The Role of Production Logging in Optimizing Unconventional Shale Gas Stimulation in Middle East

Abstract

Abstract Most unconventional shale gas reservoirs are being produced through a series of hydraulically fractured stages distributed across horizontal wells. Different fracturing techniques are being used to maximize well performance in a most feasible manner. Some techniques may economically present more advantages than others. The study outlines a workflow on how to select the right diagnostic tools, plan and design the logging intervention putting different well conditions in perspective such as variations in production rates, slugging, water recirculation, water loading and nitrogen (N2) lifting. The workflow also includes the critical steps needed during data acquisition and interpretation to provide a more accurate evaluation. This paper illustrates two case studies. The first case discusses a horizontal shale gas well in the region that was completed with 12 fracturing stages. The second case was completed with 14 stages. Different fracturing techniques were utilized to maximize the production and the optimal hydraulic fracture design was investigated in terms of well productivity. The multi-spinner production log was combined with the pulsed neutron log (PNL) and water flow log (WFL) in one of the wells to determine the downhole flow profile along with accurate water entries due to different trajectories and low water rates. Zonal gas and water flow production were obtained for each fracturing stage despite challenging well deviation and complex gas-water flow regimes. Pressure buildup data acquired simultaneously with the multi-spinner production log in an efficient manner led to more accurate reservoir pressure. Stages with water production were shut off successfully, reducing the water rate accordingly. These results were incorporated with the early fracturing data for a better understanding of the well performance and also to optimize the completion and fracturing design for future wells to be drilled in the same field.