文南油田注天然气提高原油采收率可行性研究

【作者】 黄泽贵；

【导师】 赵金洲； 刘一江；

【作者基本信息】 西南石油学院 ， 油气田开发工程， 2005， 博士

【摘要】 国内近年发现和未投入开发油田主要以低渗透油田为主,约占发现储量的50%—60%,其中特低渗透油藏在低渗油藏中占60%—70%。低渗透油藏储层物性差,注水压力高,难以实现注水开发,高效地开发这类油藏是一个世界性的难题。论文通过对文南低渗、高温高压挥发性油藏注气提高原油采收率的可行性研究,为文南油田的开发提供一条新的途径。 国内外对低渗透油藏注气提高原油采收率开展了一系列的室内研究和现场先导试验,并取得了一些成功的经验。但是,对于低渗、高温高压挥发性油藏注气提高原油采收率还没有见到相关的室内研究和现场试验报道。论文在对注气驱机理详细论述的基础上,开展了注气混相驱和非混相驱理论研究、室内实验评价和现场注气试验等工作,形成了低渗、高温高压挥发性油藏注气提高原油采收率研究方法和配套的高压注气工艺技术,为文南油田实施注气提高原油采收率提供了技术保证。可行性研究工作包括: 1.对目前石油工业界广泛采用的立方型状态方程的结构体系、适应性和精度进行了全面地分析,并选择出适用于气-液二相相平衡计算的状态方程。建立适合注气混相和非混相驱的相态模拟计算模型,对混相驱和非混相驱的机理进行了深入的分析; 2.进行了水驱、非混相气驱和非混相驱水气交替长岩心驱替实验,评价了不同的注入介质和水气交替对提高原油采收率的影响。同时,评价了注水、注气和水气交替注入的最大注入压差,从实验上证明了低渗透油藏不能实施水气交替注入的原因; 3.用细管实验确定气驱最小混相压力。设计了富化天然气驱细管实验,确定了天然气与地下原油混相所需的中间烃含量;开展了混相驱长岩心驱替实验,评价了混相条件下长岩心驱替原油采收率; 4.完成了流体相态拟合分析,建立了三维地质模型,并完成了选定先导试验区生产历史拟合。在此基础上,用三维三相多组分模型对文南油田注天然气和注入不同富化度天然气驱的开发效果进行了模拟研究; 5.分析了气驱过程中有机固相沉积机理,结合实验研究结果,对文南油田可能出现的固溶物沉积进行了研究分析; 6.根据氮气试注情况和对国内外天然气增压设备的调研,对现有天然气压缩机、注气井口、井下管柱及封隔器等能否满足文南油田注天然气的需要进行了分析; 7.用现金流量和换油率法对先导试验区进行了经济评价。 通过以上研究表明,文南油田低渗、高温高压透挥发性油藏注气可以大幅度地提高原油采收率;经济评价和对国内外天然气增压设备的调研也表明,文南油田注天然气具有良好的经济效益,现有天然气压缩机、注气井口、井下管柱及封隔器等均能满足文南油田高压注天然气的需要。本文所研究的内容已经被中石化总公司立为重大研究课题。其中,对文南低渗、高温高压油藏进行注入天然气提高原油采收率的研究成果已经在SPE上发表(见SPE77799)。更多还原

【Abstract】 Recently the oilfields discovered and not brought into development in our nation are mainly low-permeability oilfields, which account for about 50%-60% of the discovered reserves and of which the extreme low-permeability reservoirs occupy 60%-70%. The low-permeability reservoirs are difficult to be developed by water injection due to the poor physical properties and high injection pressure; therefore, how to develop this kind of reservoirs presents a worldwide problem. This paper, through the feasible research of EOR by gas injection in Wennan low-permeability、 high-temperature and high-pressure volatile reservoir, provides a new approach for the development of Wennan oilfield.Both in home and abroad, a series of laboratory studies and spot precursor trials about EOR in low-permeability reservoirs by gas injection have been performed, and achieved some successful experience. But there were no report of laboratory study and spot precursor trial about EOR in low-permeability, high-temperature and high-pressure volatile reservoir found. Based on the detailed dissertation of mechanism of gas injection flooding, we carried out the works of theory study of gas injection miscible flooding and immiscible flooding as well as laboratory experiment evaluation and spot gas injection trial. Consequently formed the research method of EOR by gas injection in low-permeability, high-temperature and high-pressure volatile reservoir and corresponding gas injection process and technics. Thereby provide the technology guarantee for EOR by gas injection in Wennan oilfield. The feasible research works are as follows:1. Roundly analyzed the structure system, applicability and precision of the cubic EOS which is now widely used by petroleum industry, choosed the EOS which is applicable to phase equilibrium calculation of gas-liquid two phase. Established the phase behavior simulation and calculation model for gas injection miscible and immiscible flooding, and embedded analyzed the mechanism of miscible and immiscible flooding;2. Carried out water flooding、 immiscible gas flooding and immiscible WAG long core displacement test, evaluated the influence of different injection medium and WAG on EOR. At the time, evaluated the maximum injection pressure differential of water injection、 gas injection and WAG, testified that low-permeability reservoirs can not be processed by WAG injection;3. Obtained the minimum miscible pressure according to slim-tube test. Designed the enriched gas drive slim-tube test, fixed the content of intermediate hydrocarbon that could make natural gas and formation crude oil miscible, performed the long core displacement test of miscible flooding, evaluated the crude oil recovery of long core displacement under thecondition of miscible;4. Completed the liquid phase behavior matching and analysis, established the three-dimensional geological model, and also completed the production history matching ofthe choosed precursor trial area. On this basis, simulated and studied the development effect of natural gas injection or different enrichment natural gas drive using three-dimensional and three-phase polycomponent model in Wennan oilfield;5. Analyzed the mechanism of organic solid deposition during gas flooding, and assisting with the results of experiment study, studied and analyzed the solid deposition might exist in the process of gas injection in Wennan oilfield.6. Based on nitrogen injection test and the researching of gas booster equipment home and abroad, analyzed whether the present natural gas compressors > gas injection wellhead > down-hole strings and packers etc, could all satisfy the requirements of gas injection in Wennan oilfield;7. Performed economy evaluation for the precursor trial area using cash flux method.The studies ahead indicated that the oil recovery of Wennan low-permeability ^ high-temperature and high-pressure volatile reservoir can be remarkably improved by natural gas injection. The economy evaluation and the research of gas booster equipment home and abroad also indicated that there will be a good economy benefit on natural gas injection in Wennan oilfield and all the present natural gas compressors > gas injection wellhead > down-hole strings and packers etc, could satisfy the requirements of gas injection in Wennan oilfield. The research in this paper has been established significant item by SinoPec. Especially, the study of enhanced oil recovery by natural gas injection in Wennan oilfield with low-permeability > high-pressure and high- temperature has been published in SPE.(SPE77799)更多还原