Hydraulic fracturing is frequently used to create enhanced wellbore connectivity to enable tight reservoirs to produce hydrocarbon. Many factors can be considered as risks to the success of fracturing operations. One of the risks arises in reservoirs that are close to a water-bearing zone. The risk of fracture growth into the water zone limits the stimulation options and eliminates the chances of using hydraulic fracturing treatment to improve well productivity, thereby restricting the well's future production and often resulting in lost recoverable reserves. In the Western Desert of Egypt, two wells were to be fracture stimulated with a risk of propagating into a nearby water zone. The productive pay of low-permeability reservoirs is separated from underlying water zones by a weak or no stress barrier. The proximity of the water zone to the hydrocarbon-producing zone varied from 20 to 40 ft, and containing the fracture height in such well conditions to prevent the fracture propagating into the underlying water zone becomes a serious challenge. This can jeopardize the post treatment well productivity. It therefore becomes necessary to prevent fracture height propagation from growing into the adjacent water zone.
This case study presents a novel hydraulic fracturing technique, applied for the first time in Egypt's Western Desert that controls fracture height growth in the absence of in-situ stress contrasts. This technique places an artificial proppant barrier below the pay zone, close to the water-oil contact, creating high resistance to fluid movement and restricting pressure transmission, thus arresting unbridled vertical height growth of fractures. These barriers are created prior to themain fracture treatment by pumping heavy proppant slurry at fracturing rates carried in a fracturing fluid loaded with high breaker concentrations. The high breaker concentration breaks the gel fast, thus allowing the proppant to settle quickly to the bottom of the created fracture. The results from the application of this newly applied dual fracturing treatment technique have been overwhelming, with a 12-fold increase in production with no increase in water production. The application of this technique resulted in an increase in the net pressure at the end of main fracturing treatment indicating fracture containment within the zones of interest. The minifracture analysis, stress profile calculation, fracture geometry characterization, and no water breakthrough after the treatment support the fracturing design.