Glutenite Sedimentary Pattern under the Control of Contemporaneous Reverse Thrust and Favorable Reservoir Facies Belt Distribution-Taking P₃w, B25 Block, Mahu sag, as an example

Key words: 
• south slope in Mahu sag /
• P₃w /
• alluvial fan /
• fan delta /
• contemporaneous reverse fault /
• shale content /
• crush seam

Abstract: Based on the analysis of core facies, logging facies, seismic facies and analysis assay data, with the field practice induction of glutenite sedimentary,this paper draw conclusions that:Fan-fan delta glutenite sedimentary system under the control of contemporaneous reverse thrust show the progradation deposition on the whole in P₃w. Indicating the phase-sequence characteristics called "Alluvial fan toe (channel flow)-Alluvial fan middle/Fan delta plain (braided stream)-Fan delta front(distributary belt)-former fan delta/shallow lake (be mixed up with subaqueous fan)".with the development of such five typical glutenite sedimentary microfacies types as channel flow, debris flow/sandy debris flow, braided channel, underwater distributary channel, sectoral waterway. The cumulative effect of contemporaneous reverse fault belt continuous uplifting and denudation, make the sedimentary of fan toe in alluvial fan thinning, with more and more obvious trend of contemporaneous reverse fault controlling the sedimentary facies differentiation. Shale content is the key control factors of glutenite reservoir quality under the extrusion background. The diagenetic compaction cut hole effect in poor mud glutenite reservoir is weak, with the higher residual intergranular pore development and the higher development level of crush seam in coarse particles communicating intergranular pore, the reservoir quality of poor mud glutenite is best. Based on combination of reservoir space,the favorable reservoir facies belt can be divided into two types:primary intergranular pore-crush seam development zones and primary intergranular pore-secondary dissolution pore development zones. The former mainly distributed in the fault zone-upper slope belt near structural high position, the latter mainly distributed in middle-lower slope belt.