ICE 2022


Significant investments have been made to evaluate shale gas & condensate potential within the Jafurah Basin of Saudi Arabia. The main drilling target is the Middle Jurassic Tuwaiq Mountain formation, calcitic and TOC-enriched mudstones deposited in depositional lows of the carbonate-prone Arabian plate. The Jafurah Basin was later deeply buried during the closing of the Tethyan Sea, and horizontal drilling targets are now mostly within the gas and condensate window. Published research indicates that multiple drilling and completions strategies have been attempted here, but optimal development design has not yet been achieved. To aid in Jafurah shale development optimization, the Late Cretaceous Eagle Ford formation of Texas was chosen as a “res-frack analog” because of comparable lithology, depth of burial, pressure and an abundance of drilling and completions data. Hundreds of drilling, completion and geologic variables were run through a gradient boosting machine learning model, which enabled identification of a smaller subset of variables most impacted productivity and economics. Play-wide results indicate spacing decisions had the largest impact on oil productivity, whereas gas production was more impacted by geologic variation. Focusing on post-2016 completion variables from study area wells, our results show that of the six operators in the region, ConocoPhillips and Devon have hydrocarbon recoveries and half-cycle NPVs closest to optimal. Our modeling indicates that the bottom two-thirds of operators have potentially left 21-32% of optimal recoveries and $908MM of NPV across 475 wells. Because Jafurah horizontal wells have targeted gas- and condensate-prone carbonate mudstones, a subset of high carbonate, gas/condensate Eagle Ford wells were further analyzed. The Lower Eagle Ford was isolated for this study, and spacing calculations were performed utilizing an average radial distance for all zones. Results indicate that hybrid fracturing jobs outperformed slickwater fluid design on NPV per well and per section metrics. Optimal proppant-to-fluid ratios and well spacing was exemplified by ConocoPhillips relative to other operators. These insights from the Eagle Ford can be leveraged to rapidly optimize drilling and completion strategies in the Jafurah Basin. Furthermore, this study illustrates how North American unconventional reservoirs will be key “res-frack analogs” that can help unlock potential from other international shale plays.