Abstract

Most of the reservoirs in Ecuador are in mature fields with subhydrostatic pressure. To produce from these reservoirs, an artificial lift system must be included as part of the completion, and stimulation treatments are frequently required to produce economically.

Hydraulic fracturing is commonly applied today to remove formation damage, since the penetration of the matrix treatments sometimes is not enough to fully bypass the damage zone because of the depletion. However, in the U formation, after performing fracturing treatments, the maximum drawdown is limited to ensure proppant pack stability. Proppant flowback has been an issue in the first wells hydraulically fractured. Apart from the production limitations, the consequences of proppant flowback may include: decreasing of fracture conductivity, damage to surface and downhole equipment, additional operational cost, and loss of workover efficiency, one of the main factors affecting the Ecuador oil industry scenario.

All these consequences have created the need for a new approach to be able to produce these well economically without the mentioned issues. An innovative fiber-based technology for proppant flowback control (FBPFC) was proposed. At surface, low concentrations of short fibers are easily dispersed into the fracturing slurry. Meanwhile, at downhole conditions, the fibers are activated by temperature, becoming sticky and bonding with each other to create a continuous web that consolidates the proppant pack. The fiber web has negligible effect on conductivity, creating a stable proppant pack that is resistant to cyclic stress loading. This translates into higher drawdown and productivity.

The novel FBPFC technique has been successfully implemented in Ecuador, after determining the associated risk of proppant flowback, based on the geomechanical reservoir properties. More than 30 stages have been pumped with this technique without proppant flowback despite optimizing the drawdown after the treatments. This resulted in a four- to five-fold increase in production compared with a two- to three-fold increase in wells where the bottomhole flowing pressure was limited by the risk of proppant flow back. The use of FBPFC enabled the full potential of the reservoir to be realized.

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