OPTIMIZED HORIZONTAL WELLBORE PLACEMENT AND RESERVOIR CHARACTERIZATION WITH NEWEST LOGGING-WHILE-DRILLING TECHNOLOGIES

摘要

Real-time use of new and advanced LWD instruments during horizontal drilling gives us the opportunity to acquire high-quality well planning and reservoir information in a single run. Optimum interpretation from the real-time data acquisition enhances the planning and drilling of horizontal wells. This paper describes a well where the real-time information was extracted and included in the decision making process to an extent that sets a new industry standard. The bottom hole assembly used comprised not only the standard LWD services such as gamma ray, propagation resistivity, density, neutron porosity and LWD gamma ray and density imaging services, but also acoustic compressional and shear measurements, formation pressure testing while drilling and the newly introduced azimuthal propagation resistivity.To ensure a successful hydrocarbon producer on a marginal field with sparse information, we rely on the seismic interpretation, a geological model and a modicum of creativity. Verification or change of the geological model during drilling through comprehensive use of forward resistivity modeling and real-time geological interpretation, based on both the newly introduced azimuthal propagation resistivity service and resistivity from multiple depths of detection as well as wellbore images from both density and gamma ray, provide an enhanced basis for real-time well placement in horizontal drilling. The combination of horizontal interpretation of resistivity data, together with structural interpretation of image data, gives an improved understanding of the geology and aids in improving well placement. Upon integrating the realtime data interpretation with the seismic interpretation, the model is updated and improved during drilling to further aid the real-time wellbore placement. Application of LWD measurements enables accurate identification of the oil-water contact, gas-oil contact and top reservoir for a horizontal well through multiple branches drilled from one main bore in a continuous operation. The valuable information, obtained through controlled sidestep exploration drilling, provides additional information to optimize the producing main bore. Horizontal wellbore placement is supported by real-time reservoir characterization through real-time formation pressure measurement to validate any fluid movements and fluid compartmentalization of the reservoir. This paper describes a marginal field development in the North Sea where real-time data acquisition plays a significant part in the success of the field development and illustrates to what extent LWD data can help in optimizing well placement and reservoir characterization.