胜北构造硬脆性泥页岩裂隙特征及防塌机理

Frature Character and Collapse Mechanism of the Hard Brittle Mud Shale in Shengbei Structure

为了寻求吐哈油田胜北构造硬脆性泥页岩地层防塌措施，分析了其裂隙发育特征和坍塌机理，表明其综合水敏性属中～弱膨胀和中～弱分散，地层岩石具有典型硬脆碎特征，受山前构造运动产生的构造应力、蒙脱石在成岩脱水过程中产生的膨胀力以及厚薄不等的大段夹层煤的共同作用，形成了发育的裂隙和微裂缝，遇水（钻井液滤液）长时间浸泡易产生剥落掉块，引起周期性坍塌．采用提高钻井液的抑制性、改善钻井液的泥饼质量、封堵地层微裂缝的综合物理化学方法可以防治这类地层的井眼坍塌．

In order to seek the slughing prevention measures for the mud shale in Shengbei structure,the fracture character and the collapse mechanism of the mud shale are analyzed.The analysis shows that the mud shale can be classified into middleweak swelling and dispersion mud shale,its formation rock is hard and brittle,and there are develpoed fissure and microfracture in it.Cyclic collapse will take place when the mud shale is soaked in the filter liquor of drilling fluid for a long time under the joint effects of the structural stress produced by range-front tectonic movement,the expansion force produced by montmorillonite in the process of diagenism and dehydration,and coal interbeds with different thickness.The wellbore collapse of this type formation can by prevented by increasing drilling fluid inhibition,improving the quality of drilling fluid filter cake and plugging formation microfrature.