Abstract

Multi-point hydraulic fracturing in unconventional hydrocarbon-bearing shale reservoirs has proven to greatly enhance production economics. Recent technology has allowed for as many as 40 individual fracture points. Tripping balls are a major component of these multi-point fracturing systems and are used to actuate fracturing sleeves to pinpoint fracture initiation and placement. While seated on ball seats, the tripping balls may experience pressures approaching 10,000psi. However, following a successful formation fracture, the tripping balls may hinder production. Potential problems relate to the tripping balls becoming stuck on the fracturing seats. Tripping balls remaining in the lateral can also lead to problems if wellbore re-entry is required. These production risks can lead to significantly increased costs and potential lost production. A new, high-strength corrodible material has been developed for tripping balls to alleviate potential problems in these unconventional reservoirs. This material has yielded an interventionless means of flow assurance. The mechanical properties and degradation rates of these newly engineered materials have been investigated to determine the downhole characteristics. The characterization results of these materials are discussed in an effort to develop a method for accurately predicting the timeframe in which these high-strength corrodible tripping balls fully degrade, and thus eliminate possible production risks. The testing included investigations of the degradation rates of these materials in brines, and at various temperatures. Materials were also pressure tested on multiple ball seat configurations used in the multi-zone fracturing systems1 .

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