Completion and Multi-Stage Infill Frac Methodology to Unlocks the Potential of Tight Oil Reservoir

Abstract An oil field in Southern Oman, producing from a tight, sour salicylate reservoir, faces a steep production decline after 24 years on stream. Maximizing recovery from the 300-meter pay requires infill selective slickwater stimulation. However, isolating existing perforations using mechanical completions is cost-prohibitive and operationally complex, limiting high-rate treatments. This paper presents a successful chemical diversion fracturing strategy, enabling controlled fracture propagation across closely spaced zones, combined with a high-viscosity friction reducer (HVFR) based on high salinity water trial to optimize placement, efficiency and ultimately to keep the project within the initial budget. A gas injector was treated in November 2024. The pay zone at 4,100 mMD had four existing perforations intervals below. Four-stage fracturing stimulated the top 80 m pay zone. Completion strategy on Stage 2 (perforations at 4,067-4,070 m and 4,056-4,059 m), where chemical diversion technique was employed to place two sequential fracture treatments (2a and 2b). Stage 2a was pumped with 54 metric tons (MT) of proppant, followed by pumped chemical diverter, and then Stage 2b with 76 MT of proppant. High-rate pumping of up to 8 m3/min tested the limits of the diverter's effectiveness, maximizing the stimulated rock volume and assessing its ability to maintain zonal isolation. DFIT and radioactive tracer were conducted to verify geomechanics and diversion efficiency. Accessible fresh water logistic related cost can reach six digits but a new HVFR frac fluid tolerant to high salinity water deployed on Stages 2a, 2b and 3 enhanced operation efficiency and reduced total operating cost. Pressure trends and post-treatment tracer logs confirmed successful diversion. With Stage 2a fractures propagating through both 2a and 2b perforations, while Stage 2b fractures exhibited clear isolation from the lower section. These results validated the initial breakdown test data, highlighting the chemical diverter efficiency. Selectively placed fractures in a high-stress, low- permeability laminated formation met the objective. The new HVFR frac fluid demonstrated successful application with high-salinity water, proving its viability as an alternative to fresh water. Total operating cost was reduced by 25% with application of chemical diverter and New HVFR fluid system.