侧钻分支井分叉段井壁稳定分析

Wellbore Stability of Juncture of Multilateral Drilling Well

老井侧钻可有效开发老井未受控面积内的储油和死角残油并有效提高产能。而分支井眼连接井段的稳定性是成功完井的关键。采用三维有限元方法对侧钻短半径水平井井壁稳定进行弹塑性分析。分析结果表明:侧钻井眼在与主井眼连接处存在应力集中,容易发生井壁失稳。随井间距的增加两井眼中间单元应力逐渐减小,两者互相影响减小。两井眼间距为主井眼尺寸的2倍时,两井眼之间的影响可以忽略。适当的增加造斜率,让侧钻井眼快速的脱离主井眼,可以降低连接段的长度,降低井壁失稳的风险。适当增加泥浆密度,可以降低连接井段井壁失稳的风险。

Thought the sidetrack drilling well can adequately exploit the oil than can be control by the old well. And the stability of the junction of lateral well and main well is the key of completion well. By the three-dimensional FEA elastic-plasticity analyze the short radius lateral drilling well. The result shows the juncture of side well and main well occur stress concentration, wellbore instability. With wellbore distance reducing, the interference of well reduces; when the distance is the two times the main well diameter, the interference can be ignored. Properly increase the build-up rate make the side well fast leave the main well can reduce the risk of instability. Properly increase drilling fluid density can reduce the risk of instability.