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应用声波测井和电阻率测井得来的资料,可以确定在页岩孔隙空间的流体压力。这个方法包括建立在页岩传播时间的或页岩电阻率的普通对数值与关于流体静压力地层的深度之间的关系。在传播时间对深度的图上,一般可以观察到线性关系,而在电阻率对深度的图上,存在非线性的趋势。观察到的传播时间或电阻率值,与在流体静压力条件下,从已建立的正常压紧作用趋势所得到的那些数值之间的分歧,是在页岩中孔隙流体压力的度量,并且,因之是在相邻的隔离的渗透性地层中孔隙流体压力的度量。这个关系已经由在相邻渗透性地层中实际压力测量经验地建立起来。这些资料和这个方法的应用,使得从声波测量和电阻率测量得到的流体压力的解释精度达到约0.04磅平方吋/呎,或约400磅平方吋/10000呎。电阻率法的标准偏差是0.022磅平方吋/呎,声波法的标准偏差是0.020磅平方吋/呎。关于在一个地质区域,首次发生超压(Overpressures)以及精确的压力-深度关系的这些知识,能够使钻井技术、套管设计、完井方法以及对储集层的估价诸方面得到改进。
Using sonic logs and resistivity logs, the fluid pressure in the shale pore space can be determined. This method includes establishing the relationship between ordinary logarithm of shale propagation time or shale resistivity and depth with respect to hydrostatic pressure strata. In the plot of propagation time vs. depth, a linear relationship can generally be observed, whereas in the plot of resistivity vs. depth, there is a non-linear tendency. The observed differences in propagation time or resistivity values from those obtained under the established hydrostatic pressure conditions from the established normal tendency of compaction action are a measure of pore fluid pressure in shale and, It is therefore a measure of pore fluid pressure in adjacent, isolated, permeable formations. This relationship has been empirically established by the actual pressure measurements in adjacent permeable formations. This information and the application of this method have enabled the interpretation of fluid pressure from sonic and resistivity measurements to be approximately 0.04 psi Sf / ft, or approximately 400 psi Sf / 10000 ft. The standard deviation of the resistivity method is 0.022 pounds square inches per square foot and the standard deviation of the sonic method is 0.020 pounds square inches per square foot. This knowledge of the first occurrence of overpressures and precise pressure-depth relationships in a geological area can improve aspects of drilling technology, casing design, completion methods, and reservoir valuation.