长春油田X断块气顶油藏型储气库注气能力评价

Evaluation of gas injection capacity of gas cap reservoir type gas storage in X-fault block of Changchun Oilfield

长春油田X断块油藏符合废弃油气藏改建储气库标准,注气井的产能评价对储气库建设起着重要作用,是储气库建设方案的编制和生产管理的核心指标。目前主要采用矿场统计、数值模拟、理论计算、油气层测试等途径确定单井注入能力,X断块现有生产资料和测试资料无法确定单井注入能力,只能通过理论计算确定单井注气能力。理论计算方法主要分为基于稳态的理论公式法和基于不稳态的数值模拟法,考虑到气藏压力对地层天然物性参数的影响,拟采用数值模拟方法评价X断块单井注气能力。在调研国内外同类油藏生产特征以及长春X断块地质特征和开发现状基础上,综合考虑压力对天然物性影响和Forchheimer效应的影响,基于考虑非达西效应的渗流模型,采用指数网格对地层划分,基于有限差分法对模型离散建立了关于地层压力的方程组,求解方程组利用地层压力计算井底产量。为检验模型可靠性,选取其他工区测试资料,按开井期间流压反算阶段产量,将预测阶段平均产量与测试产量进行对比,结果显示误差较小,验证了模型准确性,最后采用工区参数计算了X断块不同注气压力下注气量,建立了单井注气能力与注气压力二项式计算公式。该研究可以为工区储气库开发技术政策制定提供理论依据。

The X-fault block oil reservoir in Changchun Oilfield complies with the standard for the conversion of abandoned oil and gas reservoirs into gas storage.It is very important to evaluate gas injection well productivity for the construction of gas storage,and is the core index for the preparation of construction plans and production management of gas storage.At present,the injection capacity of a single well is mainly determined by means of mine statistics,numerical simulation,theoretical calculation,oil and gas layer testing,etc.The injection capacity of a single well can not be determined by the existing production data and test data of the X-fault block,but can only be determined through theoretical calculation.Theoretical calculation methods are mainly divided into the theoretical formula method based on steady state and the numerical simulation method based on unsteady state.Considering the influence of gas reservoir pressure on the natural physical parameters of the formation,the numerical simulation method was used in this paper to evaluate the gas injection capacity of a single well in X-fault block.On the basis of investigating the production characteristics of similar oil reservoirs at home and abroad and the geological characteristics and development status of X-fault block of Changchun Oilfield,comprehensively considering the influence of pressure on natural physical properties and the Forchheimer effect,based on the seepage model considering non-Darcy effect,the exponential grid was used to divide the formation,and a system of equations about formation pressure was established based on the finite difference method to discretize the model,and the system of equations was solved to calculate the bottom hole production using the formation pressure.In order to test the reliability of the model,the test data of other work areas were selected,and the stage production was back-calculated according to the flow pressure during the well opening period.The average production in the predicted stage was compared with the test production.The comparison shows that the error is small,which verifies the accuracy of the model.Finally,based on the parameters of the work area,the gas injection volume under different gas injection pressure in X-fault block was calculated,and the binomial calculation formula of single well gas injection capacity and gas injection pressure was established.The study can provide a theoretical basis for the formulation of technical policies for gas storage development in the work area.