复杂多孔介质主流通道定量判识标准

为判识油气储集层中复杂多孔介质的主流通道类型,利用试井解释获取的综合渗透率与岩心测试(或测井解释)得到的基质渗透率的比值定义了“主流通道指数”,同时基于流量等效原理建立了相应的数学模型,提出了主流通道分类方法,实现了储集层流动通道类型的定量表征,并通过典型气藏实例分析验证了该方法的有效性。研究表明,“主流通道指数”能够定量划分流动通道类型:该指数小于3,基质孔隙为主要流动通道;该指数为3~20,流动通道以裂缝为主、基质孔隙为辅;该指数大于20可视裂缝为唯一渗流通道。典型气藏的动态分析显示,“主流通道指数”可用于评价多孔介质流动通道类型,进而指导气藏分类开发、规避气藏开发风险。

中国超深层大气田高质量开发的挑战、对策与建议

中国超深层天然气勘探开发潜力巨大,已成为天然气业务增储上产、效益增长的主体和未来油气上游业务发展的重要战略领域,实现其高质量开发意义重大。为此,通过对气田开发特点、开发效果进行梳理和评价,明确了超深层大气田实现高质量开发面临的挑战,针对制约气田开发效果的关键认识和技术瓶颈,基于室内物理模拟实验、储层评价、气藏动态评价、数值模拟研究以及国内外气田开发的经验与教训,提出了超深层大气田高质量开发的要求,以及具体的对策与建议:(1)强化气藏前期评价,落实可动用储量,确定气田合理的产能规模,避免功能浪费;(2)优化井位部署与单井合理配产,实现气藏均衡开发,以获得高储量动用率和采收率;(3)持续进行钻完井技术及有针对性的储层改造技术攻关,通过前者进一步缩短钻完井周期、使开发成本不断下降,通过后者进一步提高单井产量、提高储量动用程度,实现低品位储量的有效动用;(4)创新管理模式,建立超深层大气田开发建设和生产运行的科学程序,严格控制产量上限指标,更加突出质量效益。结论认为,高质量开发超深层大气田是一项艰巨复杂的系统工程,勘探、开发技术和管理模式的持续创新是最终实现该目标的必由之路。

孔隙型砂岩储集层主流通道指数及矿场应用

综合利用试井解释、生产动态分析以及覆压孔渗、气水相渗和高压压汞等检测技术,定量评价了孔隙型砂岩储集层地层条件下有效渗透率与常规基质渗透率、含水饱和度的关系,确定了不同渗透率孔隙型砂岩储集层的主流通道指数范围;建立了孔隙型砂岩储集层地层条件下有效渗透率评价方法、孔隙型砂岩储集层储量动用程度与主流通道指数关系图版。研究表明:孔隙型砂岩储集层主流通道指数与常规基质渗透率、含水饱和度密切相关,常规基质渗透率越低、含水饱和度越高,主流通道指数越低。常规基质渗透率大于5.0×10-3μm2时,主流通道指数一般大于0.5;常规基质渗透率为1.0×10-3~5.0×10-3μm2时,主流通道指数为0.2~0.5;常规基质渗透率小于1.0×10-3μm2时,主流通道指数通常小于0.2。孔隙型砂岩储集层地层条件下有效渗透率评价方法可以对新发现气藏或未开展试井测试的气藏实现快速评价并判识致密砂岩气;孔隙型砂岩气藏储量动用程度与主流通道指数关系图版可为可动用储量评价及井网加密提供依据,为气藏开发评价以及合理开发技术政策制定提供技术支持。

Quantitative criteria for identifying main flow channels in complex porous media

To identify the type of main flow channels of complex porous media in oil and gas reservoirs,the"main flow channel index"is defined as the ratio of comprehensive permeability obtained from well test to matrix permeability obtained from core analysis or well logging.Meanwhile,a mathematical model is established based on equivalent flow assumption,the classification method for main flow channels is put forward,and quantitative characterization of main flow channels is realized.The method has been verified by analysis of typical gas reservoirs.The study results show that the"main flow channel index"can quantitatively classify types of flow channels.If the index is less than 3,the matrix pore is the main flow channel;if the index is between 3 and 20,the fracture is the main flow channel and the matrix pore acts as the supplement one;if the index is more than 20,the fracture is the only seepage channel.The dynamic analysis of typical gas reservoirs shows that the"main flow channel index"can be used to identify the type of flow channel in complex porous media,guiding the classified development of gas reservoirs,and avoiding development risk.

Main flow channel index in porous sand reservoirs and its application

Based on well test interpretation,production performance analysis,overburden permeability and porosity test,gas-water core flooding test and high-pressure mercury injection,a quantitative correlation has been built of in-situ effective permeability with routine permeability and water saturation,and the ranges of Main Flow Channel Index(MFCI)are determined for different permeability levels in porous sand gas reservoirs.A new method to evaluate the in-situ effective permeability of porous sand reservoir and a correlation chart of reserves producing degree and main flow channel index are established.The results reveal that the main flow channel index of porous sand gas reservoirs has close correlation with routine matrix permeability and water saturation.The lower the routine matrix permeability and the higher the water saturation,the lower the MFCI is.If the routine matrix permeability is greater than 5.0×10-3,the MFCI is generally greater than 0.5.When the routine matrix permeability is from 1.0×10-3 to 5.0×10-3,the MFCI is mainly between 0.2 and 0.5.When the routine matrix permeability is less than 1.0×10-3,the MFCI is less than 0.2.The evaluation method of in-situ effective permeability can be used to evaluate newly discovered or not tested porous sand gas reservoirs quickly and identify whether there is tight sand gas.The correlation chart of reserves producing degree and main flow channel index can provide basis for recoverable reserves evaluation and well infilling,and provide technical support for formulation of reasonable technical policy of gas reservoir.

Efficient development strategies for large ultra-deep structural gas fields in China

Through analyzing the development of large ultra-deep structural gas fields in China,strategies for the efficient development of such gas fields are proposed based on their geological characteristics and production performance.According to matrix properties,fracture development degree and configuration between matrix and fractures,the reservoirs are classified into three types:single porosity single permeability system,dual porosity dual permeability system,and dual porosity single permeability system.These three types of gas reservoirs show remarkable differences in different scales of permeability,the ratio of dynamic reserves to volumetric reserves and water invasion risk.It is pointed out that the key factors affecting development efficiency of these gas fields are determination of production scale and rapid identification of water invasion.Figuring out the characteristics of the gas fields and working out pertinent technical policies are the keys to achieve efficient development.The specific strategies include reinforcing early production appraisal before full scale production by deploying high precision development seismic survey,deploying development appraisal wells in batches and scale production test to get a clear understanding on the structure,reservoir type,distribution pattern of gas and water,and recoverable reserves,controlling production construction pace to ensure enough evaluation time and accurate evaluation results in the early stage,in line with the development program made according to the recoverable reserves,working out proper development strategies,optimizing pattern and proration of wells based on water invasion risk and gas supply capacity of matrix,and reinforcing research and development of key technologies.

川中高石梯区块灯影组四段古岩溶带及内部储层分布特征

四川盆地震旦系灯影组四段(灯四段)在表生期岩溶作用影响下纵向岩溶分带特征明显,不同岩溶带储层发育程度差异较大,有必要精细刻画古岩溶带内部结构,进一步明确优质储层的分布。综合岩心、地震、成像测井等资料,基于地下水运动方式及孔、洞、缝发育特征,开展了高石梯区块灯四段古岩溶带划分,建立了古岩溶带厚度与古岩溶地貌相对高程的关系,并细分水平潜流亚带,分析不同期水平潜流亚带优质储层的发育特征,分区优选了有利古岩溶亚带。研究表明,高石梯区块灯四段古岩溶地貌越高,垂直渗流带厚度越大、水平潜流带厚度越小。受古岩溶潜水面周期下降影响,水平潜流带内发育3期水平潜流亚带,上部水平潜流亚带1、亚带2优质储层发育程度优于亚带3。根据沉积相、古岩溶地貌及优质储层展布特征,将高石梯区块划分为3个区域。区块西侧(1区)各岩溶带和亚带优质储层均较发育,优质储层累计厚度超50 m,为最有利区域;区块东侧(2区)优质储层仅发育于垂直渗流带,优质储层累计厚度为15~20 m;区块南侧(3区)优质储层主要发育于垂直渗流带和水平潜流亚带1,优质储层累计厚度为30~40 m。不同区域优质储层发育的岩溶带、亚带存在差异,应采用不同的开发技术政策。

超深层碳酸盐岩气藏产能预测模型及影响因素研究

超深层碳酸盐岩气藏具有储集介质多样、非均质性强和高温高压等典型特征,且普遍采用斜井开发,导致气井产能评价难度大。考虑该类气藏的多重储集介质、应力敏感性、非线性渗流、阈压效应和井斜等因素,基于Forchheimer气相微分方程、应力敏感和气相渗流物理模拟实验数据建立三项式产能预测模型,对不同区域、不同类型碳酸盐岩储层的气井产能进行预测,并分析上述因素对产能的影响规律。结果表明:孔隙型和低渗透孔洞型储层受阈压效应的影响,缝洞型和高渗透孔洞型储层受非线性渗流的影响,因此三项式产能预测模型更适合储层类型多样的超深层碳酸盐岩气藏;不同类型储层表现出不同程度的应力敏感性和非线性渗流特征,需进行各类储层岩心的物理模拟实验确定产能方程所需的各项参数;井斜会产生负表皮因子影响气井产能,当井斜角大于55°时,各类储层的气井产能开始快速提升,且对缝洞型储层的改善效果最明显;阈压效应的产能抑制作用在低压差阶段很强,而应力敏感性和非线性渗流的影响主要体现在高压差阶段;启动压力梯度和非线性渗流系数分别为0.01~0.048MPa/m和10^(9)~10^(12)m^(-1)时显著抑制气井产能,而应力敏感造成的产能损失较稳定;影响气井产能的主控因素是表皮系数和地层系数,而开发阶段的非线性渗流效应对高渗透储层以及阈压效应对低渗透储层的影响也较为显著。