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

Microscopic characteristics of reservoir spaces of KT-I layer in the North Truva Oilfield. (a) Well 5555, 2335.24 m, residual foraminiferal micrite dolomite, visceral foramen and intercrystalline micropore; (b) Well A-2, 2887.88 m, sparry oolitic limestone, oolite moldic pore and intragranular dissolution pore; (c) Well A-7, 2669.76 m, silty dolomite, intercrystalline (dissolution) pore, residual dolomite crystal outline after dissolution, pores semi-filled by asphalt; (d) Well CT-4, 2341.66 m, bioclastic micrite dolomite, bead-like dissolution fissure, netted dissolution fissure, forming a fracture-cavity system with dissolved pores and caverns; (e) Well CT-22, 2299.93 m, sparry foraminiferal limestone, intergranular (dissolution) pores and visceral foramen; (f) Well 5555, 2345.72 m, residual bioclastic and silty-crystalline dolomite, intermittent extension of tectonic fracture, semi-filled by dolomite; (g) Well CT-22, 2300.55 m, foraminiferal fusulinid limestone, with vadose silt filling in the intergranular pores and granular cracks; (h) Well CT-59, 2383.09 m, collapsed karst breccia limestone in sharp angular shape, diverse structures and cluttered stacking patterns, with lime in the interbreccia pores and residual intergranular pores and shrinkage cracks.