Study of the Characteristics of Marine-Terrigenous Facies Shale from the Permo-Carboniferous System in the Guxian Block, Southwest Qinshui Basin

作者：Zhang, Miao; Fu, Xuehai^*

来源：Energy & Fuels, 2018, 32(2): 1096-1109.

DOI：10.1021/acs.energyfuels.7b02556

• NORTHEASTERN BRITISH-COLUMBIA
• MISSISSIPPIAN BARNETT SHALE
• GAS-ADSORPTION CAPACITY
• ORGANIC-RICH SHALES
• NORTH-CENTRAL TEXAS
• FORT-WORTH BASIN
• GEOLOGICAL CONTROLS
• THERMAL MATURITY
• PORE STRUCTURE
• METHANE ADSORPTION

This paper analyzes the characteristics of coal measure shale using samples from the Guxian Block of the southwest Qinshui Basin. Several methods, including X-ray diffraction (XRD), Rock-Eval pyrolysis, high-pressure mercury intrusion porosimetry (MIP), low-temperature nitrogen adsorption/desorption, and isothermal adsorption experiments, were used to investigate the organic geochemical characteristics, mineral composition, pore structure, and methane adsorption characteristics of the shales. Furthermore, the effect of the total organic carbon (TOC), thermal maturity, and mineral composition on the pore structure and methane adsorption capacity of shale was also investigated. The results showed that the TOC of the shale samples ranged from 0.19 to 31.66%, and the shale samples with TOC higher than 2% account for 31.17% of the total samples. The shale samples were in the high overmature stage with high hydrocarbon conversion rates. The mineral composition of the shale samples are mainly clay minerals and quartz, and the brittleness index calculated on the basis of mineral component is distributed primarily in the range from 40 to 50%, suggesting that the shale reservoirs have better fracturing properties. The mesopores were the major provider of pore volume, followed by macropores, and the micropores provided the least pore volume. The pores are open in style and mainly consist of cylindrical pores, parallel-plate slit pores, and bottleneck pores. TOC was the main controlling factor for the development of pores, followed by clay minerals. The pore specific volume created by organic matter was far greater than that of the clay minerals. Quartz arrested the development of pores, and the increase in the quartz content reduced the porosity by approximately 0.57-1.42%. As R-0 increased, the porosity first increased at the high-maturity stage and then decreased at the overmature stage. The maximum value appeared when R-0 = 2.0%. The TOC-normalized methane adsorption capacity decreased as R-0 increased. There was no obvious correlation between the clay mineral content and the TOC-normalized methane adsorption capacity, which may be atiributed to the shale water content. Vertically, as the sedimentary facies transited from carbonate tidal flat facies to delta facies, the porosity, Brunauer-Emmett-Teller (BET) specific surface area, Barrett-Joyner-Halenda (BJH) pore volume, and Langmuir volume generally decreased and the physical reservoir properties of the shale reservoir became weaker.

• 出版日期2018-2
• 单位中国矿业大学（北京）