Effect of Burial History on Development of Deep and Ultra-Deep Clastic Rock Reservoirs: Lower Cretaceous Gaoquan Area, Sikeshu Sag, Southern Margin of Junggar Basin, China

The continuous breakthrough of deep and ultra-deep hydrocarbon exploration in China has attracted more and more attention. High-quality reservoir prediction is becoming one of the hotspots in deep and ultra-deep hydrocarbon exploration. Burial history, formation pressure and reservoir characteristics of the Qingshuihe Formation in the southern margin of Junggar Basin, China, were studied using thin section, scanning electron microscope, X-ray diffraction, stable isotopic testing of core samples, and homogenization temperature testing of fluid inclusion to explore the influence of burial history on the diagenetic process and reservoirs quality. Studies show that the Qingshuihe Formation went through four stages of the burial process after deposition, which successively consists of a long-term shallow burial stage, tectonic uplift stage, normal continuous deep burial stage and short-term rapid deep burial stage. The early long-term shallow burial and tectonic uplift stages not only can alleviate the strength of compaction, but also can maintain an open geochemical system in the reservoirs for a long time, which promotes the dissolution of intergranular volcanic ash by meteoric freshwater leaching and provide more secondary dissolution pores. The late short-term rapid deep burial process contributed to the development of overpressure, which effectively inhibits the destruction of primary pores resulted from compaction. Moreover, overpressure promotes the development of microfractures in the reservoirs, which can improve the permeability of the reservoirs and enhance the dissolution effect of organic acid. This study clarified the effect of burial style on the development of high-quality reservoirs by revealing the influence of burial process on diagenesis such as compaction, cementation and dissolution. It deepens the understanding of the development law of deep and ultra-deep high-quality clastic rock reservoirs, and also provides a new idea for the prediction of deep high-quality clastic rock reservoirs.