Research On Evaluation Method Of Basin-scale Tight Gas Sands Resources

With the rapid development of China's economy,the demand for energy is increasing year by year.The conventional oil and gas resources have been unable to meet the needs of economic development,making our country pay more and more attention to the exploitation and utilization of unconventional natural gas resources such as tight sandstone gas.Because of the particularity of gas resources in tight sandstone,the distribution of gas reservoir near source is not controlled by structural traps;the reservoir is dense and the gas flow ability is weak;the gas reservoir area is large.The evaluation method of tight sandstone gas resources is obviously different from the conventional resources evaluation methods and parameter systems.The resources evaluation of tight sandstone gas in China is mainly based on the conventional resource evaluation method and some revisions are made in the local area.There is no mature understanding on the applicability of the method and the difference of parameter setting in the whole.Tight gas resource evaluation methods include the Delphi method,analogous basin geologic condition analogy method,basin residual resource analysis method,natural gas dispersion equilibrium calculation method and so on.In this paper,based on the national major oil and gas project,based on the research of mature and dense sandstone gas exploration area in North America,the applicability of the method,the reconstruction parameter system,the results of comparison and evaluation are discussed.In this paper,volume method,analogy method and resource triangle method,are applied to the evaluation of tight sandstone gas resources.The advantage of the volume method is that the parameters are directly related to the existence state of oil and gas,and the spatial distribution of resources is clear.The disadvantage is that the parameters are highly dependent on the exploration degree.The advantage of the analogy method is that the principle is reliable,the evaluation process is simple and fast,and it is suitable for the low middle exploration area.The disadvantage is that the analogy parameter system relies heavily on the main control elements of the resource accumulation.The resource triangulation method is the only method for the large area and dense sandstone gas,which is suitable for the large area and low exploration area.The disadvantage is that the calculation results are relatively rough and depend on the understanding of the resources discovery in the mature region.Finally,the difference of tight gas sands reservoir formation in North America and China is discussed,a proposal for evaluation process and parameter selection is put forward.