Genetic mechanism of high-quality reservoirs in Permian tight fan delta conglomerates at the northwestern margin of the Junggar Basin, northwestern China

• DOI: 10.1306/02071715214
• Publication Date: 2017-12-05T18:34:09Z
• Authors: Guanghui Yuan; Yingchang Cao; Longwei Qiu; Zhonghong Chen
• Keywords: Margin (machine learning)

Fan delta conglomerate reservoirs in the Permian Jiamuhe Formation Zhongguai area at northwestern margin of Junggar Basin, China, are for large accumulations natural tight gas. The conglomerates and sandstones mainly litharenites with a amount texturally compositionally immature volcanic clastic materials. Core porosities demonstrate development anomalously high depths 3200–4200 m (10,500–13,800 ft) 4500–4900 (14,800–16,100 ft). experienced initial rapid subsidence, uplift, further diagenetic reactions occurred these involving compaction; precipitation chlorite clays, calcites, zeolites, iron oxides, kaolinite, quartz cements; dissolution unstable minerals including analcite, laumontite, feldspars, rock fragments. Low-porosity reservoirs, extensive compaction (or) cementation calcite heulandite-Ca, consist only few visible secondary pores formed by feldspars Reservoirs porosity, however, relatively weak contain significant amounts laumontites, some Comprehensive studies sedimentary features diagenesis indicate that originate from chronological coupling four important geological processes. (1) Sedimentary facies detrital compositions controlled distribution various zeolites abundant laumonites developed fan front subfacies. (2) Early laumontites inhibited during deep burial; they provided porosity development. (3) subaerial exposure erosion uplift stage, meteoric freshwater leached laumontite cements aluminosilicate grains to form beneath unconformity. (4) Hydrocarbon emplacement relative shallow depth second subsidence period preserved retarding late carbonate cementation.