Initial production from an openhole horizontal in the Rotliegend formation was uneconomic and a small acidizing treatment was unsuccessful. Resin coated 20/40 HSP was used at up to 9 ppg in a designed TSO to maximize conductivity, increasing production over 800%.
The hydraulic fracturing of uncased wells or wells completed with a pre-drilled liner carries a risk of early proppant screenout. On the other hand, this can be a very cost-effective completion and stimulation method. This paper describes the successful application of multiple hydraulic fracturing in a deep horizontal gas well, Boetersen Z9, which was completed with a pre-drilled liner.
The first step in the design of the treatment was to determine the optimum positions of two propped fractures with information from a production log and from multifrac inflow simulations. Weakening the rock by perforating would raise the probability that two hydraulic fractures would he created at these positions during fracturing. The actual positions of the fractures were later estimated from the minifrac analysis. The main pumping treatment was an extension of common practice. Pump rates were maximized so several fractures could grow simultaneously to the planned length and width. A large stage with medium proppant loading was pumped to confirm access to the fractures before stages with higher proppant loadings were pumped. Precise stage volumes were inferred from the minifrac and took into account the uncertainty in the actual positions of the fractures. Resin-coated proppant was used throughout the job, rather than being used as a tail-in only, because fractures could become packed off at any time during the job and proppant flowback is avoided for each of them.
The well capacity increased from 7000 m3/h at 100 bar FWHP to 20000 m3/h at 370 bar. Skin and good communication between the fractures and the open-hole wellbore may have contributed to the success of the treatment.
Author(s): Halliburton, H. Kamphuis, R Aretz, BEB Germany; G. Nitters, Shell; H. Loidl
Paper Number: SPE 50609