【作者】 叶礼友；

【导师】 魏国齐； 熊伟；

【作者基本信息】 中国科学院研究生院（渗流流体力学研究所） ， 流体力学， 2011， 博士

【摘要】 本文以川中须家河组低渗砂岩含水气藏为研究对象,针对该气藏产水严重的问题,通过常规压汞、恒速压汞、核磁共振测试技术、微观模型实验和高压岩心驱替实验等,系统地研究了储层微观孔隙结构特征、产水机理和储层压力条件下的渗流规律,结合储层静、动态特征,形成了一套储层综合分类评价方法。取得以下主要研究成果：(1)须家河组低渗砂岩气藏储层小于0.1微米的孔喉占孔隙体积30%-70%,喉道既是气体重要的渗流通道,也是气体重要的储集空间,这种孔隙结构特征决定了储层致密高含水。(2)提出可动水饱和度的概念,将原始含水分成束缚水和可动水,建立了可动水饱和度的核磁共振测试方法和测井解释方法。(3)建立了可动水饱和度预测气井产水特征的关系：可动水饱和度小于6%,对应的气井基本不产水；介于6%-8%之间,少量产水；介于8%～11%之间,产水量较大；大于11%,严重产水；该成果与川中须家河组气井产水特征吻合,可用于预测气井开发过程中的产水特征,指导制定合理的气井开发方案和工艺措施,达到有效防水和控水的目的。(4)低渗砂岩气藏地层条件下气体滑脱效应弱,应力敏感性弱；含水饱和度大于60%时,气体渗流表现出低渗透液相非线性渗流特征；含水饱和度在40%左右时,气体渗流特征发生明显转变；小于30%时,出现显著的气体渗流特征,高流速时会产生紊流现象。(5)气、水相对渗透率不仅是含水饱和度的函数,还是压力梯度的函数。气相相对渗透率随压力梯度的增大而减小,水相相对渗透率随压力梯度的增大而增大,在此基础上建立了低渗砂岩气藏气水两相渗流模型,该模型真实反映储层渗流特征,应用该模型预测了气井未来生产动态。(6)根据低渗砂岩含水气藏储层的静、动态特征,建立了包括渗透率、孔隙度、含气饱和度、主流喉道半径、阈压梯度和可动水饱和度六个特征参数的储层评价参数体系,形成了新型的低渗砂岩气藏储层多参数综合分类评价方法,制定了须家河组低渗砂岩气藏储层评价图版,方便现场应用,为川中须家河组低渗砂岩含水气藏储层优选打下坚实基础,对于指导气田高效开发具有重要意义。更多还原

【Abstract】 Xujiahe low permeability sandstone gas reservoirs in central Sichuan basin produced a lot of water in the development process. Aiming at this issue, the microscopic pore structures of reservoir and percolation mechanism in reservoir pressure are studied, and a new reservoir evaluation method is formed combined with static and dynamic reservoir characteristics. The following key findings are achieved:(1) Pores less than 0.1 micrometer diameter are accounted for 30%-70% of pore volume in Xujiahe low permeability sandstone gas reservoirs; Throat is not only gas flow channel, but also an important gas storage space. This pore structure determines the tight and high water saturation reservoirs.(2) The concept of movable water is proposed, which divides raw water into bound water and movable water; Movable water saturation NMR test and well logging interpretation method are proposed.(3) Method of using reservoir movable water saturation to predict water production feature of gas well is established:gas well where movable water saturation is below 6% does not produce water; For movable water saturation between 6% to 8%, gas well yields a few water; For movable water saturation between 8% to 11%, gas well yields a lot of water; When movable water saturation is greater than 11%, gas well produces water severely. The results can be used to predict gas wells water production features during the development, guiding to a reasonable development plan, and to achieve effective water control purposes.(4) The gas slippage effect under the reservoir conditions can be neglected in low permeability sandstone gas reservoir and stress sensitivity is weak. More than 60% water saturation, the gas phase flow showed liquid nonlinear seepage characteristics; At about 40% water saturation, gas flow characteristic is gradually showed; less than 30% water saturation, gas flow characteristics is significantly appeared, and high velocity will produce turbulent flow phenomenon.(5) Gas and water relative permeability is not only a function of water saturation, but also the function of pressure gradient. Gas relative permeability decreases with pressure gradient, while the water relative permeability increases with the pressure gradient. A gas-water two-phase flow model of low permeability sandstone gas reservoir is established. Future gas production dynamics of gas well is predicted based on this new model.(6) According to the static and dynamic features of low permeability sandstone gas reservoirs, a reservoir evaluation parameter system including six parameters is established:permeability, porosity, gas saturation, mainstream throat radius, threshold pressure gradient and mobile water saturation. A new type of multi-parameter comprehensive reservoirs evaluation method for low permeability sandstone gas reservoirs is formed. This result lays a solid foundation for reservoir evaluation and selection for Xujiahe low permeability sandstone gas reservoirs in Sichuan basin.更多还原