Horizontal wells are being a common practice in offshore field development in Bohai Bay recently. Maintaining well trajectory in sweep spot while drilling is one of the key factors to optimize productivity of horizontal wells. To achieve this, great challenges are often faced in Bohai bay area including bias between the existing model and the actual, including microstructure and fluvial channels, sand-shale inter-bedding, strong permeability heterogeneities, complex special distribution of reservoir fluids (gas cap, bottom water or edge water) and relatively thin hydrocarbon pays. Therefore, the ability to update reservoir model in timely manner and to proactively adjust well trajectory in real time are required.

This paper presents a successful case in Bohai Bay by applying proactive well placement technology into an integrated approach to achieve very promising productivity than the initial prediction from two appraisal wells. This approach includes integrated reservoir study, operation optimization from drilling to completion, proactive well placement, real time interpretation, model updating and decision making. During integrated reservoir study, selected parameters and criteria to plan locations and trajectory of horizontal wells were derived from thorough rock physics and petrophysics studies. Detail geomechanical analysis was applied to optimize drilling and completion strategy. Proactive well placement technology - characterized by up to 15ft depth of investigation, directional measurements, 2D mapping of boundary/contact and 3D visualization was applied to optimize the placement of well trajectory in real time; which was also used to update reservoir model while drilling and close the gap between pre-drill existing model and real time interpretation. As the result, productions of the drilled two pilot horizontal wells are greatly exceeding the initial prediction. This proven approach can be applied to other planed wells in this field and other similar fields in Bohai Bay.

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