摘要
页岩气主要以吸附状态和游离状态两种形式赋存于发育大量天然微裂缝的页岩中。为此,分别考虑裂缝系统和基质系统的流体性质和储层性质,建立了考虑吸附相体积随地层压力变化的裂缝性页岩气藏物质平衡方程。实例计算结果表明:较之于改进后的物质平衡方程,King提出的物质平衡方程由于未考虑裂缝体系和吸附相体积,储量计算结果偏小;Williams提出的物质平衡方程未考虑裂缝体系,储量计算结果偏大;刘铁成提出的物质平衡方程未考虑吸附相体积,裂缝系统储量偏小;改进的物质平衡方程同时考虑了裂缝体系和吸附相体积两因素,当吸附相密度增大时,页岩气藏吸附气储量就增大,而总地质储量略有减小,而储层温度、压力、孔隙半径与吸附相密度的关系及最终对储量计算的影响还有待进一步研究。结论认为,考虑裂缝体系和吸附相体积对于页岩气藏物质平衡方程的建立和应用十分必要。
Shale gas is stored as gas of adsorbed and free state in shale formations with numerous developed natural microfractures. In view of this, through the analysis of the fluid and reservoir properties of the fracture and matrix systems respectively, a modified material balance equation was worked out for fractured shale gas reservoirs considering the adsorbed phase volume changing along with the formation pressure. The calculation results in case histories were compared with those in literatures with neither the fracture system nor adsorbed-phase volume considered, Kingrs equation presented smaller volumes of shale gas reserves with the fracture system not considered, such reserves estimated By Williamsrs method were larger and with the adsorbed-phase volume not con- sidered, such reserves calculated by Liu Tiechengr s method were smaller. However, the modified material balance equation takes both the fracture system and adsorbed-phase volume into consideration. Therefore, as the adsorbed-phase density rises, the adsorbed gas reserves increases in a shale gas reservoir, and the total geological reserves slightly decreases. Whereas the relationship needs to be further studied among the formation temperature, pressure, pore radius, and adsorbed-phase density, as well as their impacts on the final reserve calculation results. In summary, it is essential to take the fracture system and the adsorbed-phase volume into account when establishing and applying the material balance equation for shale gas reservoirs.
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2013年第12期66-70,共5页
Natural Gas Industry
基金
国家杰出青年科学基金"油气藏渗流力学"(编号:51125019)
关键词
页岩气
吸附相
裂缝(岩石)
基质
系统
物质平衡方程
储量
计算
shale gas, adsorbed-phase volume and density, fracture （rock）, matrix, fracture system, material balance equation, reserves, calculation
