水平气井井壁稳定性研究  

STUDY ON WELLBORE STABILITY OF HORIZONTAL GAS WELLS

作　　者：周长江[1] 刘向君[1] 张卓[1] 刘洪[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：《天然气工业》2006年第8期81-82,89,共3页Natural Gas Industry

基　　金：四川省2004年青年学科带头人培养基金项目(编号:04ZQ026-051)资助

摘　　要：文章以均质各向同性和线—弹性模型为依据,在某气田地应力、岩石强度等参数研究的基础上,应用Mohr?Coulomb强度判别准则,就不同地应力环境、不同孔弹性系数以及压力衰竭对水平井井壁稳定性的影响进行了研究。结果表明,应力非均匀性越强,井壁越不稳定;孔弹性系数对井壁稳定性的影响也很明显,由于地应力和孔隙压力的作用在一定时期内是相对稳定的,而有效应力大小与孔弹性系数值有关,不同的孔弹性系数值会使有效应力的大小关系发生变化,从而可能使得井壁稳定性分析结果不同,甚至截然相反;随着地层压力的降低,作用在最大剪切应力平面上的剪切应力显著增加,井壁越容易发生剪切垮塌。因此,在气井井壁稳定性分析过程中,准确确定原地应力的大小、方向和慎重地选取孔弹性系数值以及考虑压力衰竭的影响具有重要意义。In this paper, according to the homogeneity and liner-elastic model, on the basis of study on in-situ stress and rock-strength of one gas field, using the Mohr-Coulomb rock-failure criterion, the wellbore-stability is analyzed under different in-situ stress environment, different Biots factor and with the influence of pressure depletion. The results suggest that 1) the more heterogeneous the in-situ stress, the worse the wellbore stability is; 2) the Biots factor affects the wellbore-stability obviously, because the effects of in-situ stress and pore pressure are relatively stable in a given time, while the effective stress is related to Biots factor, which may lead to different analysis results regarding wellbore stability; 3) the wellbore is easier to collapse when the pore pressure is dropping, because that will largely increase the maximal shear stress. To conclude, it is important for wellbore stability study for gas wells to determine the in-situ stress precisely, to choose the Biots factor carefully and to be aware of the effects of pore pressure dropping.

关 键 词：气田 水平井 井壁稳定 地应力环境 孔弹性系数 压力衰竭 

分 类 号：TE21[石油与天然气工程—油气井工程] TE375