Lukoil encounters challenges in Caspian Sea

Lukoil was targeting a thin oil rim of approximately 20 m [65.6 ft] between an active gas cap and the water zone. The first phase of the development plan was to drill extended-reach horizontal wells equipped with inflow control devices (ICDs). After several years of drilling and production, most of the wells encountered catastrophic gas breakthrough, and production declined to critical levels 3 months after the breakthrough. Therefore, extended-reach wells with ICDs were not flexible enough for this challenging oil rim environment.

Schlumberger technologies enable maximum production and delay gas breakthrough

To delay the early gas breakthrough and maximize oil production, Lukoil and Schlumberger developed an advanced multilateral well design using multiple Schlumberger technologies. The resulting well design included one horizontal mainbore and one horizontal lateral. This addressed Lukoil's concerns regarding the feasibility of successfully placing extended-reach wells in the target zone while maintaining the necessary ROP and wellbore stability in preparation for a one-trip casing exit.

• The well was drilled using PowerDrive Xceed ruggedized rotary steerable system with EcoScope multifunction logging-while-drilling service  and TeleScope high-speed telemetry-while-drilling service to place the extended-reach well precisely between the active gas cap and the water.
• Bits from Smith Bits, a Schlumberger company, and DBOS OnTime real-time drilling optimization service provided significant ROP and real-time optimization of the drilling process.
• The laterals were drilled with MEGADRIL oil-base temperature-stable invert-emulsion drilling fluid system from M-I SWACO, a Schlumberger company, to ensure stability and propercutting removal.
• GASBLOK gas migration control cement system and LITEFIL cement additive for low-density slurries were used to achieve an excellent cement bond and successful casing exit job.
• The TrackMaster CH cased hole whipstock system performed as planned, providing a one-trip casing exit with a window of predicted geometry.

The RapidX TAML 5 high-strength, hydraulic-sealed multilateral junction was recommended because it provides the flexibility to drill sidetracks in any interval of the well. The junction also

• provides hydraulic isolation, avoiding production of undesirable fluids
• overcomes slot constraints on the platform, preventing disruption to existing operations
• achieves higher productivity index, leading to increased production
• reduces gas breakthrough, prolonging the life of the well

The intelligent completion string included WellWatcher Quartz premium high-temperature, high-resolution PT gauges and TRFC-HD flow control valves to help monitor and control each leg of the well separately and, in the event of catastrophic gas breakthrough, choke off one of the laterals to maintain production while controlling GOR. Along with the SFIV-II surface-controlled bidirectional isolation valve protecting the lower completion and the TRMAXX surface-controlled subsurface safety valve providing the isolation barrier, the multilateral installations and processes were all performed with zero NPT—even with the short time given for delivery and preparation.

Lukoil saves USD 6.8 million and prolongs life of well

Using this interdisciplinary approach of intelligent completion and multilateral technologies, Lukoil was able to resolve many of its technical challenges, including slot restraint, low recovery factor, high GOR, catastrophic gas breakthroughs, and noncontributing toe zones of the extended-reach multilateral wells. The well consistently produces approximately 3,200 bbl/d, and the oil/water ratio and GOR show better dynamics than other nearby wells.

This new well design saved Lukoil USD 6.8 million by eliminating the need to drill an additional well to keep developing the field. Because of the well's success in increasing oil production and delaying production decline, Schlumberger has secured at least seven more jobs in the North Caspian.

More details

Read more technical information in the technical papers, First Intelligent Multilateral TAML5 Wells on Filanovskogo Field and TAML-5 Intelligent ERD Offshore Well: A Case Story of Successful Application in the North Caspian.