深层—超深层海相碳酸盐岩成储成藏机理与油气藏开发方法研究进展

Research advances on the mechanisms of reservoir formation and hydrocarbon accumulation and the oil and gas development methods of deep and ultra-deep marine carbonates

基于钻井、地震、测井、测试以及实验分析等新资料,针对中西部叠合盆地深层—超深层海相碳酸盐岩层系成储、成藏和油气藏高效开发面临的关键科学问题开展持续攻关。研究表明:(1)断裂主导形成的储集体和古老层系白云岩储层是深层—超深层海相碳酸盐岩两类重要的储层;以断裂为主导形成的规模储集体,根据成因可进一步分为3种类型:断裂活动过程中构造破裂形成的缝洞储集体、致密碳酸盐岩受断裂和流体双重改造形成的储集体与早期丘滩等高能相带受断裂和流体改造形成的储层;优势丘滩相、早期白云石化和溶蚀、酸性流体环境、膏盐岩封盖和超压是优质白云岩储层形成和保持的关键。(2)中国中西部叠合盆地海相碳酸盐岩层系富有机质页岩主要发育于被动陆缘深水陆棚、碳酸盐缓坡等环境中,构造-热体制是控制深层—超深层油气藏赋存相态的重要因素,改造型动力场控制中西部叠合盆地深层—超深层海相碳酸盐岩油气成藏与分布。(3)普光等高含硫酸性气田开发过程中硫析出堵塞井筒,采用井筒溶硫剂配合连续油管解硫堵效果明显;基于沉积模拟的双重介质建模数模一体化技术可以精细刻画水侵前缘空间展布及变化,并据此提出气井全生命周期调、排、堵控水对策。(4)超深断控缝洞油气藏开发过程中,储层应力敏感,渗透率随压力下降而显著降低,产量递减较快;凝析气藏相态变化快,压降显著影响凝析油采出程度;据此提出“注水+注天然气”重力驱油藏开发方法和“高注低采”天然气驱凝析气藏开发方法;采用分层次约束、逐级地质建模和流-固-热耦合的复合介质数值模拟有效提高了油气藏开发生产动态模拟的预测精度。

Based on the new data of drilling,seismic,logging,test and experimental analysis,the key scientific problems in reservoir formation,hydrocarbon accumulation and efficient oil and gas development methods of deep and ultra-deep marine carbonate strata in the central and western superimposed basin in China have been continuously studied.(1)The fault-controlled carbonate reservoir and the ancient dolomite reservoir are two important types of reservoirs in the deep and ultra-deep marine carbonates.According to the formation origin,the large-scale fault-controlled reservoir can be further divided into three types:fracture-cavity reservoir formed by tectonic rupture,fault and fluid-controlled reservoir,and shoal and mound reservoir modified by fault and fluid.The Sinian microbial dolomites are developed in the aragonite-dolomite sea.The predominant mound-shoal facies,early dolomitization and dissolution,acidic fluid environment,anhydrite capping and overpressure are the key factors for the formation and preservation of high-quality dolomite reservoirs.(2)The organic-rich shale of the marine carbonate strata in the superimposed basins of central and western China are developed in the sedimentary environments of deep-water shelf of passive continental margin and carbonate ramp.The tectonic-thermal system is the important factor controlling the hydrocarbon phase in deep and ultra-deep reservoirs,and the reformed dynamic field controls oil and gas accumulation and distribution in deep and ultra-deep marine carbonates.(3)During the development of high-sulfur gas fields such as Puguang,sulfur precipitation blocks the wellbore.The application of sulfur solvent combined with coiled tubing has a significant effect on removing sulfur blockage.The integrated technology of dual-medium modeling and numerical simulation based on sedimentary simulation can accurately characterize the spatial distribution and changes of the water invasion front.Afterward,water control strategies for the entire life cycle of gas wells are proposed,including flow rate management,water drainage and plugging.(4)In the development of ultra-deep fault-controlled fractured-cavity reservoirs,well production declines rapidly due to the permeability reduction,which is a consequence of reservoir stress-sensitivity.The rapid phase change in condensate gas reservoir and pressure decline significantly affect the recovery of condensate oil.Innovative development methods such as gravity drive through water and natural gas injection,and natural gas drive through top injection and bottom production for ultra-deep fault-controlled condensate gas reservoirs are proposed.By adopting the hierarchical geological modeling and the fluid-solid-thermal coupled numerical simulation,the accuracy of producing performance prediction in oil and gas reservoirs has been effectively improved.