川东地区石炭系压力场分区及气水界面预测

PREDICTING PRESSURE FIELD DIVISIONS AND GAS-WATER INTERFACE OF CARBONIFEROUS IN EAST PART OF SICHUAN

川东地区石炭系水井的原始地层压力在不同地区甚至相同深度均有较大差别，造成川东大的区域无统一压力系统。通过大量钻井、试油及气水分析资料综合研究认为，川东石炭系存在３个不同的压力区。东、西两区各自有统一的压力系统，它们之间的压力差约３ＭＰａ；异常高压区主要分布在石炭系缺失区边缘，一般无统一的压力系统。在压力分区的基础上，还对同一压力系统内由于流体密度差所引起的压力变化进行了探讨，指出川东石炭系地层水存在密度差时，在高陡构造起伏较大的地区会造成压力的超压或损失。通过编绘石炭系气藏气水界面压力与海拔的关系图版，在仅有一口气井控制的情况下，能较准确地预测石炭系含气圈闭的气水界面，这对评价勘探决策有一定的参考价值。

The initial stratum pressure of Carboniferous water wells in the east part of Sichuan are very different in different areas. furthermore, those of the same depth are also very different, which leads to that non-unified pressure system appears in the big area of east Sichuan. It is considered that there are three different pressure areas in Carboniferous of east Sichuan by analysing a lot of data of drilling and potential test. There are respectively unifed pressure systems in the cast and west areas, and the pressure difference between them is about 3 MPa. Abnormal pressure areas mainly distribute on the border of non-Carboniferous, generally without unified pressure system The pressure change caused by fluid density contrast in the same pressure system is discuased on the base of pressure divisions.The superpressure or lost pressure is happend in the areas where high and steep structure undulates intensely when the formation water in Carboniferous of east Sichuan is of density contrast. Through compiling the reiation chart between the pressure of the gas-water interface and sea level elevation, the gas-water interface of Carboniferous gas-bearing strape can be precisely predicted in the condition only controlled by one gas well.