The Typical Low Permeability Reservior Description Study In Shiwu Oilifeld

Shiwu oilfield, is the deep reservoir in the central structural belt of Lishu fracture.Structures complex affected by the multi-phase tectonic movement. YingCheng formationforming a nearly north-south fault block and the North East nose structural traps by certainnearly east-west, north-south trending faults.Depth of1200to2200m, average thickness of840m, the average porosity of12.1%, average permeability8.7mD, is a low permeabilityreservoir. oilfield solution gas drive characteristics, is flexible solution gas drivereservoir.YingCheng-Sha Hezi formation accumulated submit the explored reserves1827.8×10~4t, oil area19.87km~2, controlled reserve1269.7×10~4t, oil area18.38km2.Based on previous studies, by the marker bed and combination well stratigraphic andseismic cross section, divided Yingcheng formation into four sand body, divided Shaheziformation into two sand body,and major petroliferous strata is divided into28sublayer.Through the multi-well stratigraphic demarcation, fine portrait of the Yingchengformation topsurface structural chart, theShahezi formation topsurface structural chart, Ying II,Ying III and Ying IV sand body topsurface structure, describe five structural chart.By coreobservation,establish the well facies and logging phase plates, analyzed sedimentarycharacteristics, and the microfacies model.Through core observation, SEM analysis, residualprimary pore, induced porosity and crack in study area, induced porosity is divided intointergranular pore, intragranular dissolution pores and dissolution corroded fissure.By castingthin slice, SEM, image analysis, the conventional pressure mercury technology andNMR,researched microscopic pore characteristics in Shiwu Oilfield Yingcheng-Shaheziformation, is divided into a hole thickness throat, smallhole in the throat, hole thin throat, porethin throat and fine pore throat five types.Established on the ultra-low permeability reservoirsShiwu oilfield reservoir evaluation and classification, divided Yingcheng-Shahezi formationreservoir into is theⅠ, II, IIIand non-permeability reservoirs, mainly III and non-permeabilityreservoirs.