A Study On Reservoir Description And Geological Modeling Of Tide Dominated Estuary In J Oilfield,Oriente Basin

At present,domestic and foreign experts have less research data on the sedimentary characteristics of the tide dominated estuary.The tide dominated estuary is mainly formed at the transgressive sedimentary environment,the sedimentary characteristics are very complex.Study area is the J oil field in the T block of the Oriente Basin in South America,the whole area is characterized by the tide-controlled estuarine sedimentary characteristics.The research layer is the M1SS sandstone reservoir.In order to clarify the reservoir characteristics of the study area,we have carried out regional stratigraphic framework,sedimentary microfacies feature analysis,sedimentary dynamics simulation and fine 3D reservoir modeling.The characteristics of the interface of the layers in the tidal-controlled estuary are mainly characterized by the scouring surface at the bottom of the diversion channel,the vertical structural transition surface of the rock type and rock association,and the variation of the thickness of the argillaceous sandstone.In the characteristics of the logging curve,the main difference is that the combination pattern of the numerical value of the natural gamma(GR)curve and the log curve changes significantly.According to the stratigraphic classification,the M1SS reservoir is divided into three small layers of M1SS-1,M1SS-2 and M1SS-3.The M1SS is a positive rhythmic feature with a fine grain size.However,within the three sub-layers of M1SS-1,M1SS-2 and M1SS-3,the log shape mainly reflects the variation of vertical accumulation.The study area is located in the tide dominated estuary,and the sedimentary microfacies are mainly developed as the tidal sand bar,the tidal sand flat and the thin muddy layer.The sand bar is contiguous in the interior of the work area and is elongated along the source direction.At the edge of the sand dam the thin argillaceous sandstone is deposited.According to the Petrel model,the location of the high porosity and the high permeability in the study area is consistent with the distribution position of the sand dam.Using Dionisos to simulate the deposition process of the whole study area,it is found that the distribution of the sand body in the tidal-controlled estuary is controlled by the water flow intensity and the source supply rate.The stronger the water flow,the higher the riverization degree,the worse the sand body continuity.The distribution of the interlayer distribution is more dispersed.The vertical distribution is controlled by sea level rise and fall and structural settlement,and the space change can control the cyclicity of sand and mudstone distribution.Getting variable distance parameter of lithology modelling from the sedimentation dynamics results.Creating the Petrel 3D reservoir model with the combination of the sedimentation dynamics results,sedimentary facies characteristics and Sedimentary facies characteristics.The Petrel model include lithology model,porosity model,permeability model and saturation model.As the model showing,the property of this reservoir is fine.The average porosity of J oilfield is 17.56%,the average permeability of J oilfield is 2.78D and the average saturation is 56%.According to the 3D model,reserve uncertainty analysis is carried out.The high reserve of J oilfield is 50×10~6t,the low reserve is 38×10~6 t and the average is 45.49×10~6 t.