泥煤互层段井壁稳定分析新方法  

NEW METHOD FOR BOREHOLE STABILITY ANALYSIS OF ALTERNATING LAYER OF SHALE AND COAL

作　　者：严俊涛[1] 孟英峰[1] 李皋[1] 刘厚彬[1] 杨谋[1] 汪传磊[1] 

机构地区：[1]油气藏地质及开发工程国家重点实验室.西南石油大学

出　　处：《钻采工艺》2012年第4期19-21,122,共3页Drilling & Production Technology

基　　金：国家自然基金重点项目"气体钻井基础理论研究"资助;编号:51134004

摘　　要：井壁稳定是泥煤互层段地层安全钻进的一大难题。常规计算模型没有考虑不等厚煤层与泥页岩失稳时的相互影响,获得坍塌密度低于实际钻井工况条件下,容易造成局部不稳定地层失稳引起井壁大面积垮塌。文章通过岩石理化性能与力学实验,系统分析煤层及互层面的失稳机理,结合不稳定地层非连续性,建立了考虑泥煤互层影响的井壁坍塌压力计算模型,获得互层段坍塌压力随岩性变化的规律。计算结果表明互层段在考虑不同地层失稳影响后地层坍塌压力更大。该评价方法应用于吐哈油田泥煤互层段井壁稳定分析,理论计算与实际工况吻合程度高,为钻遇类似井段井壁稳定准确分析奠定了重要的基础理论。Borehole stability is the main problem of safety drilling in alternating layer of shale and coal.The conventional calculation model does not consider the mutual influence between variable thickness coal seam and shale layer,which causes wall caving that results from regional unstable formation when obtained collapse density was lower than actual condition.By experiment of physiochemical properties and mechanics of rock,the instability mechanics of coal bed and interbedding face were analyzed systematically,and based on the discontinuity of unstable formation,a collapse pressure calculation model considering interbedding influence was established to find the law of interbedding collapse pressure varying with the lithology.The calculation results showed that collapse pressure considering interbedding influence was higher.This evaluating method was applied for stability analysis of alternating layer of shale and coal in Tuba oilfield,moreover,the theoretical calculation highly coincided with the actual situation.

关 键 词：泥煤互层 不等厚煤层 井壁失稳 坍塌压力 

分 类 号：TE21[石油与天然气工程—油气井工程]