Liam Jones details how electric actuators powered by solar panels improve shale gas well pressure stability in USA
The Haynesville/Bossier rock formation dates back to the Jurassic Period and covers large parts of South West Arkansas, North West Louisiana and East Texas in the USA. The formation contains large quantities of natural shale gas sourced from low permeability mudstones.
Why Does The Pressure Stability Need Improving?
Rotork’s customer required an actuation solution to carry out modulating duties on wellhead rotary non-rising choke valves in the East Texas section of the formation. The remote location of the wells meant a system that could operate effectively without a mains electricity supply was specified.
How Was The Pressure Stabilised?
Rotork IQTF electric actuators were installed and powered by a DC supply using a solar system and battery pack. This was considered a more reliable option than hydraulic or pneumatic actuation as it avoids potential leakage common in hydraulic actuators. Electric actuators also use less power than hydraulic alternatives while the long hours of sunlight can be used as a reliable solar power source.
The lightweight, compact IQTF actuator offers fast and accurate valve control and can perform up to 1,800 starts per hour. This was an important factor as a tight well threshold was needed 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.
Rotork Site Services carried out final commissioning while support was also provided during initial testing and calibration.
The Results
The actuators are controlling 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 to operate choke valves to step pressure down from 10,000 psi to 1,200 psi. The shale gas is metered between the wellhead and midstream trunkline where it is transported to domestic supply customers and industries including LNG plants and power stations. More than 30 are also being held in the customer’s inventory.
Since installation the flow rate at the wellheads has been within a tighter tolerance. This is important to maintain the stability of the well and flow as well as the pressure into the main trunklines.
The IQTF actuators combined with solar systems have proven so reliable that the customer is now using the solution at two of its other production sites, Shreveport in Louisiana and Eagle Ford in Texas.
The actuators are helping the customer produce 190,000 barrels of oil equivalent per day in Texas and Louisiana through activities at both the Haynesville and Eagle Ford basins, as well as the Permian-Delaware basin.
Liam Jones is with Rotork
