地层声波时差的Faust改进算法及应用

Faust Improved Algorithm for Formation Acoustic Time Difference and Its Application

随钻声波时差测井数据为随钻地层孔隙压力监测计算的常用数据,但在钻井现场地层孔隙压力监测过程中,经常会因为工程原因导致随钻声波时差数据不可测得或地层原因中途缺失,常利用Faust公式对声波时差进行拟合,实践表明拟合声波时差与实测声波时差相对误差在5%以上。因此,文章将传统Faust公式进行改进,移除传统Faust公式中的垂深参数,并更改公式形式。经海上钻井实践得出:使用改进公式拟合计算的声波时差数据与实测声波数据相对误差能控制在5%以内,进而利用拟合声波时差计算的地层压力符合率在96%以上,可满足现场作业需求,且该式可同时用于随钻工具测井数据和电缆工具测井数据中。

LWD logging data are commonly used in formation pore pressure monitoring and calculation.However,in the process of formation pore pressure monitoring,LWD data are often undetectable due to engineering reasons or missing due to formation reasons.Therefore,Faust formula is often used to fit the LWD.Practice shows that the relative error between the fitted acoustic time difference and the measured acoustic time difference is more than 5%.Therefore,this paper improved the traditional Faust formula by removing the vertical depth parameter in the traditional Faust formula and changing the formula.The offshore drilling practice concluded that the relative error between the acoustic time data calculated by the improved formula fitting calculation and the measured acoustic data can be controlled within 5%,and the formation pressure coincidence rate calculated with the fitting of acoustic time is of over 97%,which can meet the demand of field operation,and this formula can be also used for LWD tool logs and wireline tool logs.