Diagenetic evolution recorded from the fractured carbonates of Trang Kenh formation, in the north-eastern area of Vietnam

Tóm tắt

Diagenetic evolution makes a signifi cant contribution to the quality of carbonate reservoir. A detailed geological work was undertaken in a quarry outcrop in Hai Phong city, in the North-Eastern area of Vietnam as the fi rst step in better understanding and gaining an insight into the complex diagenetic evolution of carbonate play. This work integrates the results of detailed mapping and interpretation of lithologies and fracture orientations, along with detailed petrographic and isotopic analyses. Across the units exposed in the studied quarry, textures and isotopic signatures remaining in the out crop, illustrate the diagenetic history of three substages of diagenetic processes (eogenetic, mesogenetic and telogenetic) that has driven both poroperm reduction and enhancement. Only the most recent overprint has enhanced the poroperm via secondary poroperm features, such as vugs, solution-enlarged fractures (vuggy fractures), channels, and cavernous porosity, generated by a combination of uplift and meteoric mixing dissolution. Signifi cant levels of poroperm in fractured Devonian carbonates in the region are predominant by NE-SW fracture sets that are created and enlarged in the telogenetic realm. Equivalents to the most important telogenetic substage, recorded in outcrop, likely occur in off shore Devonian subsurface carbonate reservoirs.