Multiwell experiment: Fracturing experiments

Conference · Thu Jan 01 04:00:00 EST 1987

OSTI ID:6310065

Warpinski, N R; Sattler, A R; Branagan, P T; Cipolla, C

Because of the complexity of the stimulation, no conventional analyses were useful, so we decided to concentrate on the minifrac to provide important fracture parameters. The minifrac was conducted in an identical manner to the pressure-up and pad stages of the stimulation. Figure 1 shows two initial pressure-history match calculations that were performed to model the minifrac. We found that the pressure behavior could not be matched with any normal behavior. Examining the field pressure data, we see that the interesting feature is the sudden flattening in the pressure at a level 1050 psi above the closure stress during pumping and the rapid drop to this same level at shut-in, after which the pressure decreases much more slowly. We first tried to match this behavior using enhanced height growth. While height growth can flatten the pressure during pumping, it also causes a very slow pressure decline at shut-in. We also tried additional leakoff height as height grew, but this could not flatten the pressure as much as needed. Finally, we tried an accelerated leakoff condition above 1050 psi. We did this by increasing the leakoff coefficient by a constant factor above some threshold value. To keep the results smooth and code convergent, we actually linearly phased in the increased leakoff between 1000 and 1100 psi. The final result of these calculations is shown in Figure 2; a factor of 50 increase in the leakoff coefficient was required to match the data for pressures above 1050 psi.

• Research Organization: Sandia National Labs., Albuquerque, NM (USA); CER Corp., Las Vegas, NV (USA)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 6310065
• Report Number(s): SAND-87-1543C; CONF-870728-1; ON: DE87012398
• Country of Publication: United States
• Language: English

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