Abstract
This paper covers a brief description of common solid particulate diverters used in stimulation treatments; discusses the development of a unique state-of-the art solid particular diverting system (SPD); and compares it with conventional diverters. Results of four case studies are also presented.
After 10 years of shale/unconventional well completions in the US, operators are still striving to determine the nearly perfect multi-stage fractured horizontal well completion that produces hydrocarbons from all fracture stages/perforation clusters. Why? The most commonly accepted explanation is that complete, uniform fracturing has not been achieved, especially as lateral lengths, number of frac stages, and perforation clusters increased, and stage spacing reduced. Like all liquids, stimulation fluids follow the path of least resistance. In heterogeneous reservoirs, this commonly results in some over-treated zones and some untreated perforation clusters within a stage. An economical solution was found in an old, but newly designed technology: diversion.
Since mid-2014, the new diversion technology for near-wellbore applications has been used in more than 1,050 frac stages (66 wells) and 17 acidizing operations, for 17 different operators in 14 different unconventional plays. The four case histories presented within this paper include a six-well refracturing program in the Haynesville that resulted in average 60-fold production increase; an initial fracture stimulation treatment in the Bone Spring shale, leading to 50% more production than a direct offset fractured well with the same design, but without diverter; a three-well remedial acidizing program in the Woodford shale, Oklahoma, that resulted in significant production increases; and a 12-well initial fracturing program in the Eagle Ford shale, resulting in production rates comparable to or exceeding offset wells.
Fracturing and acidizing treatments have used a number of diversion techniques over the years; common diverting agents include benzoic acid flakes, Gilsonite, and rock salt. All aim to temporarily block high-permeability paths that are taking most of the fluid, thereby shifting subsequent fluids into the next-most permeable path. Still these conventional diverter systems are not engineered with an optimal particle size distribution to yield more effective diversion. Instead, a new state-of-the-art family of diverter systems has been designed with specific particle size distributions that enhance diversion. This unique family of non-damaging and dissolvable solid particulate diverters is applicable for normal and high-temperature reservoirs and effective for near-wellbore and far-field diversion.
