Lowering the Uncertainties with Innovative Practices for Enhancing the Performance Evaluation of Ultra-Sour Tight Reservoirs

Abstract Exploration of new zones has always carried risks and uncertainties because of the limited geological data of the reservoirs and potential for hydrocarbons. In the study of an unconventional reservoir through several vertical pilots, with minimum horizontal stresses between 8600 & 10000 psi (0.86 – 1 psi/ft) and permeabilities around 1 md, innovative methods were tested to establish and determine the productivity/injectivity in the high stress sections. Such techniques included Advanced perforation systems, and advanced stimulations with customized fluids and specialized Coil Tubing (CT) tools, all of them constrained by the surface and subsurface equipment capacities to maintain integrity. The Advanced Gas Fracturing System was examined as new technology which showed the ability to produce gas with very high pressure reaching 32,000 to 46,000 psi. For an Unconfined Compressive Strength between 16000 psi and 26000 psi observed in the subject reservoir, the high-pressure gas surpassing it by 2 to 3 times, is expected to create lateral mega to macro-fractures around the well for up to 98 ft diameter pool in 9 - 12 millisecond, with maximum gun size. The Advanced Perforation system in conjunction with optimized acid system were designed for the for the highest rock strength sections to achieve and maintain maximum connectivity between reservoir and wellbore, becoming a great alternative to hydraulic fracturing. Advanced stimulation techniques including the use of tailored emulsified acids, with Abrasive Jetting tool application to improve placement and productivity, were evaluated in ultra sour tight reservoirs.