电缆地层测试器预测试方法研究

Study on the identifying method of pretest in the formation test tool

文章分析了最新的电缆地层测试器中预测试的工作原理、预测室实现方式、预测室活塞运动方法,结合地层渗透性的大小选择相应的操作模式,从而获得最佳的测试结果,求出地层渗透率。常规预测试方法满足了早期传统仪器地层压力测试的需求;体积预测试比较适于渗透率较低的地层;限压力降预测试能够实现预测试过程中的流体流动压力大于地层饱和压力,避免发生汽化现象,所抽取流体为单相地层流体。在每种预测试模式选择中,预测试活塞的抽取速度还可以作为补充测试手段由操作工程师自己选定从而快速判断地层渗透性好坏。这些单独或组合预测试控制模式的应用使得电缆地层测试器的预测试功能适应性更强,渗透率估算更为准确。

This article focuses on the principle of pretest,the realization of pretest,and the movement of pretest piston.This article also explains how to choose the appropriate operation subsets according to the formation permeability.As a result,we can get the best test result and solve the formation permeability.The conventional pretest method can meet the need of traditional formation test demand.The volume pretest is more suitable for low permeability formations.The limited pressure pretest can make the flowing pressure higher than the formation saturation pressure during the test process,which avoids the gasification when the extracted liquid is in single phase.Adjusting the speed of pretest piston will become a supplemental way if an engineer wants to evaluate the formation permeability more quickly.The application of pretest subsets combination gets the functions of the cable formation pressure test more adaptable,and the permeability estimation more accurate.