酸对灰岩地层井壁稳定性及临界压差的影响研究  

EFFECTS OF ACID ON BOREHOLE FACE STABILITY AND CRITICAL PRODUCING PRESSURE DIFFERENCE IN LIMESTONE FORMATION

作　　者：刘向君[1] 徐晓雷[1] 刘洪[1] 孙万里[2] 戴岑璞[1] 韩林[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 [2]西南油气田分公司采气工程研究院

出　　处：《钻采工艺》2007年第4期112-115,共4页Drilling & Production Technology

基　　金：四川省青年学科带头人培养基金项目;编号:04ZQ026-051。

摘　　要：井壁稳定问题不仅直接影响着钻井的安全高效,而且影响着油气井完井方式的选取及油气田的开发效益。影响井壁稳定的因素包括力学的和物理化学的因素,涉及到油气田开发的全过程。为此,从岩石力学实验出发,以四川盆地某气藏飞仙关组灰岩储层为例,全面分析了盐酸作用前后灰岩地层岩石强度的变化规律,并基于实验结果,利用三维弹塑性有限元力学模型,计算分析了酸作用前后的井壁稳定性和临界生产压差的变化。研究表明,盐酸作用使岩石的机械强度及井眼的稳定性都有所降低;对致密砂岩、灰岩等在生产初期需进行酸洗、酸化或压裂增产措施的地层,其临界生产压差的控制应该考虑到增产措施的影响,而不应采用岩石的初始强度进行预测。另外,岩样取心方式对岩石强度参数、井壁稳定及临界压差的预测结果也有较大的影响。通过实验研究认为,岩石取心方式应视井眼在储层段的轨迹与水平向的夹角而定。对直井,岩石取心为直井全尺寸取心的侧向,对水平井,岩石取心则为直井全尺寸取心的平行方向。One of the most important factors affects directly safety and high efficiency of drilling is the borehole stability. It also affects the selection of well completion way and exploitation benefit of oil & gas field. The factors affecting borehole stability include mechanical and physical chemistry. It is related to all the work during oil & gas field development. Based on the rock mechanical experiments and taking Feixianguan limestone layers in one gas reservoir in Sichuan basin as an example, the rock intensity change law of limestone reservoir before and after hydrochloric acid working has been analyzed roundly. Then, based on the experiments results, using three-dimensional elastic-plastic finite element mechanical model calculated out the borehole stability and critical pressure differential. The result shows that hydrochloric acid makes mechanical intensity of limestone rocks and borehole stability reduce. The influence of stimulation must be considered in control of critical pressure differential for the competent sand and limestone reservoir, which is need stimulation before production like acid cleaning, acidizing and fracturing. The initial rock intensity must be not used in prediction. In addition, coring ways will affect the gain of rock intensity parameters, and the prediction of borehole stability and critical pressure differential. This study shows that coring ways must be decided by included angle between wellbore tracks in reservoirs and horizontal direction. For vertical well, coring direction will be the lateral of full dimension core from vertical wells; for horizontal well, coring direction will be the parallel.

关 键 词：井壁稳定 灰岩地层 酸作用 临界压差 有限元法 

分 类 号：TE21[石油与天然气工程—油气井工程]