利用测录井资料计算气油比定量识别低孔渗储层流体性质

Calculating Gas Oil Ratio with Logging Data and Quantitatively Identify Fluid Properties of Low Porosity and Permeability Reservoirs

低孔渗储层储集空间小,且含油气饱和度低,致使油气测录井响应特征差异小,储层流体性质识别困难。X凹陷油气藏埋藏深,均发育于3800m以下,具有储层物性差、非均质性强、孔喉结构复杂及油气水分布不规律的特征。气测录井是直接测定钻井液中可燃气体各组分含量的一种录井方法,能有效反映油气藏的气油比。基于录井气测组分含量(TG、C1)和MDT泵抽气油比,建立气油比与气测组分的响应方程,并与各常规测井响应方程组成超定线性方程组,采用最优化算法计算储层的气油比,结合油气藏类型识别标准,实现定量判断储层流体性质的目的。在实际井的应用中,利用测录井资料计算的气油比与MDT泵抽分析结果相比,相对误差小于7.80%,说明最优化计算的气油比合理、可靠,该方法具有较好的应用和推广价值。

Low porosity and permeability reservoirs are characterized by small reserving space and low oil and gas saturation,which leads to small difference between oil and gas logging response and difficulty in reservoir fluid properties identification.The oil and gas reservoirs are deeply buried and developed below 3800 m in X sag,which are characterized by poor physical properties,strong heterogeneity,complex pore throat structure and irregular distribution of oil,gas and water.Gas logging is capable of directly measuring the content of each component of combustible gas in drilling fluid,which can effectively reflect the gas-oil ratio of oil and gas reservoirs.Response equations of gas-oil ratio and gas components are established based on the contents of gas components(TG,C1)measured by mud logging and the gas-oil ratio measured by MDT pump.Then overdetermined linear equations are established with various conventional logging response equations.Consequently,the gas-oil ratio of the reservoir is calculated by using the optimization algorithm,so as to quantitatively identify the fluid property of the reservoir combining with the identification standard of oil and gas reservoir type.In the application of the actual wells,the gas-oil ratio calculated by logging data is compared with the MDT pumping analysis result,and the relative error is less than 7.80%.This shows that the optimized calculation of gas-oil ratio is reasonable and reliable.This method is effective and worth promoting.