Sedimentary Facies And Oil Accumulation Of M1 Sand-stone Reservoir In The Tarapora Block Of The Oriente Basin

This thesis focuses on the M1 sandstone reservoir in Johanna-East Alice-West oilfields within the T-block of the Oriente Basin,for the purpose of promoting oil production.There have been high amounts of water produced from the reservoir,and there are two major problems which need solving:(1)Based on previous studies,there are two interpretations of the sedimentary environment,Tidal control Delta and tidal control Estuary.However,to deepen the understanding of the area,the specific sedimentary microfacies must be determined,and defined what affects the distribution of good reservoir-(2)There needs to be a better understanding of the major factors that control the oil distribution within the reservoir.This requires understanding the interlayers,and the distribution and prediction of favourable sand body.The objective of the research aims at gaining a better understanding of the sedimentary facies and related control on oil accumulation in this study area which may help improve the overall production of petroleum.To achieve the intended objectives,the research incorporated 3D seismic data,well logging data and core data,all of which were provided by the Andian company for the purpose of research.This seismic data covering the study allow for the application of stratigraphic concepts to the subsurface where seismic parameters such as internal velocity,frequency,amplitude,continuity,and reflection configuration were used to define sequence division and sedimentary recognition,while the well logging data such as Gama ray logs,Neutron logs,resistivity logs,Density and Sonic logs are used to interpret lithology,depositional environment and depositional sequences.Core data was then used in the research,with two cores(Al-W＿09 core,and Jo-E＿45)retrieved by the drilling of two wells in the Alice West and Johanna＿East oil fields.These cores were retrieved from depths within the M1 SS Sandstone reservoir,which were analysed for lithological change,structure,organism,physical properties,and electric properties.Research showed that the M1 reservoir can be divided into three sublayers with the top and bottom mudstone layers of M1 SS identified as the main marker layer sequence using core and well logging data.Sedimentary facies of the M1 SS are classified as tidal-controlled estuary sediments,mainly characterised by its fining upward vertical stacking pattern probably due to seal level rise,which is different from delta environment which is often featured by a coursing upward stacking pattern caused by sea level fall.The microfacies of tidal-controlled estuary are subdivided into tidal sand bars,tidal sand flats,and mixed flats.Based on the plane-view maps we propose the provenance of the sediments deposited in the study area is from the southeast.Physical property analysis data show that the M1 SS layer is mainly sandstone with high porosity and permeability,good roundness and sorting properties.Structural units in the study area are very limited,and the oil accumulation and distribution are largely controlled by the distribution of favourable reservoir bodies and mudstone walls which impedes connectivity and flowability.Therefore,we propose reservoir sandstone are the key factor controlling the oil accumulation in the study area.Generally,the understanding of the sedimentary facies distribution and its role in oil accumulation may help the future oil production activities in the study area.