Economic production from marginal reserves in mature fields has always been a major development challenge. Drilling horizontal wells and deploying coiled tubing (CT) multistage hydraulic fracturing stimulation treatments is now a proven solution for mature field development because it exposes more stimulated production zones. Khalda and Umbarka fields are two mature fields located in the Egyptian Western Desert. They are characterized by their low, depleted reservoir pressure and laminated shaley sands (Upper Bahariya formation). Their hydrocarbon reserve contents are significant. However, because of their relatively low permeability and thin layers, it is very difficult to produce economically from this formation without using hydraulic fracturing. Single-stage hydraulic fracturing treatments in vertically drilled wells resulted in a production of 25 to 40 B/D per well, which is uneconomic for field developments. Drilling horizontal wells into the best sand layer of the Upper Bahariya sand and performing seven isolated stages of hydraulic fracturing treatments by deploying CT technologies resulted in impressive production responses (1,800 B/D initial production) from this reservoir, which makes this development economical. Deploying CT to the operations exponentially improved its efficiency; seven isolated fracturing stages were performed along the lateral and more than one million lbm of proppant was pumped during three days through one single CT trip in the well. This paper provides a comprehensive description of the lessons learned from two case histories where CT fracturing techniques for multistage stimulation were applied to achieve maximum production in the field and improve the efficiency of multistage fracturing operations.
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