What follows is an abbreviated project profile on Stella Maris’ custom-designed Geauxpher Chemical Injection System, which was custom-designed for Mariner Energy.

Client: Mariner Energy

Project: Geauxpher Chemical Injection System

The Task: Mariner Energy, an independent oil and gas exploration, development and production company with principal operations in West Texas and the Gulf of Mexico, called upon Stella Maris to design and build a Chemical Injection System capable of supplying 8 gallons of methanol per minute at 15,000 psi, as well as provide the capability to slipstream low dosage chemicals with the methanol.

The system, which would be dubbed the Geauxpher Chemical Injection System, required the design, fabrication and testing of a skid with pumps and plumbing necessary to support hydrate inhibitor injection, hydrate inhibitor dosing and corrosion inhibitor for two subsea wells.

Design/Fabrication: Four 0.6 to 4.0 gpm at 15,000 psi, 60 HP, VFD-controlled, electric-driven triplex piston pumps were proposed to inject hydrate inhibitor to the subsea wells. The suction to these pumps could be selected from either LDHI or methanol. This enabled the operator to pump methanol to one well for compliance testing while maintaining normal injection of LDHI to the other. Each well featured a dedicated pump with the third and fourth acting as backup to either well. Any pump would be capable of being redirected to any well for flexibility. Each pump was fitted with inlet and outlet pulsation dampening, discharge gauge, PSV, pressure transmitter, check and bleed valve. The discharge was routed to a selector manifold to direct the flow to the desired well. The final outlet for normal injection to each well was fitted with a flow meter with a local readout and 4-20mA output for remote monitoring. The pressure transmitter and flow meter signals were routed to a skid-mounted junction box to be terminated and connected to the control system. The hydrate inhibitor pump system is intended to be used for dosing by directing the outlet of two pumps to a single outlet and using the VFD to control flow rate. This method allowed for a dosing rate of up to 8 gpm to a single well.

In order to ensure positive supply to the triplex pumps, three sets of booster pumps were proposed and, upon client approval, ultimately implemented. Each set included two diaphragm pumps, each capable of 25gpm, and filter regulators for the air drive control, individual pump SDVs, discharge gauges, PSVs, pressure transmitters, checks and bleed valves.

Each set drew chemical from separate chemical tanks (LDHI, methanol and “spare”) and supplied independent suction headers to the bank of triplex injection pumps. The pumps’ were designed to supply the chemical injection system with positive suction pressured and was set to stall in instances when chemicals are not being consumed. When the main injection pumps begin consuming chemicals, the pumps automatically would begin pumping. The pairs of pumps in the system were designed to be plumbed with stainless steel tubing and to discharge through a set of redundant filters. Filtration upstream of the pumps would reduce pump maintenance.

Testing: After independently hydrotesting the tubing system our technicians built, Stella Maris temporarily installed one of the projects VFDs and mocked up a methanol supply and return system. With primary overpressure protection systems in place each pump set was run up to full pressure and rate. All flow meters were tested with methanol. Critical parameters such as motor and pump temperatures, pressures and flows were logged and documented on our FAT documentation.

To learn more about the intricacies of this or other design-and-build projects, or to discover how Stella Maris can design and build a custom system to fit your company’s unique needs, contact us at 337-504-5128.