运用气-液-液三相相平衡理论研究濮67气藏产水来源

濮67气藏非均质性严重,小断层发育,气水关系复杂。为了深入研究气藏产水来源,以水相为参考相,为描述水相的强极性,用活度和标准态逸度描述水相的逸度,建立含水凝析油气体系的气-液-液三相平衡的物质平衡和热力学模型,用建立的数学模型模拟濮气10井定容衰竭过程中凝析气饱和含水量。模拟结果表明,随压力降低,凝析气中含水量增加,在井口压力降至5MPa时,凝析气中含水量高达1.03 m3/104 m3,根据濮气10井的稳定产气量计算日产水量为1.7 m3,结合2次投产层位的稳定产水量判断产水来源。结果表明,S4上产水来源于地层隙间水和束缚水,S4下存在较小的活动水体,能量不大,产水主要来源于地层水。研究结果为气藏水动态监测和产水来源判断提供了理论支持。

Study on producing water source in Pu67 gas reservoir based on gas-gas-liquid 3-phase equilibrium

Pu67 gas reservoir features in severe anisotropism, abundant little faults and complicated gas-water relation. Water is taken as reference phase to probe into the reservoir source of producing water. Water fugacity is described by activity and standard fugacity to characterize the strong polarity of water. Material balance model and thermodynamics model of gas-gas-liquid 3-phase equilibrium of condensate gas with water are established in this paper to simulate saturated water content in condensate gas of well Puqi-10 during constant volume depletion. Saturated water content in condensate gas increases with the pressure decreasing. Saturated water content is as much as 1.03 m3/104 m3 when the pressure depletes to 5 MPa. Stable water production per day of well Puqi-10 is 1.7 m3 according to stable gas production per day. The water source of producing horizon can be determined by comparing saturated water content and stable water production per day. The result shows that producing water in S4S horizon is different from the water between the gaps and irreducible water, and there is a little water body in S4X horizon, so producing water mostly comes from formation water.