摘要
青海涩北气田为第四系浅层生物成因气田,由于胶结疏松、储层成岩性差、受压后易产生变形,造成孔隙度和渗透率降低。通过对岩样在覆压条件下的孔隙度和渗透率测试,分析了涩北气田疏松砂岩储层孔隙度和渗透率随有效应力的变化特征,指出孔隙度与有效应力呈二次多项式的关系,无因次渗透率在低压段下降较快,与有效应力呈指数关系,在高压段下降减缓,与有效应力呈乘幂关系。气田衰竭开采到后期,由于气层压力下降引起储层岩石压实,中、深部储层孔隙度相对值下降约10%,渗透率下降到初始值的0.1～0.6;这些变化对气田的生产将产生较大的影响,因岩石变形将使气井产能平均降低47.1%。对涩北一号气田模拟计算表明:考虑岩石变形将使气田稳产年限缩短3a,到稳产期末和开采30a时的采出程度分别减少6.45%和5.47%。
Qinghai Sebei gas field is a shallow biogenetic gas field in the Quaternary formation, and its reservoirs are easilyprone to be deformed because of unconsolidated sandstones and poor lithologiesy, which results in obvious reduction of porosity and permeability during the process of pressure change. By overburden pressure experiments, porosity and permeability variation characteristics of Sebei unsolidated sandstone reservoirs isare analyzed. Therelationship of porosity and,effective stress is binomial. Dimensionless permeability reduces very quickly at the low pressure stage; however, it reduces slowly atat the high pressure stage. And at these two different stages, the relationships of permeability and effective stress are different, the former is exponential and the latter is the relationship of permeability and effective stress of is power. At the later period of gas field development, porosity will reduce by 10 percent, for gas reservoir pressure reduction and permeability will reduce to 0.1-0.6 times of original values and , whichit wwill influence gas production greatl_y-reduce gas weli productivity by 47.1 percent. Simulation results show that, when rock deformation is considered during gas field development, the stable production period will reduce 3 years and recovery percent of reserves at the end of the stable production period and at 30 years will reduce respectively by 6.45 percent and 5.47 percent, respectively.
出处
《天然气地球科学》
EI
CAS
CSCD
2008年第1期141-144,共4页
Natural Gas Geoscience
基金
中石油股份公司项目“涩北气藏储层开发机理与实验研究”(编号:040126-1)资助
关键词
疏松砂岩
涩北气田
储层
应力敏感性
产能
开发
Unconsolidated sandstone
Sebei gas field
Stress sensitivity
Productivity
Gas field development.
