Abstract

The decreasing frequency and size of new oilfield-reserve discoveries and an increased demand for energy is forcing industry professionals to find more creative methods of extracting every drop of oil possible. Pinpoint stimulation is one of the processes that enables service companies to target smaller plays with treatments customized to their specific characteristics.

Throughout the ongoing evolution of this process, improvements are constantly being made to enhance the treatments. One of the latest improvements is the introduction of a coiled tubing (CT)/jointed tubing (JT) hybrid unit that combines the advantages of CT’s continuous movement with the rigidity of JT. For extended-reach horizontal sections, the hybrid-string hydraulic workover (HWO) jack supplies the horsepower to push it to bottom while the depth-reaching capability of the JT greatly exceeds that of the CT, which can buckle and lock up before reaching total depth (TD).

The equipment consists of an HWO rig-assist unit, reel trailer with powerpack, HWO tower with tubing guide, CT (top), JT (bottom), and a bottomhole assembly (BHA). The BHA includes a new-style safety valve that protects the flapper from erosion during sand pumping and can be surface or remotely activated for positive well-pressure control.

The advantages of running this configuration include the capability to run larger-sized CT for higher flow rates and faster treatments of longer horizontals, as well as the capability to continuously forward or reverse circulate.

In addition, the hybrid allows the JT to be hydraulically disconnected at the BHA after treating, thus leaving it in the hole as a completion or velocity string. This new technology is proving to be a new game-changer in well intervention.

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