Transformation mechanism of muddy carbonate rock by the coupling of bioturbation and diagenesis: A case study of the Cretaceous of the Mesopotamia Basin in the Middle East

YE Yu,LI Fengfeng,SONG Xinmin,GUO Rui

Table 1 Reservoir characteristic parameters related to bioturbation in M oilfield.

Bioturbation intensity Infilling Percentage/% Dissolution Max pore-throat radius/μm Mean pore-throat radius/μm Mean values of physical properties Oiliness Porosity/% Permeability/10-3 μm2 Grade I Patched shape Calcite 8.3 No dissolution 0.20-1.06 0.37 0.04-0.08 0.05 6.5 0.06 Mainly oil trace, with fewer oil spots Dolomicrite 16.6 Fine-crystal dolomite 25.0 Mosaic dolomite 33.3 Syngenetic debris 16.6 Grade II Lamellar Calcite 8.7 No dissolution 0.23-2.32 2.74 0.06-0.94 0.23 11.5 2.44 Mainly oil spots Dolomicrite 4.3 Fine-crystal dolomite 60.9 Mosaic dolomite 13.0 Syngenetic debris 13.0 Grade III Mazy shape Calcite No dissolution 0.23-2.32 1.16 0.06-0.21 0.27 15.0 5.7 Mainly oil immersed and oil enrichment, locally oil spots Dolomicrite Fine-crystal dolomite 66.7 Mosaic dolomite Syngenetic debris 33.3 Grade IV Thick- layered shape Calcite 16.7 No dissolution 0.35-50.25 6.54 0.09-2.99 0.46 15.6 8.1 Mainly oil immersed and oil enrichment Dolomicrite Fine-crystal dolomite 70.0 Dissolution Mosaic dolomite 3.3 No dissolution Syngenetic debris 10.0 Dissolution