Method of Determining Volume Size of Karst-vug System Encountered by Gas Well Drilling Using Production Performance Data

Abstract

The invention discloses a method for determining the volume size of a gas well drilled into a karst cave system by using production dynamic data, including: based on the logging response characteristics and whether lost circulation occurs during drilling, preliminarily judging whether the production gas well has encountered a karst cave; based on the logging response characteristics Display the gas wells drilled with karst caves, collect and organize their production dynamic data; judge whether the karst caves encountered by the gas wells are connected to large-scale karst cave systems based on the production dynamic data at the initial stage of gas well production; The linear relationship between the apparent pressure and the cumulative gas production calculated by data and geological data can be used to quantitatively calculate the volume of the gas well connected karst cave system, and provide a quantitative reference for understanding the development degree of karst karstification in gas reservoirs.

Description

technical field [0001] The invention relates to the technical field of dynamic monitoring of gas reservoir development, in particular to a method for determining the volume of a gas well drilling encountered karst cave system by using production dynamic data. Background technique [0002] Cave systems are usually developed in carbonate strata that have been subjected to karst karstification during geological history. For wells that encounter karst caves, lost circulation generally occurs during the drilling process. Conventional logging and imaging logging can determine the size of the karst cave along the one-dimensional direction of the well trajectory, but it is difficult to determine the development of the karst cave system in the three-dimensional space. size and volume. [0003] At present, there are mainly two types of methods for determining the range or volume of the cave system in underground oil and gas reservoirs: one is to invert and predict the development ran...

AI Technical Summary

Problems solved by technology

For wells that encounter karst caves, lost circulation generally occurs during the drilling process. Conventional logging and imaging logging can determine the size of the karst cave along the one-dimensional direction of the well trajectory, but it is difficult to determine the development of the karst cave system in the three-dimensional space. Size and volume

[0003] At present, there are mainly two types of methods for determining the range or volume of the cave system in underground oil and gas reservoirs: one is to invert and predict the development range of the cave system by combining seismic and logging information, and the results obtained by this method are affected by the cavern system. Influenced by the uncertainty of the filling type and filling degree in the system, the prediction error of the volume of the effective storage space in the karst cave system is relatively large; the other type is the well test interpretation method, which is based on the geological understanding of the reservoir characteristics of the oil and gas reservoir , establish a corresponding theoretical model or numerical simulation model and solve it, match it with the actual well test data, and give the interpretation result of the size of the cave. The application of this type of method is relatively complicated, and there are multiple solutions

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