Open hole logging of highly deviated and horizontal wells is now becoming more accepted due to a recently developed conveyance and acquisition system that can greatly reduce the cost and risk associated with running logs in these types of wells. Conventional log measurements including resistivity and porosity, which in many cases may not have been previously economical to obtain in lateral wells, can now be used to delineate the needed basic reservoir properties for planning completions and future drilling designs.
The method employs a newly engineered ultra slim toolstring that is designed to pass through the drill pipe and a specially designed hollow PDC bit into open hole. Data can then be obtained beyond the bit in memory while tripping out with the tools on pipe. Lost in hole risk and the higher cost of using other more expensive methods, such as LWD, can be minimized by using the drill pipe and bit to safely acquire the data and retrieve the tools if necessary. Circulation of the well fluids and pressure control can still be maintained throughout this process. A brief overview of the conveyance method and acquisition tools will be presented along with log examples from some of the common unconventional plays that outline the applications of this data.