固化承压堵漏剂在渤海油田断层破碎带的应用

Application of Pressure-bearing Solidifying LCM for Mud Loss Control in Fault Zones in Bohai Oilfield

渤海油田地层完整性差,断层破碎带井漏等裂隙性漏失是困扰钻井工程的一大技术难题。统计分析发现断层破碎带井漏占渤海油田全部井漏的16%,堵漏一次成功率仅为46.6%。针对断层破碎带井漏的特点,结合海上工程实际,研制出了一种堵塞形成快、滤饼强度高的酸溶性高失水固化堵漏剂STP。该堵漏剂选用酸溶性高失水材料复配架桥材料、特种纤维材料和固化剂组成,主要成分为亚硫酸盐和氧化物,不含聚合物,可直接用海水配制。室内评价和现场应用表明,该堵剂能够封堵断层破碎带等不同尺寸的裂隙性漏失,承压能力达7 MPa,对钻井液性能影响小,酸溶率80%以上,而且配制工艺简单,便于现场操作,非常适合海上油田断层破碎带堵漏。

Mud losses in fault zone in Bohai Oilfield have long been a problem negatively affected drilling operation in this area. Statistics shows that 16% of mud losses in Bohai Oilfield occurred in fault zone, and only 46.6% of these mud losses were successfully controlled at the first try. A newly developed lost circulation material, STP, was used to control mud losses into the fault zone in Bohai Oilfield. STP is composed of acid-soluble high filtration rate material compounded with a bridging agent, a special fiber and a solidifier, and can quickly form a high strength hardened plug to stop mud losses. STP, without polymeric constituent, can be formulated directly with seawater. Laboratory study and the application of STP in Well BZ8-4-2 and Well BZ34-3-P2 showed that STP can be used to stop mud losses into fractures of different sizes in the said fault zone. The set LCM has a pressure bearing capacity of 7 MPa. STP has minor influence on the property of drilling fluid, and has a rate of acid solubility of more than 80%. STP is easy for field use and is very suitable for use in offshore mud loss control in fault zone.