Characterization of marine-terrigenous transitional Taiyuan formation shale reservoirs in Hedong coal field, China

[摘要] To better understand the basic characteristics of Marine-terrigenous Transitional Taiyuan formation shale (TYS) reservoirs in Hedong coal field, a series of reservoir evaluation experiments were conducted on 33 core samples, which were collected from an exploration shale gas well (SL-1). The results show that organic matters in TYS are Type III gas prone kerogen and are in the high-maturity stage with an average Ro value of 1.87% (ranging from 1.71% to 2.10%). The total organic carbon (TOC) is ranging from 0.29% to 11.87% with an average value of 2.91% and gas content is from 0.41% to 2.96 ml/g, which indicates that TYS still has certain hydrocarbon generation potential despite a mass generation of hydrocarbons occurred during the geological history. X-ray diffraction analysis shows that TYS is composed mainly of quartz minerals and clay minerals with an average brittleness index of 46.5%, which is relatively favorable for hydraulic fracture. Pore size of TYS ranges from a few nanometers to hundreds of nanometers. The permeability is irrelevant with porosity and its values are all lower than 0.1 md. The average value of Brunauer- Emmett-Teller surface area and Barrett-Joyner-Halendar volumes are 8.57 m 2 /g and 1.84 cm 3 /100g, respectively. Similar to previous studies, TOC content is a decisive control on gas adsorption capacity in this study.

[关键词] Marine-terrigenous transitional shale;Ordos basin;Hedong coal field;formation