With Oil Ring Bottom Condensate Gas Reservoir Development Mechanism

Bottom water gas condensate reservoir with oil rim exists widely all over the world and has high exploited value. At present, how to recover most oil in the oil rim and how to decrease the loss of condensate to the minimum degree are the major problems in the development of bottom water gas condensate reservoir with oil rim.There are several problems in development of bottom water gas condensate reservoir with oil rim:①Gas-water distribution is complex. In the whole water dynamics system, there are condensate gas, condensate oil, oil rim, dissolved gas and formation water and so on, and in the development process, bottom water coning, sudden advance of edge water, and sudden advance of oil rim oil into the gas easily appear;②Fluid phase is complex, gas condensate reservoir and the oil rim have different PVT properties, in the development process, phenomenon of retrograde condensation appears in the gas condensate reservoir, and the variation of formation fluid saturation is complex;③Fluid flow characteristics are complex, there is oil and gas single phase flow, oil-water, oil-gas and gas-water two-phase flow, and oil-gas-water three-phase flow;④Bottom water coning easily segments thin oil rim, which makes the development of oil rim difficult;⑤How to deal with fluid PVT characteristics of gas condensate reservoir with the oil rim in the numerical simulation better;⑥Conventional bedding simulation grid modeling methods can not Characterize of true distribution characteristics of thin oil rim;⑦The use of horizontal wells to develop oil rim can increase oil rim recovery and slow down bottom water coning rate, but the reasonable production parameters of horizontal well greatly influence the oil rim recovery and bottom water coning. The special development characteristics and challenges bring more difficulty for researching gas condensate reservoirs with oil rim.In this paper, bottom water gas condensate reservoir with oil rim is regarded as research object, aiming to accurately describe the distribution of these reservoir fluids, phase characteristics simulating and use horizontal wells to improve oil recovery. From the angle of gas condensate reservoirs geological characteristics, development characteristics and the development mode, through analyzing phase characteristics of gas condensate reservoir with oil rim, establishing mathematical model and resolution, researching mixed grid modeling technology, effect of sand heterogeneity degree on the development is analyze and the reasonable production parameters of horizontal well developing oil rim are optimized. Finally, the results of researching bottom water gas condensate reservoir with oil rim are applied to Yingmai 7-19 bottom water gas condensate reservoir with oil rim. The paper's main findings are as follows:(1) The development methods of bottom water gas condensate reservoir with oil rim at home and abroad are analyzed and the current numerical simulation of gas condensate reservoir is researched;(2) Fluid phase behavior theory of gas condensate reservoir is researched and adaptability of the fluid equation of state by sampling is carried on. Then, PVT experiment fitting and phase behavior of condensate gas and oil rim are researched. Fluid characteristics and fluid simulation are achieved by cap.condensate gas and oil rim with two PVT parameters and 9 components.(3) According to the flow mechanisms of bottom water gas condensate reservoir with oil rim, material balance principle and equilibrium principle, mathematical model of bottom water gas condensate reservoir with oil rim is established and the mathematical model is differenced and implicit solution is carried out;(4) Based on theory of modeling mixed grid, computer program of mixed grid is generated by computer language. The reservoir parameters are treated by the volume-weighted approach and fluid flow parameters are treated by tensor analysis. Distribution of oil rim is characterized in the way of mixed grid. Modeling technique of mixed grid is achieved and the reliability of the mixed grid is verified;(5) Mechanism model of bottom water gas condensate reservoir with oil rim is established and effect of reservoir heterogeneity on the development is analyzed;(6) Mechanism of horizontal wells developing oil rim is studied and reasonable parameters of condensate gas reservoir with oil rim developed by horizontal well are obtained;(7) The mixed grid geological model for Yingmai 7-19 bottom water gas condensate reservoir with oil rim is established, The case of oil rim developed by horizontal well is simulated by two PVT of oil rim and condensate gas,and the effect of horizontal well developing oil rim is evaluated.