Abstract

A new chemical injection valve run on coil tubing allows inhibitor treatment of well tubing without interruption of well production. Chemical injection is production. Chemical injection is controlled at the surface by hydraulic pump pressure and flow rate to provide uniform pressure and flow rate to provide uniform distribution along the entire tubing length. The inhibitor is discharged into the production stream and will rapidly deposit onto the tubing wall. The valve is deployed with existing coil tubing service equipment and a minimum of additional tools.

The Coil Tubing Inhibitor Valve is a back pressure regulator. The valve design is pressure regulator. The valve design is based on a state-of-the-art side pocket mounted chemical injection valve for wells completed with a continuous inhibitor system. The valve mechanism consists of a nitrogen biased piston directly connected to the valve stem. The piston has integral metal-to-metal seal cups that are sized to the cylinder bore for exceptional sealability. A redundant elastomer seal complements the rugged all-metal seal design. Inhibitor fluids discharging from the valve strikes a high speed turbine which breaks-up the discharge stream into a radially directed spray completely encircling the turbine. This discharge pattern provides 100% tubing wall coverage pattern provides 100% tubing wall coverage as the valve is moved upwards through the well.

Typical batch inhibitor treatment methods require production shut-in periods. With tubing displacement from surface treatments, the lost production period often includes an extended recovery time for the well to return to pretreatment production rate. With the coil tubing production rate. With the coil tubing injection valve the cost of treatment is offset by incremental production compared to treatments that require that the well be shut-in. The precise metering of chemicals over the target interval reduces the overall chemical cost by reducing over treatment and wasted chemicals.

Background

Corrosion inhibition chemicals are injected into producing oil and gas wells by a variety of methods. When severe corrosion is anticipated the completion may be equipped to allow injection of chemicals down the annulus and into the tubing. Usually a valve which opens and closes in response to the injection pressure is mounted just above the packer on the tubing string to regulate the chemical injection into the tubing bore. But in the vast majority of wells no such provision exists and corrosion inhibition can only be achieved by injecting chemicals through the tubing bore.

There are several methods of injecting chemical inhibitors into conventional tubing each with unique advantages and disadvantages. The tubing displacement method is typically a two step process of pumping fluid into the tubing then forcing pumping fluid into the tubing then forcing the fluid down the depth of the tubing. With the well shut-in a prescribed quantity of an inhibitor chemical is first pumped into the well bore.

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