摘要
针对深层高演化气页岩储层勘探和潜力评价的需求,通过高温高压模拟实验探讨了泥页岩在深层高演化阶段的成烃规律和孔隙演化。研究表明,高压条件下富有机质泥页岩中的纳米级微孔隙随温度和压力的升高不断增加,增加高峰与气态及液态烃产率高峰相一致,并导致页岩孔隙率升高,但进入高—过成熟阶段后页岩孔隙率将随模拟条件的进一步升高而降低。与微孔隙相反,页岩中的微米级毛细孔和巨孔随模拟温度或压力的升高不断减少,指示深层条件不利于游离气的储存,而该阶段微孔隙和表面积的显著增加,可弥补随温度和压力升高吸附能力下降引起的页岩吸附态天然气的减少,从而使深层页岩仍然具有较高的页岩气潜力。模拟样品黄铁矿、白云石等组分中发现大量次生微孔隙,证明页岩碎屑及矿物基质在深层演化阶段也能形成丰富的次生微孔隙,作为烃源岩页岩在演化过程中能形成大量酸性流体,有利于次生孔隙的发育。
Aiming at the demand of exploration and potential evaluation of deep high-evolution gas shale reservoirs,high temperature and high pressure simulation experiments were carried out to explore the hydrocarbon generation laws and pore evolution of shale in the deep high-evolution stage.The results show that nano-scale micro-pores in organic-rich mudstone and shale increase with temperature and pressure rising under high pressure conditions,and the peak is consistent with the yield peak of gaseous and liquid hydrocarbons,leading to the increment of shale porosity.However,shale porosity is decreased with further enhanced simulation conditions in high and over-maturity stages.Contrary to micro-pores,micron pores and giant pores are reduced with the simulation temperature or pressure rising,indicating that deep conditions are not conducive to free gas storage.However,micro-pores and surface area are significantly increased in this stage,which can make up for the reduction of adsorbed natural gas in shale caused by the decrease of adsorption capability with temperature and pressure rising,so that deep shale still has a high potential of shale gas.A large number of secondary micro-pores are found in pyrite,dolomite and other components in simulation samples,proving that abundant secondary micro-pores can also be formed in shale debris and mineral matrix during the deep evolution stage.A large number of acidic fluids can be generated in the shale as source rocks during the evolution,favorable to the development of secondary pores.
出处
《石油学报》
EI
CAS
CSCD
北大核心
2016年第2期172-181,共10页
Acta Petrolei Sinica
基金
国家重点基础研究发展计划(973)项目(2012CB214704-02)
国家重大科技专项(2011ZX05008-002-22)
甘肃省重点实验室专项(1309RTSA041)资助
关键词
孔隙演化
页岩储层
生烃模拟
高演化
富有机质源岩
pore evolution
shale reservoirs
hydrocarbon generation simulation
high evolution
organic-rich source rocks
