新场构造三压力剖面计算方法  

TTHREE PRESSURE PROFILE COMPUTING METHOD OF XINCHANG TECTONICS

作　　者：刘其明[1] 黄建智[2] 卢蜀秀 

机构地区：[1]中国石化西南油气分公司工程技术研究院 [2]青海油田井下作业公司 [3]长庆油田公司气田开发处

出　　处：《钻采工艺》2011年第5期37-40,7,共4页Drilling & Production Technology

基　　金：中国石化科技项目(编号:GJ-105-0817)的部分研究成果

摘　　要：新场构造地层岩石致密、硬度大、可钻性差,机械钻速低,欠平衡钻井能有效地提高机械钻速,由于该地区地层压力高、泥页岩发育稳定性差,有必要开展欠平衡钻井适应性研究,建立地层三压力剖面,优选适合欠平衡钻井地层及确定合理的欠压值,为工程施工优化设计提供科学依据。在分析欠压实理论的基础上,运用伊顿法利用测井资料,结合实测资料建立了新场构造钻遇地层准确的孔隙压力剖面;通过井壁力学理论分析,结合实钻井资料,确定了井眼扩大率为60%是新场构造允许井眼最大垮塌范围,然后计算出井眼扩大60%时地层坍塌压力;根据岩石最大拉应力理论,结合钻井试压和储层水力压裂资料,建立了较准确的地层破裂压力剖面。三压力剖面计算结果表明,新场地区地层破裂压力比孔隙压力和坍塌压力高,差值较大,具有较宽的泥浆窗口;须二以上地层坍塌压力与孔隙压力之差相对较大,适合液体欠平衡钻井,欠压值在0.3g/cm3左右,须二地层孔隙压力与坍塌压力接近,不适合液体欠平衡钻井;同时须二段地层孔隙压力与上部须三段地层坍塌压力一致,目前以须二段为目的层的常规钻井四开次钻井身结构可以进一步优化,简化井身结构,加快建井周期。The formation of Xinchang tectonics have poor drillability and low ROP for dense and hard rocks,and the underbanlanced drilling can efficiently enhance penetration rate. Because of high formation pressure and poor stability of clay shale in this area,it is necessary to research the adaptability of the underbalanced drilling,establish the formation three pressure profile,select the formation suited for underbalanced drilling and determine reasonable underpressured values in order to provide scientific basis for drilling design optimization. Based on the undercompaction theory,accurately pore pressure of the drilled formation could be gained by Eaton method and logging data;Through theoretical analysis of wellbore mechanics and real drilling data,maximal wellbore collapse permissibility range of Xinchang formation was figured out as 60% of wellbore expansion rate,and the caving pressure was computed when the wellbore expansion rate reached 60%;According to the maximum tensile stress theory of rock,and drilling pressure and reservoir hydraulic fracturing data,accurate formation fracture pressure profile has been established. Three pressure profile calculation results showed:In Xinchang area,the fracturing pressure was higher than pore pressure and collapse pressure with large difference,having wide mud windows;If the difference between the Xujiahe 2 formation collapse pressure and pore pressure was relatively large,the liquid underbalanced drilling with underpressured values of 0.3g/cm3 was suitable;if the Xujiahe 2 formation collapse pressure was close to pore pressure,the liquid underbalanced drilling was not suitable. At the same time,if the Xujiahe 2 formation pore pressure was equal to Xujiahe 3 formation collapse pressure,the fourth casing programme of conventional drilling with target zone of Xujiahe 2 could be optimized.

关 键 词：新场构造 液体欠平衡 孔隙压力 坍塌压力 

分 类 号：TE21[石油与天然气工程—油气井工程]