May 2018, Vo. 245, No. 5
TechNotes
DRA, Optimizing Solutions Reduce Permian Operating Costs
With crude production rising quickly in the Permian Basin, a midstream pipeline company required an upgrade in available motor brake horsepower to enable the higher forecasted flow rates. However, constructing additional facilities, including motors and pumps, would mean significant capital investment and require long lead times. Before making this major decision, the company invited Optum Energy Solutions to offer a DRA-based solution.
Optum analyzed the client’s crude properties, pump performance curves and pipeline operational data. The system was a 16-inch pipeline, 49 miles in length and transporting 39 API gravity. The pump station operated two pumps in series, one with a variable-frequency drive (VFD).
The preliminary evaluation indicated when using Flow Optimizer, the pumps would still run in the preferred high-efficiency operating zone, even at the higher flow rates forecast. To confirm the feasibility of the DRA injection solution, Optum proposed a field trial to generate a performance curve that would then be used in the hydraulic simulation optimization algorithms for any transportation scenario.
Optum delivered a mobile, wholly enclosed tank and injection system to the site, fully instrumented for local or remote operation. The first injection of Flow Optimizer decreased the pump station discharge pressure from 710-210 psig at a pipeline flow rate of 5,400 barrels per hour (bph). Two additional DRA dosages were also injected to generate a drag reduction curve at the flow rate of interest.
The test results were extremely positive in this Permian Basin pipeline. Because multiple benefits were observed, the client adopted the DRA solution readily. Flow Optimizer’s dramatic reduction of the frictional pressure losses allowed for eliminating one pump and operating the remaining pump on the VFD at the higher flow rate required.
Capital expenditures on the additional pumps and motors as initially envisioned were also avoided. This represented a significant cost savings, and the reduced strain on the equipment is expected to prolong equipment life and contribute to improving the company’s mean time between failure (MTBF).
Compared with non-DRA pipeline operations, this process decreased the pump brake horsepower (hp) required from 5,233 hp to 1,656 hp, equivalent to nearly 65% reduction in electricity usage. In addition, the pipeline routinely operates at 7,800 bph. A flow rate increase of 44%. Factoring in the incremental cost of DRA, the operator realized a net cost saving of 24% during peak hours and 8% during off peak.
The client requested that Optum complete a site survey for installation of a permanent injection module. Injection began less than one week.
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