The technology advancement in horizontal drilling and hydraulic fracturing makes it economically viable in exploration of unconventional oil and natural gas resources where conventional drilling is ineffective. In fact, more than 90% of the wells drilled today are hydraulically fractured. Despite the efforts, there exists demanding challenges to reducing the cost of non-productive time during well drilling and completion. Traditionally, many downhole disposable tools such as frac-balls, disks or plugs that are used for sleeve actuation and isolation of different production zones during fracturing, or control valve actuation for production, are disposed artificially through either a re-entry such as drilling out or flowing back that is limited by the available lightweight materials subject to early yielding or severe shape change.
The concept of in-situ disintegrable tools made of materials that are lightweight, high-strength and have a controllable corrosion rate simplifies operations and represents an obvious advantage. In this work, the integration of light weight and a high corrosion rate is realized in the dissimilar metal composites forming micro-galvanic cells. Simultaneously, an ultra-high strength is achieved through engineering the micro/nano-matrix and secondary nanoscale metallic and/or ceramic additions. The corrosion tests were conducted in 3% potassium chloride (KCl) at 200 °F. The results show the nano-engineered composite materials exhibit a disintegration rate that can be controlled between 10 and 400 mg/cm2/h with ultra-high strength up to 80 ksi. The interaction mechanism between the matrix and nanoscale secondary phases was studied using scanning and transmission electron microscopy. The improved mechanical properties were analyzed in the framework of micromechanical models and the perspective to further increase the material strength was discussed. Field application tests show the completion tools made with the composites reliably eliminated artificial intervention and opened a flow path within controlled time in the natural downhole fluid.