D51: Water Injection and Disposal Wells

Planning to convert or drill wells for water injection or effluent disposal? #AER Directive 51 (D51), Section 8.1, outlines initial #welltest requirements for either: 1) Step-Rate Injectivity test, 2) an In-Situ Stress test, or 3) a Mini Frac’ test (DFIT). In my experience the Diagnostic Fracture Injection Test (#DFIT) out-performs the step-rate test for initiating breakover. Perhaps, with each step-rate, the formation actually starts taking water, dissipating frac’ energy? Whereas the rapid increase in pressure, delivered by a mini-frac’ pumper, maintains maximum injection energy and power? Even if breakover isn’t achieved, the DFIT tends to preclude a higher Maximum Wellhead Injection Pressure (MWHIP). DFIT analysis (G-Function #PTA) can add even more value for reservoir engineering: closure pressure, fracture gradient, an extrapolated reservoir pressure (p*), and order-of-magnitude matrix flow capacity (kh).