Rotork electric actuators powered by solar panels on US gas production wells

29/05/2019

Rotork intelligent full-turn electric actuators have been supplied for upstream shale gas production wells in the USA.

Engineered for choke and control valve applications, Rotork’s IQTF actuators provide reliable flow control for oil and gas or process operations, capable of achieving accuracy to 0.3% and resolution to 0.1%. A highly accurate absolute position sensor can measure up to 22 output turns independent of electrical power.

Rotork’s customer has ordered IQTF actuators to carry out modulating duties on wellhead rotary non-rising choke valves at the East Texas section of the Haynesville / Bossier shale gas formation, a Jurassic Period rock formation covering large parts of South West Arkansas, North West Louisiana and East Texas.

Approximately 60 actuators have already been installed to control the flow and pressure of gas and condensate, a mixture of liquid hydrocarbons formed when pressure and temperature decrease as a result of well drilling, at the site near the city of Lufkin. Two IQTF actuators have been installed on each well. More than 30 have also been ordered to hold in the customer’s inventory.

All wells at the Haynesville formation are fully automated to maintain flow and well pressure. To maximise the lifespan of the wells, the customer uses two choke valves on each one to step pressure down from 10,000 psi to 1,200 psi. Shale gas is metered between the wellhead and midstream trunkline where it is transported to domestic supply customers as well as industries including LNG plants and power stations.

The remote location of the wells means a DC power supply using a solar system and battery pack is being used to power the IQTF actuators. This solution was specified as a more reliable option than hydraulic or pneumatic actuation as it avoids potential leakage common in hydraulic actuators. Texas also has plenty of sun to use as a source while electric actuators use less power than a hydraulic system.

In a separate project, more than 60 IQTF actuators have been ordered for a new well site at the Eagle Ford basin in South Texas, where they will again be installed two per well. The customer’s operations in both the Eagle Ford and Haynesville basins, as well as its oil and gas assets in the Permian-Delaware basin, contribute to the company producing 190,000 barrels of oil equivalent per day in Texas and Louisiana.

Rotork’s lightweight, compact IQTF actuator provides fast and accurate valve control and can perform up to 1,800 starts per hour, an important factor given the need for a tight well flow threshold to avoid over pressure in the main trunkline. If too much gas is extracted in a short period of time the reservoir can implode or cause ground fractures which water or gas can infiltrate and cause a loss in production. The involvement of Rotork Site Services (RSS), which offered final commission and warranty, and Rotork’s support during initial testing and calibrating was also key in the customer’s decision to choose the company’s products.

IQTF actuators are available with rotary, linear or rising stem valve drive outputs to ISO / MSS standards.

A sealed for life internal lubrication system ensures reliability for the actuators installed on wells at unmanned, remote sites. This system uses oil which can perform in temperatures ranging from -50 to +70 °C (-58 to +158 °F), ideal for the environment in East Texas where temperatures very rarely drop below the lowest point.