundary length, and m (RNP) is yield data, and PI is strata pressure number According to, PIint is the integration data that strata pressure is directed to the time, for m (RNP) and its derivative curve, PI, PIint and its derivative Curve is fitted, for verifying whether the boundary model after screening meets characteristic of production dynamic, so that it is determined that gas well model.

6. a kind of determination method for closing the irregular geometrical boundary of gas reservoir according to claim 1, which is characterized in that step In S4, according to every mouth well at a distance from boundary, boundary length and boundary angle, boundary is drawn and carries out intersection company It connects, obtains the irregular geometrical boundary for entirely closing gas reservoir.