埕海油田二区沙河街组异常地层孔隙压力计算

CALCULATION OF THE ABNORMAL FORMATION PORE PRESSURE IN SHAHEJIE FORMATION OF BLOCK 2 IN CHENGHAI OILFIELD

埕海油田二区构造复杂，断层发育，其东营组以上地层属于正常压力系统，而沙河街组压力系数大于1．20为异常高压层。本文从等效深度法的基本原理出发，讨论了基于测井资料的砂泥岩地层正常压实趋势线的构建问题，并利用声波时差值建立了工区地层正常压实趋势线及方程，由此预测了沙河街组的地层孔隙压力，其预测值与实测值误差较小，与实钻显示情况吻合。结果表明，只要建立合理的正常压实趋势线方程，采用等效深度法可以较好地解决沙河街组异常地层孔隙压力的预测问题。

The structure of Block 2 in Chenghai oilfield is complex because faults develop well.The formation above Dongying group belongs to nor- mal pressure system while the pressure coefficient of Shahejie group is more than 1.20,belonging to abnormally high pressure.From the fundamental principle of equivalent depth method,construction of a normal compaction trend line for sand slime is discussed in the paper on the basis of logging data.The normal compaction trend line and equation of the work area are established through acoustic differential time values with which formation pore pressure of Shahejie group can be predicted.There is small error between predicted value and mea- sured value.It fits to the practical drilling condition.The result shows that the abnormal formation pore pressure in Shahejie group can be predicted with the equivalent depth method as long as a reasonable normal compaction trend line equation is established.