An integrated approach to unconventional resource play reservoir characterization, Thistleton-1 case study, NW England

Scott Brindle, David O’Connor, Richard Windmill, Peter Wellsbury, Guy Oliver, Graham Spence and Chi V. Ly characterize a UK unconventional reservoir using integrated AM and TOC data to constrain and improve the accuracy of petrophysical modelling. In the past, the oil and gas industry considered hydrocarbon resources locked in tight, impermeable formations like shale uneconomical to produce. However, advances in well steering, drilling and reservoir stimulation techniques have dramatically changed this perspective. Unconventional shale reservoirs have low permeability and cannot produce economically without effective placement of horizontal laterals and effective hydraulic stimulation. To achieve this, it is critical to recognize brittle units responsive to hydraulic fracturing and rich in organic matter. Shale mineralogy impacts the effectiveness of stimulation. Heterogeneity in shale reservoirs expressed by mineral composition, richness of organic matter and brittleness significantly influences shale gas production. In these reservoirs, the occurrence of clays is a significant risk to production and it is a major challenge to be able to locate and quantify them. The industry reported $7bn of unnecessary costs due to unconventional wells not reaching their production targets (Welling and Company, 2012). Moreover, 15-20% of all fracture stages are reported as ineffective while 35-40% of perforation clusters do not contribute to production (Hodenfield, 2012) highlighting a need for more low-cost and low-risk data. This data could help to improve completion designs to achieve more consistent production from all stages and increase the overall profitability.