Abstract

A new technique has been developed in Indonesia to stimulate heavily damaged wells in medium to high permeability sandstone reservoirs. The technique, called pressure-pack stimulation, consists of a very short fracture designed to provide a high conductivity path from a wellbore, through a damaged area and into an undamaged, high permeability reservoir.

The technique is designed to restore a damaged wells productivity to that of a totally undamaged state. The total fracture conductivity and the fracture area in the undamaged portion of the reservoir contribute to a flow capacity equal to an undamaged flow capacity.

The technique is particularly applicable to formations which are sensitive to aqueous based fluids and do not respond to matrix type damage removal treatments. Many of the producing formations in Indonesia fall into these categories.

The paper presents the design theory of short radius, high conductivity fractures and single well production simulations equating undamaged productivity to fracture flow capacity and fracture area. Due to the small treatment size, typically less than 2000 gals, conventional fracturing simulators cannot be used. Empirical modifications had to be made to calculate fluid loss, fracture width and conductivity. Subsequent field tests have verified these modifications. Proppant is pumped at a constant concentration ranging from 6-10 pounds per gallon.

Several case histories are presented for wells in Indonesia which describe pretreatment well test data (damage determination), treatment design and execution, and post-treatment evaluation.

The cost of pressure-pack stimulation has been about 60 percent of the equivalent matrix type treatment while overall results have been several times better. The paper also presents several other advantages of pressure-pack stimulation over other matrix type stimulation and lists several applications for both exploration and development wells including high angle and horizontal wells.