Members SPE-AIME
Abstract An analysis is made to illustrate the effectiveness of a new second generation high strength low density proppant as compared to that of sintered bauxite and Ottawa sand in a variety of applications. This is accomplished through the use of a reservoir simulator and a fracture design program. Gas producing formations are simulated which exhibit permeabilities between 0.001 md and 0.1 md and closure stresses up to 9500 psi. In these simulations the second generation proppant and sintered bauxite yield essentially proppant and sintered bauxite yield essentially identical production histories. However, the second generation proppant shows far superior performance to Ottawa sand in all applications. Also shown are cases revealing that tail-ins with the second generation proppant can yield a higher return on investment than proppant can yield a higher return on investment than pumping all high strength proppant. pumping all high strength proppant. The simulations reveal the importance of non-Darcy flow and conductivity damage considerations in proppant selection. It is shown that these two factors have much less of an effect on the performance of the second generation proppant than on that of sand. With all of this considered the second generation proppant should prove to have a substantial economic advantage over both sintered bauxite and sand in a variety of applications.
Introduction As the search for gas continues to result in the completion and stimulation of deep tight reservoirs the demand increases for proppants which can withstand higher closure stresses than conventional fracturing sand. Sintered bauxite is the most commonly used proppant in formations where closure stresses are very proppant in formations where closure stresses are very high. It has been shown in the literature that substitution of sintered bauxite for sand can be economical in formations exerting high closure stresses. In many cases the strength of sintered bauxite is much more than is necessary to produce adequate conductitive. In other cases the high density of this proppant combined with its cost per pound make its use prohibitive. Until recently the alternatives to using prohibitive. Until recently the alternatives to using or sintered bauxite have been limited. This has led to a significant research effort directed toward the development of low density high strength proppants. In recent months, a "second generation" of high strength proppants has begun to surf-ace as a result of this research effort. It shall be demonstrated that one of these second generation proppants provides equivalent or superior effectiveness in many applications where sand as well as sintered bauxite are currently being used.
This second generation proppant has a specific gravity of 2.75 and a bulk density of 100 lb/ft3. Its permeability is near that of sintered bauxite at permeability is near that of sintered bauxite at closure stresses up to 12,000 psi. The cost of this proppant is considerably less than sintered bauxite proppant is considerably less than sintered bauxite thus providing an excellent alter-native to propping fractures in formations that exert high closure stresses.
In order to illustrate the advantages of using this new proppant, a comparison was made of overall production predicted by a reservoir simulator of wells production predicted by a reservoir simulator of wells stimulated with 20/40 second generation proppant, 20/40 sintered bauxite, and 20/40 Ottawa sand. Physical properties of these three proppants are shown in Physical properties of these three proppants are shown in Table 1. Permeability data for these three proppant was obtained in the laboratory using a procedure and apparatus described in the following section. These data were used in the reservoir simulator to provide a numerical comparison of the effectiveness of the three proppants in a variety of applications. Such an proppants in a variety of applications. Such an analysis allows the evaluation of well response to stimulation treatments resulting in fractures packed with:sintered bauxite
second generation proppant as a substitute for sintered bauxite
high concentrations of Ottawa sand
moderate concentrations of second generation proppant to replace nigh concentrations of Ottawa sand
Ottawa sand with high strength proppant tail-in
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