Failed wells, wasted investment

To improve productivity and long-term recovery in the aging Safaniya formation, the world’s largest offshore oilfield, Saudi Aramco had recently completed 26 wells in a revitalization project. However, all but two of the wells were dramatically underperforming—that is, producing no oil or only a very small amount. Neither Aramco nor the company that had installed the wells understood why the wells had failed. Schlumberger learned that Aramco was on the verge of abandoning the wells and drilling new one using conventional cased-hole perforating methods unsuitable for the horizontal wells and highly permeable, poorly consolidated sandstone—and offered to provide an alternative solution.

The Schlumberger solution, presented just one week later, included a number of components. The robust LineSlot shrink-fitted, wire-wrapped screen with slot gaps sized to keep out the sand but let in the oil would maintain gap size through the wellbores’ twists and turns, thus ensuring uniform flow. The ResFlow inflow control device with nozzles would be placed at intervals along each 38-ft section of wire-wrapped screen to automatically balance flow and stimulate less productive zones while reducing the risk of early water breakthrough. The new wellbores would have many more, much shorter compartments: instead of six long zones of 500 ft each, there would be more than 30 short zones, each only 80 ft long. More zones would mean greater control of the pressure and oil flow throughout the wellbores and less risk of flow stoppage in one of the zones.

Other Schlumberger technologies were also involved: the PeriScope bed boundary mapper to ensure proper well placement, StethoScope formation pressure-while-drilling service to optimize ICD design, MUDSOLV formation damage removal treatment, and FIV formation isolation valve, combined with the QUANTUM packer to allow future ESP workovers without killing the well.

The biggest challenge Schlumberger faced was coordinating the manufacture and delivery of the many integrated components, including 85,000 ft of custom-made completion systems, in an extremely short time. The team members involved in planning the project were aware of the risks, however.

Saudi Aramco accepted the proposal, even though it meant that the company would have to abandon all the wells already drilled and the huge investment already made with the previous service company.

Successful collaboration, dramatic results

Within just a few months, Schlumberger delivered all 32 new wells and greatly increased production from the aging Safaniya field. Moreover, because Saudi Aramco did not need to drill other previously planned wells, the company saved millions of dollars.