Successful Case Histories of the Conformance-While-Fracturing Technique in Egyptian Western-Desert Reservoirs

Abstract

Abstract Hydraulic fracturing has proven to be extremely successful in the western desert of Egypt. Approximately 85% of production in this area results from this stimulation technique, specifically in the reservoirs of interest documented in this paper. However, a deterrent to fracturing in many cases has been the proximity of the producing zones to underlying (or overlying) water zones, either located near the water-oil contact or hydrocarbon zones adjacent to water-bearing zones. In the absence of geological barriers, the fracture height can grow uncontrolled during a fracturing treatment into the water-bearing interval and cause unwanted water production. Excessive water production threatens the economics of a well by: shortening its production life, increasing disposal and lifting costs, boosting the fines migration, and increasing the rate of tubular corrosion and scale buildup. Many times, in marginal fields, these can be sufficient reasons to consider not fracturing. This paper presents case histories where wells were hydraulically fractured using conventional techniques resulting in higher than 60% water cut (even as much as 100% in one case); while with the use of the conformance-while-fracturing (CWF) method, the water cut obtained was as low as 4%, even when the adjacent water zones were within 20 ft of the perforations. This technique provides a tremendous boost to the economics and an effective solution (increasing recoverable reserves from these wells by allowing the hydrocarbons to be produced almost water-free) to a field otherwise plagued with water production. The CWF technique incorporates a relative-permeability modifier (RPM) in the fracturing-fluids design. The RPM provides a reduction in effective permeability to water without significant changes to the relative permeability to oil. This paper discusses the geological and reservoir parameters of the wells and zones of interest, the properties of the RPM, the CWF job-design considerations (and the associated challenges to the job design), its field applications, and post-fracturing results in comparison to offset wells fractured conventionally in the same reservoir and at the same level. It is envisaged that CWF techniques will prove to be beneficial to other operators faced with similar production challenges.