Accumulation Pattern And Producibility Of Yingxiongling Shale Oil,Qaidam Basin

In recent years,China’s multi-point strategic breakthroughs in marine shale gas and continental shale oil have become the most realistic strategic replacement resources for future oil and gas storage and production.In 2021,Chai Ping 1 well in the Qaidam Basin broke 100 tonnes of oil in the test and made a strategic breakthrough in Yingxiongling shale oil exploration,which is one of the most important and realistic fields for Qinghai Oilfield to increase reserves and production in the future,and an important resource base for the construction of a new highland of ten million tonnes of comprehensive energy.The special depositional environment and complex evolutionary process of the Yingxiongling shale have led to several challenges in the current exploration and development.The low organic matter abundance hydrocarbon source rocks have unclear hydrocarbon generation capacity,which restricts the understanding of hydrocarbon resource potentials;the complex sedimentary and tectonic evolutionary processes have resulted in a high degree of non-homogeneity in the spatial distribution of resources and difficulties in selecting sweet spots/sections;the complexity of factors controlling shale oil flow and output,and lack of an effective development technology policy;traditional oil and gas exploration and development project operation mechanism is facing challenges in four aspects:technology,cost,management and concept,and it is difficult to meet the demand for the development of unconventional oil and gas scale efficiency.This paper focuses on the accumulation pattern and producibility of the Yingxiongling shale oil in response to the aforementioned challenges,and conducts systematic research and technical breakthroughs:（1）Aiming at the mismatch between relatively low organic matter abundance and large-scale oil and gas discovery,through organic-inorganic geochemical experimental analyses and technological innovations in simulation,this paper have elucidated the type of hydrocarbon generating parent material and the conditions of organic matter enrichment and preservation in the Yingxiongling Shale,revealed the reasons for low organic matter abundance,and clarified the mechanism of the two-stage high-efficiency hydrocarbon generation of carbon-poor,hydrogen-rich organic matter,so as to lay down a resource foundation for the formation of large-scale hydrocarbon aggregation in the hydrocarbon source rock with low organic matter abundance.Applying the new hydrocarbon production model,the preliminary estimation of the oil production of Chaixi depression shale is 1063×10⁸t,and the implementation of the favourable exploration area of Yingxiongling shale oil is nearly 3,000 km²,with the resources exceeding 40×10⁸t.（2）Aiming at the problems of strong non-homogeneity in the spatial distribution of shale oil resources in the Yingxiongling,unclear enrichment mechanism,and difficulty in selecting sweet spot areas/sections,thia paper carried out research on tectonic evolution,stratigraphic stratigraphy,sedimentary phase analysis,and construction of the formation and storage model,and clarified the characteristics of the"four qualities"of shale oil in the Yingxiongling,put forward the indicators of the key parameters of the depth of burial,tectonic modification intensity,layer/stripe ratio,and the content of free hydrocarbons（S₁）,and set up the criteria for evaluating the sweet spot of giant-thick,mountainous-type shale oil;and constructed the models of the four categories of shale oil sweet spot enrichment and well development and release for the stratigraphically controlled type,stratigraphically controlled-seam controlled composite type,fracture-controlled type,and salt-controlled type.（3）Aiming at the problems of poor understanding of the flow and output laws of Yingxiongling shale oil and the failure to establish efficient mobilisation methods,this paper innovated and combined micro-characterisation techniques such as identification of shale oil endowment state,quantitative analysis of oil content and evaluation of movable oil saturation with macro-evaluation techniques such as quantitative analysis of compressibility and evaluation of crude oil output under the action of fluids,elucidated the connotations and logical relations between the"micro-static mobility"and the"macro-dynamic producibility"of shale oil,clarified the mechanism of the influence of the nature of the fluids under the control of the type of petrographic phase,the nature of the oil-water interface and the modifiability of the output of crude oil,and put forward the key development technological countermeasures to enhance the producibility of the Yingxiongling shale oil.（4）Aiming at the reality that the operation mechanism of traditional oil and gas exploration and development projects is difficult to meet the demand for the development of scale efficiency of unconventional oil and gas,based on the core concept that shale oil beneficial development must be driven by"technology+management"and a large number of cases of exploration and development engineering practice,the"one engine and six gears"methodology is proposed,an optimized model for the entire life cycle of unconventional oil and gas development is established,and four well deployment methods and development models for the Yingxiongling shale oil are formulated.