One of essential parts of hydraulic fracture job design optimization in deep sandstone formations is to conduct a minifrac test using fracture fluid to identify the closure pressure for calibration of the stress profile and to calibrate the leak-off coefficient of the fracturing fluid, but the test could not provide good understanding for reservoir properties of permeability, reservoir pressure, and intensity of natural fractures.
By conducting the actual DFIT (Diagnostic Fracture Injection Test) and minifrac in more than thirty wells in different formations from different fields, several leak-off behaviors are observed and several conclusions can be reached by integrating minifrac, DFIT, geologic settings information, and production data.
With the experience of conducting high rate and low rate DFIT before minifrac jobs, we can conclude that there are several benefits for the DFIT by replacing the minifrac, which conventionallyusesg a polymer fracturing fluid, with a non-wall-building fluid consisting mainly of water from the operations and job design perspective, and from the post frac production perspective. DFIT with water can introduce the best methodology to detect the induced complexity that may cause hydraulic fracture job cancellation in cases of detecting high complexity value early before rig movement. Implementing DFIT in a complete hydraulic fracturing design, execution and evaluation workflow can provide a deep understanding of the fracture geometry propagation and reservoir characterization. The main disadvantages of the DFIT is that it requires a long leak-off observation period but that can be minimized in the mD range of sandstone permeability.
This paper introduces DFIT in sandstone formations as a good method for integration between the geology, reservoir management, and fracture operations. The paper provides the operational and integral benefits of replacing minifrac and fracturing fluid with DFIT and water in deep sandstone formations, which provides more accurate data analysis because testing is done with same fluid. In addition, it can reduce fracture operations cost by 10%.