A Prediction Method of Pore Pressure in Non-undercompacted Formation

Abstract

The invention relates to a method for predicting the pore pressure of a non-undercompacted formation. Use on-site drilling to establish the intersection diagram of compressional wave velocity and density. According to the mudstone at different depths drilled on site, establish the intersection point of velocity and density of these mudstones in the intersection diagram of compressional wave velocity and density, and then merge the velocity and density that deviate from the loading trend line. The point and the classic pressure unloading model are compared to determine the cause of abnormal pressure in non-underpressure formations, and the formation velocity is used to calculate the mudstone pore pressure at different depths, and the pressure coefficient error between the statistically calculated mudstone pore pressure and the measured mudstone pore pressure , using the formation depth and pressure coefficient error to establish a fitting function, using the mudstone pore pressure obtained from the fitting function and the obtained mudstone pore pressure to realize the non-undercompacted formation pore pressure prediction. The beneficial effect of the present invention is to realize the prediction of the pore pressure of the non-under-compacted formation, and realize the qualitative judgment of the cause of the abnormal pressure of the non-under-compacted formation.

Description

Technical field [0001] The present invention relates to a method for predicting pore pressure in a non-undercomposited formation. Background [0002] The development of stratigraphic pore pressure prediction technology at home and abroad, including the 1970s to the 1980s, researcher Fillippone proposed the Fillione formula that does not rely on the trend of residual normal compaction rate, but uses stratigraphic velocity to predict pressure; researcher Bowers pointed out in 1995 that due to different pressurization and pressure evolution processes, the porosity of the formation will often not change with the formation pressure In 1998, researcher Djevanshir and researcher Akhnerdiev used the actual measured pressure of drilled wells to establish an empirical relationship, and revised the estimation results of the equivalent depth method, as well as proposed improved formulas according to the situation of their respective study areas; in 1990, domestic researchers found through t...

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Problems solved by technology

[0003] At this stage, many methods for predicting formation pore pressure have been proposed at home and abroad, but they are basically based on the traditional mudstone undercompaction model. The cause of pressure in non-undercompacted formations can only be analyzed qualitatively and cannot be calculated quantitatively. With the expansion of exploration fields and layers, the pore pressure prediction technology of under-compacted formations has been unable to predict formation pore pressures with high precision, which greatly restricts the progress of oil and gas exploration.

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