摘要
深水油气是全球重要的战略接替资源,但深水勘探开发面临较大的井壁失稳问题,主要表现为安全密度窗口狭窄。研究过程中,针对非目的层与目的层成压机理不同,分别建立孔隙压力计算模型;针对深水浅部和深部(1/2水深为界限)地层的力学性质不同,分别建立了坍塌压力、破裂压力计算模型。在允许深水浅部出现1.8倍井眼面积塑性区的情况下,以水平最小地应力作为浅层破裂压力,二者结合确定深水浅层的安全压力窗口。针对深部地层,由于油气生烃作用引起的异常高压使得孔隙压力在几十米范围内迅速抬升,但破裂压力抬升缓慢,总体上深部地层,尤其是接近目的层的地带呈现出窄窗口的特点,需优化技术套管下深及目的层钻井液密度实现井眼稳定。最终,方法应用于南海某深水区域的探井实际作业过程,验证了方法可靠性。
Deepwater oil and gas is an important strategic replacement resource in the world,but deepwater exploration and development faces a large problem of wellbore instability,mainly manifested in the narrow window of safety density.In the research process,the pore pressure calculation models are established according to the different pressure forming mechanism between non target layer and target layer;For deep water,shallow and deep(1/2 water depth is the limit)the mechanical properties of the formation are different,and the calculation models of collapse pressure and fracture pressure are established respectively.Under the condition that the plastic zone of 1.8 times the borehole area is allowed to appear in the shallow part of deep water,the horizontal minimum in-situ stress is taken as the shallow fracture pressure,and the two are combined to determine the safety pressure window of deep water and shallow layer.For the deep formation,the abnormal high pressure caused by oil and gas hydrocarbon generation The pore pressure rises rapidly within tens of meters,but the fracture pressure rises slowly.Generally,the deep formation,especially the zone close to the target layer,presents the characteristics of narrow window.It is necessary to optimize the technical casing running depth and the drilling fluid density of the target layer to achieve borehole stability.This method is applied to the actual operation process of an exploration well in the South China Sea to verify the reliability of the method.
作者
饶志华
袁俊亮
幸雪松
范梓伊
Rao Zhihua;Yuan Junliang;Xing Xuesong;Fan Ziyi(Shenzhen Branch,CNOOC China Limited,Shenzhen Guangzhou 518000,China;CNOOC Research Institute Co.,Ltd,Beijing 100028,China;Zhejiang University of Technology,Hangzhou 310014,China)
出处
《科技通报》
2022年第10期96-100,共5页
Bulletin of Science and Technology
关键词
深水钻井
井壁稳定
孔隙压力
坍塌压力
破裂压力
deep-water drilling
well-bore stability
pore pressure
collapse pressure
fracture pressure
