页岩水化对其力学性质和井壁稳定性的影响

MPACT OF SHALE HYDRATION ON ITS MECHANICAL PROPERTY AND BOREHOLE WALL STABILITY

罗健生 鄢捷年

Luo Jiansheng Yan Jienian

石油大学·北京

在对新疆油田呼图壁地区防塌钻井液配方进行优选的基础上,进一步研究了钻井液引起的水化与泥页岩力学性质和井壁稳定性的关系。试验和计算结果表明,泥页岩水化后由于抗压强度降低,粘聚力下降,因而对钻井液安全密度窗口有显著的影响。以呼002井泥页岩为例,水化后坍塌压力所对应的钻井液密度值提高了0.23g/cm3,破裂压力所对应的钻井液密度值降低了0.15g/cm3。在相同的试验条件下,泥页岩水化程度与钻井液类型有关。在所使用的3种防塌钻井液中,KCI两性离子聚磺钻井液对泥页岩的抑制作用为最好.

On the basis of optimization of antisloughing drilling fluids in Hutubi area of Xinjiang oil field, the relation between shale mechanical property and borehole wall stability and hydration caused by drilling fluid is further investigated. The result of test and calculation showed that the hydrated shale has a reduced compression strength and poor adhesive power, resulting in a significant impact on the safety window of drilling fluid density. For instance, in well Hu 002, the sloughing pressure of hydrated shale corresponded to an increase of 0.23g/cm3 in drilling fluid density and the fracture pressure corresponded to a decrease of 0.15g/cm3 in drilling fluid density. Under similar test condition, hydration of shale depends on the type of drilling fluid. In 3 type of anti——sloughing drilling fluid used in the test, the KCI amphoteric polysulfonate drilling fluid exhibits the best shale inhibiting effect.

10.3969/j.issn.1000-7393.1999.02.002