Improving Recovery With Advanced Formation Evaluation And Well Placement Techniques In Thinly Laminated Sand-Shale Reservoirs

The industry today is drilling and evaluating increasingly complex and thinly laminated reservoirs to maximize recovery from existing assets. Consequently, reservoir management efforts aimed at maximizing production through optimal wellbore placement require increasingly sophisticated formation evaluation capabilities. In highly produced, thinly laminated sand-shale reservoirs, such as the Wilmington field, conventional resistivity sensors measure a high resistivity and fail to detect thin sand-shale sequences. Conventional interpretation shows low water saturation, misinterprets the net-to-gross ratio, and gives a very optimistic assessment of reserve in place. Formation evaluations in a thinly laminated sand-shale sequence seek to determine the sand and shale true resistivities and to provide an accurate estimate of reserve in place. This paper describes a new azimuthal resistivity sensor for advanced formation evaluation and well placement while drilling in the Wilmington field. It also explains the use of this new technology to plan and place the well in a thinly laminated sand-shale sequence of the Wilmington field. The paper also describes the advanced formation evaluation and well placement techniques based on this new azimuthal reading technology. Lessons learned, pitfalls, and best practices and challenges in this field are also discussed. Field examples are included to show the usefulness of this new technology during the evaluation and well placement process. Finally, reservoir cores confirmed that the high formation resistivity resulted from lamination of sand and shale and confirmed the effectiveness of the interpretation enabled by the new azimuthal reading technology