Research and Practice on Well Pattern Technology for Combined Flooding and Gravity Drainage in Offshore Extra-Heavy Oil Reservoirs with Thick Layers

Le résumé fourni par la source

Abstract Aiming at the core challenges of severe steam override and poor vertical reserve utilization efficiency in the development of offshore thick-layer extra-heavy oil reservoirs, this study has carried out research on the optimal design of flooding-drainage combined well patterns. First, physical simulation experiments of cyclic steam stimulation conversion to flooding under different three-dimensional well patterns were conducted to analyze the correlation between production performance and injected pore volumes (PV), quantify the expansion rate of heating chambers, and divide production stages. Meanwhile, the development characteristics of temperature fields and steam chamber sweep efficiency were investigated. Combined with rheological experiments on oil samples from the target oilfield, the dynamic changes of pseudo-threshold pressure gradient during cyclic steam stimulation were quantitatively analyzed, and its correlation with fluidity and temperature was regressed. Furthermore, a calculation method for vertical threshold pressure gradient was established via numerical simulation, and the vertical utilization boundary of steam cyclic steam stimulation wells was determined. Finally, based on the results of physical and numerical simulations, a novel flooding-drainage combined well pattern for thick-layer extra-heavy oil reservoirs was proposed, which balances the expansion of steam flooding areal sweep and gravity-assisted drainage. The results show that staggered vertical well deployment can synergize steam flooding and gravity drainage, significantly improving the vertical sweep range and reserve utilization efficiency of thick-layer heavy oil. Optimizing vertical well placement based on the threshold pressure gradient model can effectively ensure inter-well pressure communication and efficient reservoir utilization. The established well pattern spacing design method and the new well pattern provide a key technical approach for the efficient development of offshore thick-layer extra-heavy oil reservoirs.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.