Simultaneous Injection and Fracturing Interference Testing SIFIT – A Novel Technique

Abstract

Wireline formation testers (WFTs) are a major component of providing quantitative geomechanical information obtained through induced hydraulic fractures, commonly called (Micro-Frac). This type of information is used to infer critical data such as borehole stability studies, field stress mapping, stimulation planning, seal integrity tests, and other applications. Likewise, vertical interference testing (VIT) conducted with WFTs provides valuable information about flow barriers, zone connectivity, and quantitatively determine localized horizontal and vertical permeabilities. Both techniques are used over separate stations and different depths as it may involve different hardware in different trips in the wellbore. In this paper, a novel technique to combine both tests simultaneously using an optimized hardware configuration and interpretation will be demonstrated. Pressure tests data in low permeability reservoirs is commonly affected by "super-charging" fluid that leaks into the invaded zone from hydrostatic pressure and cannot quickly dissipate, thereby making it difficult to accurately obtain true formation pressure measurements. This, in turn, affects the VIT tests where the pressure response at the observation point is influenced by the supercharged pressure resulting in erroneous calculation of vertical permeability. By initiating a micro-fracture while monitoring its response, this provides a better estimate to reservoir pressure and improves VIT success in low permeability formation. The combination of a Micro-Frac and VIT test at the same depth provides unique information about the reservoir and may enhance the data quality on these stations. Not only the safety and cost are positively impacted in improving the operational efficiency. New methods and techniques can emerge from the utilization of this methodology and improve reservoir understanding and characterization. In fact, a feasibility test using this unique approach was conducted and validated in a carbonate reservoir. The results indicate that the created micro-fractures provide a means of dissipating the "super-charging" effect masking the true formation pressure and reduce the uncertainty in the calculated reservoir properties using the VIT data. This technique may be further developed to include, for future implementation, other sensors at different places and positions in the downhole modular tools in order to acquire more information that will bring novel insight on the tested reservoir zones.