Afterflow correction well test interpretation method of low-production horizontal well

Abstract

The invention discloses an afterflow correction well test interpretation method of a low-production horizontal well. The afterflow correction well test interpretation method comprises the following steps of firstly, according to the percolation characteristic of the horizontal well in an oil reservoir, constructing a three-dimensional source function well test model; then, utilizing a superposition principle to obtain a total dimensionless well bottom pressure function considering well shaft storage effect and surface effect and a Lapras space function of the dimensionless well bottom pressure function; utilizing a Stehfest method to inversion, so as to obtain a total dimensionless well bottom pressure solution; according to a relationship between a well body structure and a dynamic liquid level, solving a total afterflow rate; according to an afterflow process, deriving a function between the afterflow rate and time for equal-capacity change; by considering an equivalent flow rate of afterflow rate, converting the dimensionless well bottom pressure into well bottom pressure after afterflow correction; finally, fitting the well bottom pressure function with corrected afterflow and an actually measured value, and determining parameters of the oil reservoir according to the fitting results. The afterflow correction well test interpretation method has the advantages that the calculating is simplified, and the calculating quantity is small; well test interpretation of the low-production horizontal well is accurately realized.

Description

technical field [0001] The invention relates to a well test interpretation method, in particular to a low-yield horizontal well continuous flow correction well test interpretation method. Background technique [0002] For a long time, in the process of well test interpretation of low-production horizontal wells, the phenomenon that the skin interpretation results of contaminated wells are negative, that is, the interpretation results do not match the production understanding. Therefore, the reasonable analysis of the pressure recovery data of low-production horizontal wells, and the correction and interpretation of abnormal wells that cannot be reasonably explained by traditional methods are urgent well test analysis research topics to be solved. [0003] Based on a large number of technical investigations, in order to analyze the pressure recovery test data of low-production horizontal wells, the influence of bottomhole continuous flow has to be considered. The idea of ​​w...

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Problems solved by technology

[0006] However, in the actual analysis of low-yield horizontal well test data, the above-mentioned methods have been greatly restricted, and have not been widely promoted and applied. The main reasons are:

[0007] ① These methods are mainly researched on conventional test data, and cannot be well used to analyze test data of low-yield horizontal wells;

[0008] ②Due to a large number of convolution and deconvolution calculations, the data points of the corrected curve are discrete, resulting in permanent errors;

[0009] ③The accuracy and reliability are poor, the calculation is complicated, and the amount of calculation is large;

[0010] ④Although some of these methods are simple and easy to use, they have a low degree of correction for bottom-hole continuous flow;

[0011] ⑤ None of these methods can correct the additional pressure drop caused by the skin effect, especially when the skin is very large, most of the above methods have no obvious correction effect, and cannot obtain the corrected straight line segment, and most of the above methods cannot obtain the formation pressure ;

[0012] ⑥These methods all require directly measured flow data. However, in the actual test process, due to the limitation of the test process or test cost, only the pressure data is often measured, and the flow data is not measured at the same time.

[0013] Therefore, the use of test data of low-yield horizontal wells is greatly restricted, and almost none of the well-test interpretation software currently used at home and abroad includes the function of special processing for this part of the data, which cannot realize accurate well test interpretation of low-yield horizontal wells

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