Pore-throat structure characteristics and its impact on the porosity and permeability relationship of Carboniferous carbonate reservoirs in eastern edge of Pre-Caspian Basin

LI Weiqiang,MU Longxin,ZHAO Lun,LI Jianxin,WANG Shuqin,FAN Zifei,SHAO Dali,LI Changhai,SHAN Fachao,ZHAO Wenqi,SUN Meng

Table 1 Characteristics of different types of reservoirs in the Carboniferous KT-I layer, North Truva Oilfield.

Reservoir type Main lithology Core FMI Thin section Poro- sity/% Permea- bility/ 10-3 μm2 Average pore throat radius/μm Sorting coeffi- cient Efficiency of mercury withdrawal/% Pore-cavity-fracture type Silty dolomite, silty-micritic dolomite, micritic dolomite and grain dolomite 5555, 2 331.16 m CT-11, 2 341-2 343 m CT-4, 2 341.66 m 7.40- 25.70 (16) 0.93- 349.00 (54.6) 0.56- 11.10 (3.27) 1.72-3.87 (2.53) 15.50- 74.10 (37.4) Pore-cavity type Micrite, silty-micritic dolomite and biologic grain limestone CT-22, 2 350.45 m CT-65, 2 727-2 729 m CT-59, 2 423 m 26.70- 38.40 (30.6) 9.94- 230.00 (103.2) 0.68-6.03 (2.78) 1.59-2.54 (2.06) 30.30- 66.60 (52.7) Pore-fracture type Grain limestone, silty dolomite, karst breccia limestone CT-10, 2 350.58 m CT-10, 2 346-2 348 m 5555, 2 345.72 m 1.18- 25.40 (6.34) 0.01- 27.60 (3.71) 0.01- 10.20 (1.31) 0.96-3.86 (1.85) 11.20- 62.50 (29.6) Pore type Foraminiferal limestone, calcarenite, micritic dolomite CT-10, 2 388.19 m CT-1, 2 366-2 368 m CT-22, 2 299.93 m 4.50- 20.80 (11.1) 0.01-8.16 (0.74) 0.03- 10.30 (2.17) 1.09-3.34 (1.96) 2.35- 57.70 (27.6)