一种含油气井钻井过程中地层压力计算方法  

A method to calculate the reservoir pressure during drilling

作　　者：叶长文 董钟骏 张琴 谢佳晨 袁浩 梅峻铭 陈雪松 郑学钢 YE Changwen;DONG Zhongjun;ZHANG Qin;XIE Jiachen;YUAN Hao;MEI Junming;CHEN Xuesong;ZHENG Xuegang(Chuanxi Drilling Company,CNPC Chuanqing Drilling Engineering Company Limited,Chengdu,Sichuan 610051,China;Chongqing Trans-portation Co.,Ltd.,CNPC Chuanqing Drilling Engineering Company Limited,Chongqing 401120,China)

机构地区：[1]中国石油川庆钻探工程有限公司川西钻探公司,四川成都610051 [2]中国石油川庆钻探工程有限公司重庆运输总公司,重庆401120

出　　处：《天然气技术与经济》2025年第2期32-36,共5页Natural Gas Technology and Economy

摘　　要：四川盆地中部地区油气显示活跃,纵向上分布多达31套油气层,但是由于受地层不整合的影响,地层压力预测极为困难。上部陆相地层经常遭遇突发的浅层气,特别是伴生着浅层含油的高压油气,压井计算和施工难度更大,现场往往因计算依据不充分导致溢流的处置陷入被动的局面。为了解决川中浅层高压油气(含油伴生气)溢流压井泥浆密度计算不准确的问题,结合PY2井采用往复式工程师法压井成功的案例,对含油气井压力构成及计算不准的现象进行了分析研究,采用了一种考虑油柱自锁力的新的地层压力计算方法,计算得到的压井泥浆密度与实际地层压力当量密度相符,可实现一次压井成功的目标。研究结果表明:①对传统压井公式计算压井液密度结果不准的原因进行分析,得出高压油气存在油柱自锁现象;②采用新的地层压力计算公式,计算得到的压井泥浆密度与实际压井密度偏差只有0.8%,提高了压井液密度的精准度,满足实际压井需求;③新公式计算出的地层压力更接近于实际地层压力,因此对于含油气溢流井采用新方法进行压井可以大大降低井控风险,减少生产损失。研究结论认为:该方法对处置类似的浅油气层溢流井极具参考价值,值得推广。Oil and gas show is active in central Sichuan Basin where is developed with more than 29 sets of hydrocarbon reservoirs vertically.However,stratigraphic unconformity results in great challenges in predicting reservoir pressure.Shallow gas may be often discovered unexpectedly in upper terrigenous strata,especially where is accompanied with some oil-bearing oil and gas with high pressure,creating difficulties in pressure calculation or well killing.In addition,insufficient calculation evidence may cause overflow failure.Thus,in order to precisely calculate the density of killing mud for overflow in such shallow oil and gas(oil-bearing accompanied gas)layers with high pressure in central basin,both pressure origin in such wells and the phenomenon of incorrect calculation were discussed through successful killing in PY2 well by means of the reciprocating engineer method.Then,taken oil column self-locking force into consideration,a new method to calculate the reservoir pressure was used to achieve the killing-mud density in accordant with the equivalent density of actual pressure,so that one-trip killing could be realized in success.Results show that(i)the reason why the improper density is computed by means of traditional killing formula is analyzed.And it is suggested there is the self-locking phenomenon in high-pressure oil and gas;(ii)the killing-mud density calculated from the new method has a deviation of only 8%from the actual density,indicating this accuracy is improved and can meet requirement of actual killing;and(iii)the calculated reservoir pressure is closer to the real pressure,implying this method can diminish well control risk greatly and reduce production loss.In conclusion,the method is of great referential value for disposing similar shallow oil and gas overflow wells.

关 键 词：浅油气层 溢流 压井 地层压力 钻井 

分 类 号：TE21[石油与天然气工程—油气井工程]