CN110952976B - Single-well exploitation stable yield potential evaluation method in gas reservoir development mode - Google Patents

Abstract

The invention discloses a method for evaluating the stable production potential of single well exploitation in a gas reservoir development mode. Analyze and obtain the current reservoir pressure; calculate the pressure depletion degree of a single well; determine the annual average pressure depletion degree of a single well, which is the first evaluation parameter; use the Blasingame production decline analysis method, combined with the production decline dynamic analysis software, to fit the formation dynamic production changes The average annual depletion degree of a single well is determined based on the trend, cumulative production and other data; according to the average annual depletion degree and the average annual production degree of a single well, the stable production potential is evaluated. The invention adds a scientific evaluation index of stable production, and after comprehensively considering factors such as formation and production performance, there is a quantitative and scientific guiding method on how to stabilize the production of the gas reservoir.

Description

An evaluation method for stable production potential of single well exploitation under gas reservoir development mode

technical field

The invention relates to a method for evaluating the potential for stable production of single well exploitation in a gas reservoir development mode, and belongs to the technical field of petroleum exploration and development.

Background technique

Compared with coal and oil, natural gas has the characteristics of high combustion efficiency and low pollution, and is the most realistic clean energy in the 21st century. At present, the proportion of natural gas resources in the world's energy consumption structure is increasing. The world oil and natural gas industry has entered the era of large-scale natural gas development, and the efficient development of natural gas resources has become an inevitable trend and only way for the development of world oil and natural gas. my country's natural gas resources have great potential and wide distribution, and major breakthroughs have been made in natural gas resource exploration in the Ordos Basin, Tarim Basin, Songliao Basin, Sichuan Basin and production areas in the South China Sea. Among them, the Sichuan Basin has the most abundant unconventional natural gas resources, which are buried in the five major oil and gas regions of Chongqing, South Sichuan, Northwest Sichuan, Central Sichuan and Northeast Sichuan in the Sichuan-Chongqing region. The cumulative proven natural gas geological reserves are 172251×10 ⁸ m ³ . Among them, only the tertiary reserves (proved reserves, predicted reserves, and controlled reserves) of Yuanba Gas Field have reached 1.1 trillion cubic meters (11000×108m ³ ).

At present, the natural gas reservoirs discovered in my country are mainly low-permeability tight sandstone gas reservoirs, carbonate gas reservoirs, volcanic rock gas reservoirs and shale gas reservoirs and other unconventional gas reservoirs. Most of the unconventional natural gas reservoirs in my country generally have the structural characteristics of weak edge-bottom water or no edge-bottom water, and these types of gas reservoirs all adopt the depletion development mode to exploit natural gas. The effective evaluation of the stable production potential of each gas well in a gas reservoir is an important basis for the development and adjustment of gas reservoirs, an important guarantee for the continuous and stable production of gas reservoirs, and the basis for efficient development of gas reservoirs. At present, the evaluation of the stable production potential of gas wells under the depleted development mode of gas reservoirs mainly adopts the qualitative analysis of the stable production capacity of gas wells based on the production performance curve of gas wells. Therefore, it is very important to establish a quantitative evaluation method for the stable production potential of gas wells under the depleted development mode of gas reservoirs to provide technical support for the efficient development of gas reservoirs.

SUMMARY OF THE INVENTION

The invention mainly overcomes the deficiencies in the prior art, and proposes a method for evaluating the potential for stable production of single well exploitation under the gas reservoir development mode.

The technical solution provided by the present invention to solve the above-mentioned technical problems is: a method for evaluating the potential for stable production of single well exploitation in a gas reservoir development mode, comprising the following steps:

Step S10, obtaining the original formation pressure p _i , the cumulative production time t and the average daily production q _g of the single well in the target gas reservoir;

Step S20, performing well test interpretation on a single well, and obtaining the current formation pressure p _R according to the well test interpretation result;

Step S30, calculating the average annual formation pressure attenuation degree R _da according to the current formation pressure p _R and the original formation pressure p _i ;

Step S40, using the addition method to calculate the average daily output q _g to obtain the current cumulative output G _p ;

Step S50, obtaining the dynamic reserves G of the gas reservoir;

Step S60, calculating the average annual cumulative output degree _Ra according to the obtained dynamic reserves _G and the current cumulative production Gp;

Step S70, evaluating the stable production potential of the gas well according to the obtained average annual formation pressure attenuation degree R _da and average annual cumulative production degree _Ra ;

When R _da ≤ 10% and R _a ≤ 10%, the stable yield potential is evaluated as strong;

When 10%＜R _da ≤15%, 10%＜R _a ≤15%, the stable yield potential is evaluated as strong;

When 15%<R _da ≤30%, 15%<R _a <30%, the stable yield potential is evaluated as general;

When 30%＜R _da ≤50%, 30%≤R _a ≤40%, the stable yield potential is evaluated as poor;

When R _da > 50% and R _a > 40%, the stable yield potential was evaluated as poor.

A further technical solution is that the specific process of the step S20 is: use Saphir software to carry out well test interpretation for a single well, and obtain a well test logarithmic curve; and obtain the current formation pressure p _R by fitting the well test logarithmic curve. .

A further technical solution is that the calculation formula in the step S30 is:

In the formula: R _da is the average annual formation pressure attenuation degree; p _R is the current formation pressure; _pi is the original formation pressure; t is the cumulative production time.

A further technical solution is that the specific process of the step S50 is: using Topaze dynamic analysis software to perform a production decline dynamic analysis on a single well, and fitting to obtain a production decline fitting curve of a single well, and then performing the production decline fitting curve. The dynamic reserve G of the gas reservoir is obtained by the dynamic interpretation of declining production.

A further technical solution is that the calculation formula in the step S60 is as follows:

In the formula: G is the dynamic reserves of the gas reservoir; _Ra is the average annual cumulative production level; G _p is the current cumulative production; t is the cumulative production time.

The invention has the following beneficial effects: a scientific evaluation index of stable production is added, and after comprehensively considering factors such as formation and production performance, there is a quantitative and scientific guiding method on how to stabilize the production of the gas reservoir. With the help of quantitative and scientific judgment methods, it is helpful to evaluate the stable production capacity of each single well in a gas reservoir block that has been put into development, and then to evaluate the production capacity of the entire gas reservoir, providing a quantitative basis for the efficient development of gas reservoirs.

Description of drawings

Fig. 1 is X1 single well production dynamic curve in the embodiment;

Figure 2 is a double logarithmic curve diagram of well testing interpretation in Well X1;

Fig. 3 is the pie chart of wells X1-X24 in the embodiment;

Fig. 4 is the evaluation diagram of the gas well production stability potential.

Detailed ways

The present invention will be further described below with reference to the embodiments and accompanying drawings.

Example

A method for evaluating the potential for stable production of single well exploitation under a gas reservoir development mode of the present invention comprises the following steps:

(1) Obtain the field production data of Well X1 in the target gas reservoir, and collect the original formation pressure p _i = 29.3MPa and the average daily production of each single well in the gas reservoir from the production site q _g = 12.4 (10 ⁴ m ³ / d) and cumulative production time t=4.93 years;

(2) Through the on-site production performance curve of Well X1 (Fig. 1), the pressure recovery test data of Well X1 were obtained, including the reservoir porosity of Well X1 = 7.77%, the average thickness of the reservoir h = 16.3m, the single well leakage Flow radius r _w = 0.07m, pressure recovery time before shut-in t _p = 950h, wellhead flow rate q = 12.4×10 ⁴ m ³ /d, formation temperature T = 91.8°C, methane content of natural gas components 94.1%, ethane content 1%, propane content 0.7%, CO ₂ content 4.2%;

(3) Combine the existing data, and select Saphir software to carry out well test interpretation for Well X1;

(4) Double logarithmic curve of well test interpretation (Fig. 2); since the well type of Well X1 is a vertical well, and the gas reservoir produced is an isotropic gas reservoir, the pressure recovery well test interpretation model is selected, and then according to the selected model , and the relevant well test interpretation data done in the previous steps, use the well test interpretation software to conduct well test analysis, and obtain the current formation pressure p _R = 15.61MPa;

(5) Knowing the original formation pressure value p _i = 29.3MPa and the current formation pressure value p _R = 26.94MPa of Well X1, the current pressure depletion degree can be calculated by the following formula:

(6) And the cumulative production time (in years) of a single well is known, and the average annual (pressure) depletion degree of Well X1 is obtained and counted;

(7) The average daily production of Well X1 is q _g = 12.4 (10 ⁴ m ³ /d). Using the additive method, the current cumulative production of a single well is calculated to be G _p = 42.5×10 ⁴ ×4.93×365=7.6477×10 ⁸ m ³ ;

(8) Collect the pressure recovery test data of Well X1 from the production site, including the reservoir porosity of Well X1 = 7.77%, the average thickness of the reservoir h = 16.3 m, the single well discharge radius r _w = 0.07 m, the well shut-in Pre-pressure recovery time t _p = 950h, wellhead flow rate q = 42.5×10 ⁴ m ³ /d, formation temperature T = 91.8°C, and natural gas components methane content 94.1%, ethane content 1%, propane content 0.7%, CO ₂ content of 4.2%; using the above data, combined with Topaze dynamic analysis software, and adopting the Blasingame production decline analysis method, the production decline dynamic analysis of Well X1 was carried out;

(9) According to the field production data, combined with the dynamic analysis software, the fitting curve of single well production decline was obtained by fitting. The well type of Well X1 is a vertical well, and the exploited gas reservoir belongs to the homogeneous gas reservoir in all directions, and the dynamic interpretation model of production decline is selected. , the fitted curve is dynamically explained with decreasing yield;

(10) According to the selected model, adjust the parameters of Well X1. These parameters include the skin coefficient of Well X1, the average thickness of the controlled formation, the ratio of horizontal permeability to vertical permeability, and the parameters generate a theoretical curve to develop production decline dynamics. Interpret the curve fit;

泄气半径r_e＝1630m、动态储量G＝5.19×10⁸m³；(11) Output production dynamic analysis and interpretation results parameters, these parameters include the skin coefficient S=-0.12 of Well X1, the horizontal permeability kh = 2.8mD, the vertical permeability k _v = _0.224mD , the ratio of horizontal and vertical permeability

Deflation radius r _e =1630m, dynamic reserve G=5.19×10 ⁸ m ³ ;

(12) Obtain the current cumulative production G _p and dynamic reserves G of Well X1, and calculate the current cumulative recovery degree:

(13) And the cumulative production time (in years) of the current testing well X1 is known, the average annual cumulative production degree of a single well is obtained, and statistics are made;

(14) Finally, it was evaluated as strong according to R _da =9.37%<10% and R _a =8.71%<10%.

And obtain the data of wells X2-X24 respectively as table 1;

According to the above steps, the X2-X24 wells are evaluated, and the evaluation results are shown in Table 2;

According to the evaluation results, the total number of wells in each case is counted and represented by a pie chart (Fig. 3); different improvement suggestions are provided for gas wells with different potential capabilities. For gas wells with strong and strong stable production potential, keep the current working system stable; for gas wells with moderate stable production potential, appropriately increase the production pressure difference of the gas reservoir; for gas wells with poor and poor stable production potential, improve the current working system and reduce the number of wells The influence of the surrounding skin factors, and the artificial steam injection method was adopted to keep the formation pressure stable.

The above is not intended to limit the present invention in any form. Although the present invention has been disclosed through the above-mentioned embodiments, it is not intended to limit the present invention. Any person skilled in the art, within the scope of the technical solution of the present invention, When the technical contents disclosed above can be used to make some changes or modifications to equivalent embodiments with equivalent changes, any simple modifications or equivalents to the above embodiments according to the technical essence of the present invention do not depart from the content of the technical solution of the present invention. Changes and modifications still fall within the scope of the technical solutions of the present invention.

Claims (3)

1. a method for evaluating the potential for stable production of single well exploitation under a gas reservoir development mode, is characterized in that, comprises the following steps: Step S10, obtaining the original formation pressure p _i , the cumulative production time t and the average daily production q _g of the single well in the target gas reservoir; Step S20, performing well test interpretation on a single well, and obtaining the current formation pressure p _R according to the well test interpretation result; Step S30, calculating the average annual formation pressure attenuation degree R _da according to the current formation pressure p _R and the original formation pressure p _i ;

In the formula: R _da is the average annual formation pressure attenuation; p _R is the current formation pressure; _pi is the original formation pressure; t is the cumulative production time; Step S40, using the addition method to calculate the average daily output q _g to obtain the current cumulative output G _p ; Step S50, obtaining the dynamic reserves G of the gas reservoir; Step S60, calculating the average annual cumulative output degree _Ra according to the obtained dynamic reserves _G and the current cumulative production Gp;

In the formula: G is the dynamic reserves of the gas reservoir; _Ra is the average annual cumulative production level; G _p is the current cumulative production; t is the cumulative production time; Step S70, evaluating the stable production potential of the gas well according to the obtained average annual formation pressure attenuation degree R _da and average annual cumulative production degree _Ra ; When R _da ≤ 10% and R _a ≤ 10%, the stable yield potential is evaluated as strong; When 10%＜R _da ≤15%, 10%＜R _a ≤15%, the stable yield potential is evaluated as strong; When 15%<R _da ≤30%, 15%<R _a <30%, the stable yield potential is evaluated as general; When 30%＜R _da ≤50%, 30%≤R _a ≤40%, the stable yield potential is evaluated as poor; When R _da > 50% and R _a > 40%, the stable yield potential was evaluated as poor. 2. The method for evaluating the potential of single well exploitation and stable production under a gas reservoir development mode according to claim 1, wherein the specific process of the step S20 is: using Saphir software to carry out well test interpretation for the single well, and obtain the test results. Well logarithmic curve; and fitting the well test logarithmic curve to obtain the current formation pressure p _R . 3. The method for evaluating the potential of single well exploitation and stable production under a gas reservoir development mode according to claim 1, wherein the specific process of the step S50 is: utilize Topaze dynamic analysis software to carry out a dynamic analysis of production decline for a single well , and fit the production decline fitting curve of a single well, and then perform the production decline dynamic interpretation on the production decline fitting curve to obtain the dynamic reserves G of the gas reservoir.

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