莫里青高凝油储层的压裂增产技术

Fracturing stimulation technology for reservoirs of thick and viscous crude in rift Moliqing

莫里青断陷属强水敏的高凝油油藏,原油凝固点大于45℃,含蜡量大于40％;粘土矿物复杂,水敏性较强,渗透率和孔隙度较低,采用常规压裂设计思路和常规压裂液体系,难以取得好的压裂效果。在系统分析储层特性、以往压裂实践的基础上,提出了一套强水敏高凝油油藏的压裂优化技术以及适合储层的压裂液体系。该技术使用保护储层加热的预前置液,防止压裂液降温引起原油结蜡伤害储层;使用水力裂缝优化技术,优化裂缝支撑半缝长;使用多级渐进式加砂程序和较高的砂液比提高裂缝的导流能力;使用复合的粘土稳定剂防止粘土膨胀;选用快速破胶、彻底反排的优质压裂液以减少压裂液对储层的伤害。该技术在莫里青断陷实验3井次,取得了明显的增产效果。

Rift Moliqing is a highly water sensitive reservoir, its crude oil setting point is over 45℃, and wax content is over 40%. Because of the complex clay minerals, high water sensitivity, low permeability and porosity, the conventional fracturing design and fracturing fluid system is ineffective. A set of optimal fracturing technologies and the suitable fracturing fluid systems are presented, based on the comprehensive analysis of formation characteristics and the fracturing practices. This technology involves: 1. using of natural pre-flushing fluid to prevent wax deposition, thus avoid formation damage; 2. using of hydraulic fracture-optimization technology to optimize the supporting length; 3. using of the multi-stage progressive sand adding program and higher sand to liquid ratio to improve the fracture flow diverting ability; 4. using of the composite clay stabilizer to prevent clay swelling; 5. selecting the fast gel breaking, totally reverse-displacing fracturing fluid to minimize formation damage. This technology was used in 3 wells in rift Moliqing, and remarkable stimulation results were obtained.