Analysis Of Pore Pressure In Qaidam Basin

Qaidam basin is located in the northern of Qinghai-Tibet Plateau, rich in oil and gas resources. However, there exists thick sedimentary strata, anisotropic stress and multiple sets of pressure systems, meanwhile, a number of tectonic movement makes the formation crushing, easy to collapse, loss, drilling complex are inevitable, these above reasons are serious constraints the exploratipon and development of oil and gas in The Qaidam Basin.Therefore, it is very important to analyze the three pressure of formation in the key area of Qaidam Basin, and it is meaningful to summarize the distribution characteristics of three formation pressure, and combine the actual drilling conditions to research the reasons of abnormal high pressure in formation.This paper sets out the database from the drilling data of drilling wells in key areas of Qaidam Basin. Through the statistical analysis of the complex situation, bit use, logging lithology data and geological structure background data in the drilling wells, the formation of pore pressure in the region has been made a preliminary analysis.By using log and well logging data, the pore pressure detection profile of drilled wells has been established. Through analyzing the drilling wells with complicated drilling technology in recent years, the main reasons for the complicated situation are found out. The pressure distribution of the stratum and the vertical contrast map of the well are drawn, and the characteristics of the formation pressure plane and the vertical distribution are found out.According to the geological structure features and actual drilling conditions of the Qaidam Basin, combined with logging data and seismic prediction results, we find out the abnormal pressure (abnormal low pressure and abnormal high pressure) developmental zones and intervals in the basin and the mechanisms of them, the results of the formation pressure calculation are checked according to the overpressure mechanism in the same time.