溢流环空压力峰值确定套管下深方法

Determination of casing setting depth based on peak overflow annulus pressure

霍宏博 许杰 谢涛 李金蔓 幸雪松 林海

HUO Hongbo XU Jie XIE Tao LI Jinman XING Xuesong LIN Hai

中海石油(中国)有限公司天津分公司 海洋石油高效开发国家重点实验室

CNOOC Tianjin Branch Company, Tianjin 300452, China State Key Laboratory of Offshore Oil Exploitation, Tianjin 300459, China

目前套管下深设计主要考虑关井压力，但实际压井过程中，循环排气时的环空压力峰值高于关井时的环空压力。为保证溢流井控全过程不压漏地层以及减少地层压力不确定性对井控风险的影响，通过计算循环压井将溢流物循环排出井筒过程中环空压力变化，计算出环空压力峰值，建立其随溢流强度变化的图版，并提出根据溢流环空压力峰值对比地层破裂压力确定套管下入深度的方法。结合油田实例计算证明：该方法能够明确套管下深可应对的井涌强度，使地层压力不确定性可控，实现了套管下深精细设计。

At present, shut-in pressure is the main factor that is taken into consideration when the casing setting depth is designed.In the actual process of well killing, however, the peak annulus pressure during the circulating out of the gas is higher than the annulus pressure during well shut-in. To prevent circulation loss in the whole process of overflow well control and reduce the effect of formation pressure uncertainty on well control risk, the peak annulus pressure was calculated by calculating the change of annulus pressure during the circulating of the overflow materials out of the borehole by means of circulative well killing, and the chart for the variation of peak annulus pressure with the overflow strength was established. Besides, it was proposed to determine the casing setting depth according to the peak overflow annulus pressure, combined with the formation fracture pressure. It is proved from the case calculation of an oilfield that this method can define the kick strength corresponding to the casing setting depth, and thus the uncertainty of formation pressure is the controllable and the casing setting depth is designed precisely.

10.13639/j.odpt.2017.06.005