吉拉克凝析气田自流注气提高采收率方案研究

A RESEARCH ON THE PLAN OF ENHANCING RECOVERY IN JILAKE CONDENSATE GAS FIELD BY ARTESIAN GAS INJECTION

吉拉克凝析气田发育有两套含油气层系，上部为带油环、具正常压力、高凝析油含量的三叠系凝析气藏，下部为异常高压、低凝析油含量的石炭系凝析气藏。根据这两套油气层的特点，提出利用下部石炭系凝析气藏天然气对上部三叠系凝析气藏实施自流注气开发的设想，并围绕这一设想，进行了开采方式论证、室内实验、数值模拟等研究。研究结果认为：井下控制自流注气的开采方式对提高三叠系凝析气藏的凝析油和油环油采收率有显著效果，方案具有实施性。推荐的实施方案是：憋压１年，再自流注气开采２０年。其开发指标与衰竭式开采２０年的开发指标相对比，可提高三叠系凝析气藏凝析油采收率８５％、油环油采收率３２％、天然气采收率３９％。

Two sets of oil and gas bearing strata were found in Jilake condensate gas field, the upper part being the Triassic condensate gas reservoir with oil ring, normal formation pressure and high condensate content and the lower part being the Carboniferous condensate gas reservoir with abnormally high formation pressure and low condensate content. According to the properties of the two sets of oil and gas bearing strata, a thought of the artesian gas injection development of the upper Triassic condensate gas reservoir by use of the gas coming from the lower Carboniferous condensate gas reservoir is proposed and the demonstration of development scheme and the research on the laboratory analysis and mathematical simulation are carried out around such a thought. Through the research it is considered that the recovery method by downhole controlled artesian gas injection is of notable results for enhancing the recovery factors of both condensate and oil ring oil in the Triassic condensate gas reservoir, having operability. The recommended implementation plan is: producing by artesian gas injection may last for twenty years through suppressing pressure for one year. By means of correlating its development indexes with those of natural depletion for twenty years, it is found that in the Triassic condensate gas reservoir, the condensate recovery may be increased by 8.5%, the oil ring oil recovery by 3.2% and the natural gas recovery by 3.9%.