Method for determining pressure coefficient and drilling mud density of carbonate rock fracture-cavity type oil and gas reservoir

Abstract

The invention provides a method for determining a pressure coefficient and drilling mud density of a carbonate rock fracture-cavity type oil and gas reservoir. The method comprises the steps of obtaining the original formation pressure of a fracture-cavity type reservoir development horizon of a target area; determining the fracture-cave body volume of the fracture-cave type reservoir developmentlayer of the target area; obtaining the mud leakage amount and stratum fluid parameters in the drilling process of the fracture-cavity type reservoir development horizon of the target area; based on the original formation pressure, the fracture-cave body volume, the mud leakage amount and the formation fluid parameters, determining the formation pressure after mud leakage in the drilling process through a material balance equation; and determining the true formation pressure coefficient of the fracture-cavity type reservoir development layer of the target area based on the determined formationpressure after mud leakage.

Description

technical field [0001] The invention relates to the technical field of oil and gas exploration, in particular to a method and device for determining the pressure coefficient and drilling mud density of carbonate rock fracture-cavity oil and gas reservoirs. Background technique [0002] Fracture-vuggy carbonate reservoirs are often dominated by atmospheric pressure, and there are often phenomena such as lost circulation, prevention and control, and faster drilling during the drilling process, which bring certain risks to safe drilling and lead to the exploration of carbonate reservoirs. Difficulty tends to be greater than that of clastic rock. In recent years, with the advancement of oil and gas exploration in fractured-vuggy carbonate rocks in deep and ultra-deep ancient formations, ultra-high pressure phenomena have been newly discovered, and the pressure coefficient of some fractured-vuggy well intervals exceeds 1.7, which has brought great harm to safe drilling. Huge cha...

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Problems solved by technology

[0002] Fracture-vuggy carbonate reservoirs are often dominated by atmospheric pressure, and there are often phenomena such as lost circulation, prevention and control, and faster drilling during the drilling process, which bring certain risks to safe drilling and lead to the exploration of carbonate reservoirs. Often more difficult than clastic rock

In recent years, with the advancement of oil and gas exploration in fractured-vuggy carbonate rocks in deep and ultra-deep ancient formations, ultra-high pressure phenomena have been newly discovered, and the pressure coefficient of some fractured-vuggy well intervals exceeds 1.7, which has brought great harm to safe drilling. Huge challenges, blowouts, overflows, etc. often occur; the density of drilling mud is also increasing, which brings difficulties to oil and gas discovery; well control safety and drilling costs have become major problems in the exploration and development of fractured-cavity carbonate reservoirs

[0003] Therefore, it is necessary to develop a new method for calculating the pressure coefficient of fractured-cavity reservoirs. Before drilling, the pressure coefficient of the target layer and the distribution of abnormal pressure can be known, and the well control safety risk and drilling pressure caused by abnormal pressure can be effectively solved. To solve the problem of high cost, realize the safe and rapid exploration and development of carbonate fracture-cavity reservoirs in deep ancient formations, solve the disadvantages that the pressure coefficient cannot be accurately predicted in advance, and provide new technical support for the efficient exploration and development of fracture-cavity reservoirs

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