Innovative Integration of Seismic and Reservoir Simulation Modeling with Drilling and LWD Measurements to Manage Development Risk in Complex Channel Reservoirs—Opening Opportunities to Redevelop Mature Field in Bohai Bay, China
Authors: Bie Xuwei , Yang Qinghong , Liao Xinwu , Nie Chaomin , Hu Yong , Thanh Tran , Hao Cheng , Lin Wen , Halomoan Parlindungan Monris , Xu Chong Hui 
Published: October 2014

The Qin Huang Dao 32-6 (QHD 32-6) mature oil field is located in Bohai Bay, China. The field has cumulative oil production of 135 million barrels, produced by 174 production and 28 injector wells. A redevelopment project with four new platforms and 101 wells—88 horizontal wells and 13 directional high-angle wells—in five major reservoirs was initiated in late 2010 with the objective to recover an additional 98 million barrels of original oil in place (OOIP) by Year 2035.

The redevelopment and exploitation of these targets present complex operational challenges. Uncertainties that may have significant impact on prospect definition and field redevelopment execution are associated with the complex subsurface environment of soft, unconsolidated, fluvial channel sand reservoirs, with the maturity of a heavy oil field with uncertain natural aquifer or injected water sweep, and with well surveys and well depth control. Not only must a planned horizontal well be optimally placed within the complex channel sand facies, which dramatically changes vertically and laterally across the field, but because of the high viscosity and low gravity of the heavy oil, which has a much lower mobility than the water, the horizontal well must be placed in the good-quality reservoir zone underlying the siltstone zone while also keeping the well away from the unknown current fluid contact.

To reduce the uncertainties and ensure the optimal placement of the well in the best position to drain the remaining hydrocarbons, we have implemented the combined integration of multimethod-processed seismic data and reservoir simulation models with a rotary steerable drilling system and logging-while-drilling (LWD) azimuthal deep directional electromagnetic-based measurements.

The seismic data and reservoir simulations highlight both structural and sedimentary features in the macro scale. These simulations are used as the reference for reservoir target selection, well planning, and well execution. The azimuthal LWD data highlight the reservoir at the micro scale, with the ability to map the lithologic boundaries and fluid contacts in distance. The rotary steerable drilling system provides accurate well control while maneuvering in soft and unconsolidated sands. Data from both logging and drilling systems are used during well execution in addition to the seismic and reservoir simulation data.

On the basis of multiple well field studies discussed in this paper, the team has observed that the integrated application has helped to Identify optimal reservoir target location selection and well planningIdentify geobodies of the complex channel sand facies and their interfaces with accuracyIdentify the current fluid contactsIdentify the best position to drain the hydrocarbonsReduce overall subsurface-associated risks.

Finally, the authors conclude that by facilitating seismic and reservoir simulation of the macro system in combination with the accuracy and efficiency of drilling and LWD measurements in the micro system with respect to geology and reservoir engineering, the redevelopment of the mature field can be optimally planned and executed with the eminent potential for further improvement of the field recovery factor, yielding a significant economic value.