Oil Displacement Simulation Experiment With Different Matching Modes Of High-Quality Subfacies Sand Body In Delta Front

The Xingbei X block of Daqing Oilfield has entered a high water cut period.The class?and class ? oil layers are highly flooded,but there are still large oil and gas reserves in the untabulated reservoir of the class ? oil layers that have not been effectively utilized.Therefore,strengthening the research on the utilization characteristics of untabulated reservoir can provide a theoretical basis and practical basis for the accurate and efficient potential tapping of oilfields and the economic and effective utilization of remaining reserves.In this article,taking the II oil group of Saertu oil layer(hereinafter referred to as SII oil group)in Xingbei X area of Daqing oilfield as an example,guided by high-resolution sequence stratigraphy and fine sedimentology theory,using fine-contrast technology of river delta strata,the SII oil group is divided and compared with the sedimentary time unit level,and the fine isochronous stratigraphic framework of the SII oil group is established.On this basis,combined with previous research results,it is determined that the SII oil group in the study area mainly develops delta front subfacies,which can identify four types of sedimentary microfacies such as underwater distributary channel,underwater shunt room,estuary bar,and sheet sand.In order to construct the development model of the untabulated reservoir,the estuary bar is further divided into three types of energy phase units: first-class estuary bar,second-class estuary bar,and dam margin.The sheet sand is divided into two types of energy phase units: first-class sheet sand and second-class sheet sand.Among them,the main types of energy phases constituting the untabulated reservoir are first-class estuary bar,second-class estuary bar,first-class sheet sand,and second-class sheet sand.The relatively high-quality sand bodies in the off-surface reservoirs are mainly the effective sandstone on the top of the first-class estuary bar,the second-class estuary bar,and the middle effective sandstone section of the first-class sheet sand.There are various plane contact relationships and vertical combination patterns between the high-quality sand bodies in the untabulated reservoir and the conventional untabulated sand bodie.In this study,we focused on extracting the five common wellbore sand matching modes in oilfield for oil displacement simulation,namely:conventional untabulated sand body and high quality sand body parallel mining mode,conventional untabulated sand body is in parallel with high-quality sand body and conventional untabulated sand body perforated mining mode,conventional untabulated sandbody independent mining mode,conventional untabulated sand bodies and high-quality sand bodies cascade mining mode,conventional untabulated sand body connected with the spiky high-quality sand body mining mode.Simulation experiment results show that,conventional untabulated sand body and high quality sand body parallel mining mode is affected by the permeability range,and high-quality sand bodies are preferentially used,resulting in good use of high-quality sand bodies,poor conventional untabulated reservoir use,and a laminar flow state inside the core;conventional untabulated sand body is in parallel with high-quality sand body and conventional untabulated sand body perforated mining mode is affected by the permeability range,and the fluid flows from the perforated conventional untabulated sand body parts to the high-quality sand body parts,resulting in good use of high-quality sand bodies,the conventional untabulated reservoir oil is poorly used,and the fluid inside the core presents a turbulent state;conventional untabulated sand body independent mining mode is affected by the homogeneity and low permeability of the conventional untabulated sand body,the conventional untabulated sand body has the lowest utilization degree,and the displacement fluid is in a laminar state inside the core;conventional untabulated sand bodies and high-quality sand bodies cascade mining mode is affected by the homogeneity of the sand bodies,and the displacement fluid moves horizontally from the high-quality sand body to the conventional untabulated sand body,the high-quality sand body is preferentially and well used,and the conventional untabulated is poorly used;conventional untabulated sand body connected with the spiky high-quality sand body mining mode is affected by the permeability range and the pressure difference between the injection and production,the fluid flow in the core is in a turbulent state,flowing from the perforation to the high-quality sand body,and the conventional untabulated is poorly used.