随钻电阻率受地层各向异性影响的判别

The method of recognizing aeolotropy influence and inversing for logging while drilling resistivity

随钻测井已经成为大斜度井、水平井和小井眼的侧钻多分支井油气藏评价的重要手段,是定向井的关键技术之一。在大斜度井和水平井中随钻电阻率受地层倾角、井斜角的影响比较大,常规各向异性校正处理中,一般针对服务公司提供的校正图版来做手工校正,但基于图版的各向异性校正方法中的各向异性系数较难确定,不利于逐点解释。为此,在考虑到各向异性图版校正数量少、并非完全符合实际地层情况的基础上,应用一种迭代算法来对随钻电阻率受地展各向异性影响进行反演校正。利用该方法对东部X1和X2等井进行了反演校正处理,结果表明该方法能较真实地反映实际地层电阻率。

Logging While Drilling(LWD) has become an important means of reservoir evaluation in highly deviated wells,horizontal wells and slim hole sidetracking multilateral wells and is one of the key technologies for the directional wells.Log response data cannot accurately reflect the logging while drilling resistivity owing to the effect of strata dip and deviation angle in highly deviated wells and horizontal wells.The conventional anisotropic correction based on handwork was carried out according to the correction chart which the service company provided,but the anisotropy coefficient is very difficult to be determined by the anisotropic charts,and goes against the level-by-level interpretation.Therefore,in consideration of the limited number of anisotropic charts and the inadequate outcomes,a method of recognizing aeolotropy influence and inversing for logging while drilling resistivity is proposed in this paper.At last,inverse corrections have been carried out for the logging data deduced from the eastern wells such as X1 and X2,and the results indicate that this inverse modeling can actually reflect the true formation resistivity.