Oil and Gas Field Development Studies

EnSys Yocum and its affiliate Yocum Consultants design and evaluate alternative field production facilities development schemes (wells through surface/gathering, separation, measurement and transmission facilities) and optimize designs for best life of field performance consistent with reservoir/fluid properties data and projections.

Some examples of our work include:

• For a major North Sea field, a technically feasible three-phase subsea production system with 46 wells connected to a 450' riser to the process platform was designed and simulated over the life of the field, then compared with a multiphase study based on installing a well platform with the wells connected to the separator/process platform by a 450' downcomer into a trunkline flowing into the 450' riser. A detailed analysis of costs, risks and future problems was made. The alternative system designs were simulated over a 10-year period with high accuracies obtained on the wells through the risers etc.
• For Alaska Prudhoe Bay, we ran simulations of the performance of 12" and 16" three-phase trunklines gathering flows from multi-well clusters and supplying the gas/oil separator flow station. An overall plan and detailed design layouts of the flow elements and facilities were prepared and formed the basis for project recommendations. The maximum flow capacities of the system trunklines and gas/oil separator trains were determined. Simulations were carried out based on reservoir predictions of flowing bottom hole pressures and fluid properties each year for 10 years.
• For SUCO Egypt, we simulated the gas lifting of the Ras Budran wells and determined the depth of injection points, location of gas lift valves and gas injection rates. We calculated compressor horsepower requirements to produce the optimum oil producing rates. We designed facilities modifications to balance the total system and simulated the application of downhole submergible pumping Ras Fanar wells.

Production Facilities Design/Performance

EnSys Yocum undertakes focused simulation studies of existing or new production systems to identify and remove bottlenecks, raise throughput and optimize separation efficiencies.

Some example of our work include:

• For Unocal (offshore Indonesia), we simulated offshore two-phase and onshore multistage, 2/3-phase separators to assess capacity constraints and the potential for raising production, including by enabling produced water to be discharged offshore rather than transmitted ashore. Our simulations of water-in-oil and oil-in-water on three-phase separations closely matched actuals. Our results confirmed the severe under-sizing of the offshore separator. Design options were presented to debottleneck this and enable production to be raised by 30,000 bpd.
• For Preussag, Venezuela, we modeled and designed a multiphase trunkline system with feeder lines along the path for an existing field with low wellhead pressures. We optimized flowlines versus pump and compressor stations. The final design achieved several million dollars in capital and projected operating cost savings versus client's initial concept.
• For Caltex, Indonesia, we analyzed horizontal and vertical separator design options for heavy oil, high water cut, high viscosity emulsion. Our studies prevented the development of severely undersized separators and led the client to adopt novel design concepts saving millions of dollars versus the correctly sized conventional separators we designed.

Multiphase Flow Measurement and Reconciliation

EnSys Yocum provides software and support services to enhance the performance of multiphase and wet gas meters, reconcile mass balances and flows versus multiphase and single-phase meters. We also supply "virtual metering" technology for complete flow measurement and reconciliation across a producing system. 

Some examples of our work include:

• For Texaco North Sea Erskine field, (HPHT with retrograde condensation), we implemented our PVT Meter software to correct flowrates from the six Erskine Framo multiphase meters. PVT Meter software was installed offline and integrated within the shore-based production workstation, correcting flows on a daily basis.
• For Roxar ARCO Alaska, we integrated our PVT Meter software into Roxar (MFI) multiphase meters for real time application in two multiphase meters with partial separation configuration. SPE paper 54605, "Multiphase-Flow Measurement System of High-GOR Applications," discusses this application, which achieved high accuracies