Method for determining volume of well drilling cave

Abstract

A method for determining the volume of a well drilling cave comprises the steps that a wellbore storage coefficient is determined, specifically, the wellbore storage coefficient of a to-be-analyzed well is determined according to obtained dynamic well-testing data of the to-be-analyzed well; the total volume of fluid is determined, specifically, the wellbore of the to-be-analyzed well and the total volume of the fluid in the drilling cave are determined according to the wellbore storage coefficient of the to-be-analyzed well; and the volume of the cave is determined, specifically, the fluid volume in the wellbore of the to-be-analyzed well is obtained, and by combining the wellbore of the to-be-analyzed well and the total volume of the fluid in the drilling cave, the fluid volume in the drilling cave of the to-be-analyzed well is determined, so that the volume of the drilling cave of the to-be-analyzed well is obtained. According to the method for determining the volume of the well drilling cave, the defect that the cave volume or the longitudinal size is determined through a static method can be overcome, by utilizing a dynamic well-testing analysis method, the volume size of the well drilling cave can be accurately determined, and thus a more accurate evidence is provided for later development of a fracture-vug type carbonate-reservoir-rock cave reservoir body.

Description

technical field [0001] The invention relates to the technical field of oil and gas exploration and development, in particular to a method for determining the volume of karst caves encountered in well drilling. Background technique [0002] There are large karst caves in the reservoir space of fractured-cavity reservoirs. When wells encounter karst caves, venting and leakage will occur. The determination of the volume of karst caves can provide an important reference for later effective development. At present, the methods used to determine the volume of karst caves encountered by well drilling are mainly static methods, including seismic data interpretation methods and logging data analysis methods. [0003] However, for existing methods, since the current seismic accuracy is about 15m, and the size distribution of caves can range from a few meters to tens of meters, when the size of the cave is less than 15m, the volume of the cave cannot be determined by using seismic data...

AI Technical Summary

Problems solved by technology

[0003] However, for existing methods, since the current seismic accuracy is around 15m, and the size distribution of caves can range from a few meters to tens of meters, when the size of the cave is less than 15m, the volume of the cave cannot be determined by using seismic data

Furthermore, even if the size of the cave is larger than 15m, the size of the cave determined by seismic interpretation data will not be accurate enough

[0004] In addition, conventional logging or imaging logging can only judge the vertical size of the cave, but cannot determine the planar distribution of the cave, and it is difficult to determine the size of the cave volume

[0005] Therefore, it is difficult to accurately determine the size of the cave volume only by means of geophysics and well logging

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