Enhancing Production in Russia's Oil and Gas Fields

Nearly 100 participants in an SPE Applied Technology Workshop (ATW) in Moscow discussed the application of horizontal wells (HWs) and multilateral wells (MWs) in Russia, where horizontal drilling is widely practiced. Case studies were presented from western Siberia, Sakhalin, Canada, the Middle East, and the North Sea to stimulate discussion of where it is best to use HWs and MWs and, alternatively, where other forms of production enhancement such as hydraulic fracturing might be more appropriate. The second part of the workshop focused on execution—drilling, completion, and life-of-field monitoring.

Status of Well Technology

Sibneft Chief Engineer Iskander Diyashev opened the discussion, describing how the company has enhanced production in its Noyabrsk western Siberia operation with 50% of the increase coming from HWs (even though these wells make up only 4% of the total well stock). TRACS-Consult Petroleum Engineering Consultant Robert Holtslag gave an overview of HWs in Russia where there are 2,500 of a worldwide total of 75,000. The Russian wells have productivity improvement (PI) factors in the range of 1.2–3. Holtslag pointed out that a major challenge is to increase the lower end of this range so that more HWs have robust economics. Schlumberger Middle East Chief Reservoir Engineer Fikri Kuchuk examined HW and MW performance, emphasizing the shortfall in performance as a result of inadequate cleanup, water sumps in the wellbore, and uneven pressure distribution in the near-wellbore formation that may reduce the PI factor to 30–50% of its potential value. He stressed the importance of drilling horizontal sections, which avoids sumps and highs where water and gas can accumulate. Sibneft Reservoir Engineer Elena Khairulina presented implementation of modeling HW performance using many examples from Noyabrsk.

Case Histories and Screening

Sibneft Reservoir Engineer Larisa Gaponova described the optimization of Sugmutsky field development by use of HWs. The peak oil production almost doubled with a much smaller number of wells. She compared a 500-m-long HW with a vertical well (VW) with a vertical hydraulic fracture. The initial PI factor was 4.4, stabilizing at a current value of 3, while the initial water cut was two times less than that from a typical VW and stabilized at 3.4 times less.

Sibneft Stimulation and Completion Engineer Andrey Brovchuk explained hydraulic fracturing of openhole HWs in western Siberia, showing that a post-frac improvement of 150% was achieved and that 3.5% of production was achieved from 14 HWs with hydraulic fractures.

Economides Consulting Partner Andronikus Demarchos described a transversely fractured HW in Algeria where four fractures were created with 70-m spacing along an HW. Each fracture used 100 to 200 tons of proppant. Results will become known when bridge plugs, needed in order to create multiple fractures, are drilled out.

Shell Drilling Specialist John Ramalho concluded the session with reservoir characterization from underbalanced drilling (UBD). He outlined three applications: reducing drilling problems, preventing formation damage, and characterizing the formation during drilling. According to Ramalho, initially UBD is performed to improve the drilling process, but it also offers improved ultimate recovery of from 5 to 12%. All three applications create value through cost reduction, increased production, and recovery.

Drilling

Schlumberger Drilling Specialist Nelson Mohammed began the discussion of extended-reach drilling in Rosneft’s Odoptumorye field, operated in Sakhalin. Horizontal departures of 6000 m are being achieved. A critical problem caused by cavern formation occurs in the tophole section at a measured depth of approximately 2000 m.

Marathon Oil Drilling Managers Vladimir Belkin and Benjamin Meyerov discussed drilling HWs in the Bazhenov shale in western Siberia. Two wells have been drilled: The first (Sredne Nazymskoye 401) has been completed and tested without hydraulic fracture with an oil rate of 30 tonnes/d, and the second (Galyanovskaya 41) was tested post-hydraulic fracturing at 85 tonnes/d.

Rosneft FDP Deputy Manager Yevgeny Borodin described three applications of HWs in the Mamontovo, Komsomolskaya, and Vankor fields in western Siberia and Odoptumore in Sakhalin. In all cases, the use of HWs reduced the well count as compared with the original field development plan that had relied on VWs. The recovery factor was improved.

Completions

MI-Swaco Drilling Fluid Specialist Peter Ryabtsev discussed drilling and completion fluids, covering improvements since the year 2000 in the areas of products optimization, bridging-material selection software, production-screen tester, and filter-cake breakers. High-density (to 1.42 specific gravity) fluids have been achieved without barite. Oleophilic filter cake in water-based mud avoids the need for chemical cleanup and reduces water cut.

Sakhalin Energy Investment Co.’s Mike Gunningham reviewed cased-hole vs. openhole completions in HWs. Baker Oil Tools Reservoir Engineer Lukacz Ostrowski presented inflatable tools for selective testing and stimulation of hydrocarbon intervals.

Halliburton Drilling Fluid Specialist Andrey Kharitonov presented drill-in fluids and cleanup, showing the importance of filtering and the use of acid precursor and/or enzyme. In this application, the acid was generated in situ, and good filter-cake cleanup was obtained on Sibneft’s Sporyshevskoye field. The audience split into three syndicates to review three completion topics: well testing, filter-cake cleanup, and important factors affecting the adoption of HW technology in Russia.

Applicable Technologies

Rosneft Reservoir Engineer Dmitri Antonenko showed how the company uses a matrix to introduce new technology. They plan to pilot: UBD on coiled tubing to reduce wellbore skin damage (now in the range of +5 to +30); geosteering to keep the wellbore inside the reservoir when drilling extended-reach wells in thin beds; intelligent completions to help counter gas breakthrough on the Vankor field; and hydraulic fracturing of HWs as tested by Yuganskneftegaz, who implemented a pilot that achieved a six-fold production improvement compared with the average of hydraulically fractured wells in the field.

WellTec President Jorgen Hallundbaek presented downhole well intervention by use of tractors. He showed that a large variety of well work such as logging, perforating, plug setting and pulling, shifting of sliding sleeves, milling, drilling, acidizing, and cleanup can be carried out with wireline- or coiled-tubing-conveyed tractors. Some benchmark parameters achieved so far: longest run of 6000 m, deepest run of 9300 m, highest temperature of 165°C, and highest deviation of 130°.

Halliburton Multilateral Technology Completions Engineer Mikhail Goncharev reviewed the principal motivation for using MWLs—to reduce drawdown by using more branches with consequent greater exposure of wellbore to reservoir. He showed some advanced applications from Middle East reservoirs.

Kuchuk gave the final presentation, titled “Technology’s Role in Production Optimization and Recovery Efficiency,” which involved extending the production plateau and producing more from mature reservoirs, exploitation of marginal reservoirs, gas exploration and development, and water management. Real-time reservoir management through surveillance and monitoring needs to measure the pressure and saturation distribution between the wells, with focus on locating the remaining bypassed oil. New technology is paramount in increasing production and recovery through better reservoir management, development, and real-time production monitoring.

The ATW closed with a panel discussion when the speakers from the last session were joined by Ramalho. Issues raised included the need for more open sharing of information between operating companies, service companies, Russian design institutes, and software developers, helping to capture expertise and counteract the shortage of experienced people. The next steps into offshore Arctic and eastern Siberia will be an enormous challenge, given current industry shortcomings.

The ATW Steering Committee, cochaired by Tim Samuel of Sperry-Sun and John Gallivan of TRACS-Consult, included Andy Barker of Baker Hughes, Iskander Diyashev and Andrey Brovchuk of Sibneft, Fikri Kuchuk and Nelson Mohammed of Schlumberger, Murray Vasilev of PetroAlliance, Michael Pogrebin-sky of GeoTrend, Nick Hore of MI-Swaco, and Tom Morris of Shell.

Information provided by J. Gallivan and R. Pepelyaev, TRACS-Consult.