Method for analyzing high-temperature and high-pressure reservoir pore pressure

Abstract

The invention relates to a method for analyzing the high-temperature and high-pressure reservoir pore pressure. The method comprises the following steps that relevant geologic and tectonic data and logging data of a target area are selected; mud rock formation sections of the target area are selected; the overburden pressure equal yield density of the whole well section is calculated; the sound wave-density trend point under different well depth conditions is obtained; an improved sound wave-density cross plot is obtained; pressure forming mechanism analysis of the abnormal formation pore pressure of the target area is conducted, and the contribution values of the different pressure forming mechanisms to the mud rock formation pore pressure of the target area are calculated; calculating methods of the mud rock formation pore pressure of the different pressure forming mechanisms are selected, and the mud rock formation pore pressure of the target area under the different pressure forming mechanisms is calculated; the actual mud rock formation pore pressure of the target area is calculated; if the sand stone formation thickness in the target area is no more than 15 m or the formationfluctuation falling head is no more than 50 m, the sand stone formation pore pressure is equal to the adjacent mud rock formation pore pressure; and otherwise, the sand stone formation pore pressureis calculated after the buoyancy effect is considered.

Description

technical field [0001] The invention belongs to the technical field of borehole wall stability in oil and gas well sandstone mudstone high-temperature and high-pressure formation drilling, and in particular relates to a high-temperature and high-pressure reservoir pore pressure analysis method. Background technique [0002] Formation pore pressure is the pressure of fluid (oil, gas, water) in rock pores, also known as pore pressure or formation pressure. The normal formation pore pressure is equal to the hydrostatic pressure of the continuous formation water from the surface to somewhere underground, which is called hydrostatic pressure; the formation pore pressure above and below the hydrostatic pressure are called abnormally low pressure and abnormally high pressure, respectively. Formation pore pressure is one of the basic parameters for drilling and completion engineering and oil and gas development. Accurate calculation of formation pore pressure in drilling engineering...

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Problems solved by technology

This set of formation pore pressure prediction methods mainly has the following problems: (1) There are too many subjective factors in the method of judging the formation mechanism of abnormal high pressure by using the acoustic wave-density crossplot of mudstone formation, and it is impossible to predict the formation of abnormal high pressure at a specific depth. (2) This method mainly predicts the formation pore pressure for a single abnormally high pressure mechanism. For the abnormally high pressure of multiple mechanisms, the error of the formation pore pressure calculated by this method is relatively large; (3) For The sandstone formation, especially the sandstone reservoir section, does not consider the centroid effect brought about by formation undulation and reservoir thickness, that is, the buoyancy effect caused by the difference in oil and gas density on the formation pore pressure

[0004] To sum up, in the case of complex geological and structural conditions, the formation pore pressure results obtained by the traditional formation pore pressure analysis method can hardly reflect the real situation of the formation pore pressure in the actual formation, and the calculated formation pore pressure will be used for subsequent drilling. design has an impact

With the transfer of oil and gas exploration to areas with complex geological conditions, the traditional formation pore pressure prediction methods can no longer meet the requirements of formation pore pressure prediction in such areas due to the diverse pressure formation mechanisms, special formation properties, and complex sedimentary and structural histories. Accuracy requirements

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