Research And Application Of Logging Evaluation Method For Igneous Oil And Gas Reservoirs

Igneous reservoirs have become an important field of oil and gas exploration and development in the world.China has developed several igneous rock oil and gas fields in Junggar Basin,Songliao Basin,Bohai Bay and other basins,among which the proved geological reserves of igneous rock oil and gas reservoirs in Junggar Basin alone have reached 300 million tons,showing a huge potential of oil and gas resources.However,due to the diverse lithology,complex reservoir space and pore structure of igneous rocks,there are still evaluation difficulties in the exploration and development,which restricts the efficient development of igneous oil and gas reservoirs.According to the investigation of the logging evaluation status of igneous oil and gas reservoirs in many basins,there are four main difficulties in the logging evaluation of igneous oil and gas reservoirs.First,the lithology of igneous rock is complex,and the identification rate is low.Second,the reservoir space and pore structure of the igneous rock reservoir are complex,and it is difficult to finely characterize the pore and fracture parameters.Third,due to the complex lithology,pore structure and other factors,the reaction ability of resistivity to fluid properties is weakened,and the coincidence rate of oil and gas layer logging interpretation is low.Fourth,the lack of systematic evaluation of igneous rock mechanical parameters and stress,cannot meet the evaluation needs of geological engineering integration.Using core experiment,logging,oil test,etc.,to study the difficult problems in the evaluation of igneous rocks in the northwest margin of Junggar Basin.The research contents include rock property identification of igneous rocks,reservoir property evaluation,oil and gas layer identification and saturation quantitative calculation,rock mechanical parameters and crustal stress evaluation.The types of igneous rocks in Junggar Basin are systematically summarized by core observation and core fragment identification.The response characteristics of typical lithological conventional logging,ESC and FMI are deeply analyzed.The typical lithology identification pattern map of igneous rock is established.Based on the sensitivity analysis of conventional logging curve to lithology identification,the N-DP intersection map and G-D-C ternary phase map are innovatively established,which provides a method for accurate identification of igneous rocks by conventional logging.Based on the comprehensive analysis of experimental data and imaging logging data,the characteristics of spatial combination of igneous rock reservoir are clarified.Innovatively using core casting parameters and electrical imaging fracture parameters to calibrate the fracture porosity calculated by dual lateral resistivity logging.Innovatively using electrical imaging to calibrate the secondary porosity calculated by conventional three porosity logging.The calculation accuracy of physical parameters of igneous rock reservoir is improved.Using gas logging,well logging,oil test and experiment,etc.,the gas measurement component analysis method,water resistivity normal distribution method,Poisson ratio-volume compression coefficient method and Hingle intersection diagram method are established,which improves the coincidence rate of oil and gas logging.In the view of the complex lithology and pore structure of igneous rock reservoir and the weakened reaction of resistivity to fluid properties,the variable m value study is adopted to improve the calculation accuracy of oil saturation.The J function method is used to solve the problem of evaluating oil saturation by non-electric method.Based on the theory of rock elasticity,the evaluation model of igneous rock rock mechanics parameters and crustal stress is systematically established by using the core mechanics test data and logging data.In addition,the reliability of the model is analyzed based on core test data and field fracturing data,which provides an important basis for rock mechanics parameter evaluation of igneous rock reservoir and fracturing engineering design.