低渗透薄层碳酸盐岩气藏水平井地质导向技术

GEO-STEERING TECHNOLOGY FOR HORIZONTAL WELLS IN LOW-PERMEABILITY AND THIN CARBONATE GAS RESERVOIR

靖边气田下古生界马五1+2气藏具有典型的低渗、低孔特征,主力储层马五13厚度薄、横向非均质性强,且小幅度构造变化快。水平井地质导向面临小层判识难、地层倾角预测难、气层追踪难、控制轨迹难等"四难"问题。综合运用现场录井、钻井资料,根据目的层上下部地层接触关系,确定了5处靶点调整时机,4种入靶地层对比方法,3种水平段轨迹控制方法,保证了薄储层水平井精确入靶,提高了水平井有效储层钻遇率。

Lower Paleozoic Ma 51+2 gas reservoir in Jingbian gasfield is characterized by low permeability and porosity.Its main reservoir,Ma513,is featured by thin thickness,strong lateral heterogeneity and fast changes in low-amplitude structure.There are four difficulties occurring in geo-steering of horizontal well,including thin-layer identifying,formation-dip predicting,gas-zone tracing and trajectory control.Based on mud-logging and drilling data,according to the contact relation between upper and lower layers of target bed,this paper determines the timing of adjustment for five targets,four comparison methods for target-entering bed,and three methods for trajectory control of horizontal section.These may guarantee the target-entering accuracy and raise the drilling-encountering ratio of effective reservoir.