In heterogenic reservoirs such as carbonate reservoirs, bypassed oil or hydrocarbons is typically left somewhere in the reservoir. We can easily identify bypassed oil or hydrocarbon around low oil recovery wells (Figure 1). Typically, low oil recovery wells have low relative permeability to oil. Blue area in Figure 1 is the region of low oil recovery wells whereas green area is the region of high oil recovery wells. Strong signal is indicated in well 15 when well 27 is injected however the signal is weak or none in well 20 and 30. To develop blue area, more wells are required to recover all bypassed oil or hydrocarbon compared to green area. Drainage radius in green area could reach 300 m compared to blue area of 100 m. Blue area is more suitable developed by using horizontal wells or fracturing.
In current patent by Chevron, bypassed oil or hydrocarbon regions are identified by using permeability models and connectivity models. Those models are built for each production wells and injection wells. Both results from production and injection wells are combined to show long time of flight (TOF) regions which are identified as bypassed oil or hydrocarbon regions. The modeling and overlay are done by using computer and fast matching algorithm. The permeability data can be determined by core samples and well logs. Seismic data is also available for areal permeability modeling. The results of the modeling and overlay are drilling proposal for injection and production wells which are included horizontal wells.
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