The working group WG398 of technical subcommittee ISO/TC67/SC7 has completed development of a new standard for geotechnical soil investigation (ISO 19901-8). The task has being carried out in the frame of complex offshore structure requirements development for petroleum and natural gas industries (series ISO 19901. Petroleum and natural gas industries — Specific requirements for offshore structures — Part 8: Marine soil investigations). The new standard is planned to be commissioned in 2014. It should be of interest to compare international and Russian practices in the area of offshore soil investigations, particularly at Arctic shelf with severe climate.
Traditionally in Russia requirements for engineering survey (scope and kinds of work) are defined by various normatives which have the state status (state and industrial standards, regulations, recommendations, guides etc.). On the other hand this kind of unification is more likely exclusion around the world (in particular national standards of USA, Norway and others); with more typical specifications and rules of some companies, institutes, societies, regional and inter-regional organisations. However shelf development is very global process, deleting boundaries and contributing integration of knowledge, experience and efforts. Therefore motion toward unification seems to be logical and expedient (under umbrella of International and European organizations for Standardization, ISO and CEN).
Kasumov, Timur (Lukoil) | Valisevich, Alexey (Lukoil) | Zvyagin, Vasily (Lukoil) | Kozhakhmetov, Mirat (Schlumberger) | Griffon, Romain (Schlumberger) | Mironov, Alexander (Schlumberger) | Long, Wiley (Schlumberger)
The pdf file of this paper is in Russian.
To effectively drain the reservoir formations in a Caspian Sea field from a single offshore ice-proof stationary platform (MLSP), the operator wanted to geosteer extended reach 8½-in (215.9 mm) lateral wellbores at maximum ROP and TD in one run. Development of Korchagina field would require several ERD horizontal wells with step-outs up to 8,000 m. The shallow true vertical depth (TVD) of the reservoir combined with low formation strength of the reactive shale requires high mud weight for stability creating a narrow equivalent circulating density (ECD) window. The hydrocarbons are trapped in an anticlinal feature with 70 m of natural gas cap rimmed by 20 m of viscous oil. To avoid early gas production that would lead to catastrophic water break-through, it is critical to keep the horizontal borehole in a narrow vertical corridor of 4-5 meters TVD to ensure maximum oil recovery. To accomplish the objectives would require the latest methods/technologies and would have to adhere to stringent environmental regulations.
Using an FEA-based design platform, a BHA solution was developed that contained a 716 type PDC bit fitted with premium 16mm cutters followed by a rotary steerable system (RSS) with an 8 3/8-in (212.7 mm) integral blade stabilizer and 6 3/4-in (171.4 mm) flex collar to enhance directional control. A new oil-based mud would be used to reduce friction factor/wiper trips and stabilize the reactive shale stringers that caused problems when rotating/sliding in offset wells drilled with water-based mud.
To fully exploit the integrated BHA's technological advantage would require establishing a defined set of best practices. In extended reach drilling it is important to monitor torque and drag trends to continuously analyze hole conditions to optimize connections and reduce trip time. Engineers determined that using relatively high pipe rotation (120-180 RPM) would maximize ROP and also enhance removal of drilled cuttings from the low side of the lateral hole section. The drilling team also recognized that reducing connection time is just as important as maximizing ROP because it can account for up to 40% of total drilling hours. To ensure efficient tool make-up, the number of pipe reciprocations was based on modeled torque/drag values enabling engineers to evaluate each stand to effectively manage circulating time prior to setting the slips.
This paper builds on the experience of managing and supervising marine seismic, sites and geotechnical surveys in Arctic regions over several years. Projects are reviewed for the purpose of highlighting technical issues peculiar to operating in extreme latitudes. Data examples are taken from operations offshore Greenland and in the Russian Arctic carried out since 2008.
Technical aspects discussed include: issues with project planning/ ice monitoring; geodesy; the limitations of satellite navigation systems in high latitudes; variation in sound propagation velocity; seismic streamer compass performance and magnetic dip/ field strength issues. The relative impact of these issues in different high latitude operating environments is compared and contrasted via experiences from Greenland and from the Russian Arctic, using data acquired during 2010 to 2012.
It is concluded that although Arctic operations may appear superficially similar independent of location, several technical aspects of the work, such as seismic streamer positioning, have a significant longitude component as well as a latitude component which must be taken into consideration when planning and executing operations. Mitigation proposals for future operations are suggested where feasible.
This paper describes some of the major issues around drilling world class ERD well in the Baltic Sea by a team of industry professionals from Lukoil, Schlumberger and Eurasia Drilling Company (BKE). The ultimate goal of the well construction organization was to deliver quality well under budget and within schedule with zero environmental impact.
A challenging well was successfully drilled to explore Cambrian production zone in D-41 structure. Key contributing factors to this success were:
- solid preliminary analysis,
- understanding of well bore stability by real time geomechanical modeling,
- comprehensive directional analysis,
- revised casing design,
- application of latest drilling technologies,
- creation of multi-discipline team with common goals.
The pdf file of this paper is in Russian. To purchase the paper in English, order SPE-166855-MS.
Advanced drilling technologies were used on two offshore multiwell platforms in the Lunskoye and Piltun-Astokhskoye fields, in the Sea of Okhotsk to deliver wells that required complex drilling to manage well-to-well collision risk, and to perform underreaming operations, extended-reach drilling (ERD), sidetracking, geosteering, and acquisition of thorough logging-while-drilling (LWD) data.
The project benefited from the successful implementation of a new concept that combined various groups of technical experts within the operating and service companies to address project challenges through proper well planning, 24/7 monitoring, and intervention, when needed, during the execution phase, as well as post-well analysis fed into the planning of subsequent wells.
The effectiveness of the collaborative drilling technical team was proven by the overall results since implementing the new concept. Four wells were drilled "shoe to shoe?? 25 days ahead of approved for expenditure (AFE) time for the drilling phase. More than 70 proactive interventions to prevent nonproductive time (NPT) were made and delivered to the drilling teams during trial runs; of these, 60% were considered significant and resulted in the implementation of a drilling and engineering operations planning service on subsequent wells. It was the first time in the Lunskoye field that a well had been delivered 8.9 days ahead of AFE for 53.6 days for the drilling phase. The success established good synergy among the client geoscientists and drilling personnel in town, platform teams, including the drilling supervisor (DSV) and offshore drilling engineer (ODE), and service companies providing mud logging services, drilling fluids, directional drilling and LWD services, and bits and underreamers.
Thanks to the successful results obtained from the collaborative drilling technical team concept, it has been accepted for use in this major offshore project as it brings continuous improvement to drilling operations through a cyclic process of planning-execution-evaluation.
Drilling and producing in high latitude environments is unforgiving. Temperatures often drop below -20°C and can reach as low as -50°C. Isolated locations or vast distances, extreme weather conditions and periods of deep darkness can restrict transportation of personnel and equipment. As a result, job complexity often leads to outright failure or an exponential increase in time to accomplish what would be a routine task in a normal environment. Often the best route to success and efficiency in these conditions is proven technologies and strategies. For over 80 years, e-line conveyance and tools have been refined and improved to become a very reliable means of data gathering and workovers, such as plug setting, debris removal, hardware milling, pipe recovery and so forth.
Modern electric line (e-line) capabilities can now accomplish what conventionally would have been rig- or coiled tubing-based workovers. In the North Sea, Canada, Alaska and Russia operators use e-line to perform ‘heavy' workovers; explosion-free cutting of tubulars, scale and debris removal, milling through hardware such as nipples, failed isolation valves and flapper valves, and replacement of hardware, such as gas lift valves and Electric Submersible Pumps (ESP's) in extended reach horizontals.
This paper discusses the benefits e-line tools can bring to accomplish ‘heavy' workovers in a reliable manner in high latitude environments. Several case studies are presented to demonstrate these applications in practice.
Unique challenges of high latitude operations
The Arctic region, defined as the area north of the Arctic Circle (66° 33'39" North), is apportioned among eight countries (Canada, Denmark (Greenland), Finland, Iceland, Norway, Russia, Sweden and the US (Alaska). Common to this region are key considerations such as personnel safety and operational stability of equipment in extreme temperatures.
The US Energy Information Administration lists a number of reasons detailing why development of this region may not be economically viable, including frigid temperatures necessitating custom equipment, logistical challenges and heavy investments in infrastructure and the high cost of labor to name a few.
However, according to an assessment conducted by the U.S. Geological Survey (USGS), the Arctic may hold as much as 13 percent of the undiscovered, global oil resources, 30 percent of the natural gas resources and 20 percent of the LNG resources, which makes the region increasingly attractive as the world runs out of ‘easy oil'. This translates into 90 billion barrels of oil, 1,670 trillion cubic feet of natural gas and 44 billion barrels of LNG. This means, the Arctic region may hold as much as 22 percent of the undiscovered, technically recoverable, global resources.
Therefore the Arctic is likely to see continued interest for exploration and production. The driver then becomes how to accomplish this successfully and economically. Reducing complexity and uncertainty seems an obvious answer, but in which parts of the workflow?
The pdf file of this paper is in Russian. To purchase the paper in English, order SPE-166929-MS.
The pdf file of this paper is in Russian. To purchase the paper in English, order SPE-166815-MS.
The geological studies carried out on the territory of the Taimyr autonomous district of the Krasnoyarsk Krai during the period of 1930-1950 by the Glavsevmorputi subdivisions, the USSR Mingeo organizations and the institutes of the USSR Academy of Sciences (AS) show a considerable thickness of sedimentary deposits perspective for oil and gas, the availability of the Paleozoic salt-bearing sections, the prolongation of the continental tectonic structures into the water area of the marginal seas followed by the increase of the sedimentary deposits The TAD borders on three oil and gas bearing provinces of Siberia such as the West-Siberian, the Khatango- Vilyuisk and the Leno-Tungussk the limits of which allocate the Enisei-Khatangsk OGR and partially the Pur - Tazovsk OGR. (20). The total area of the oil and gas potential lands is over 550 th square km (13).
The history of the development of the Arctic segment of the Earth form the view of the plate tectonics
In the process of the disintegration of the Pungea supercontinent the deposition of the Arctic segment of the Earth began. The course of crushing and dragging of separate sections of the Lavrasia continent and the simultaneous joining it up with small microcontinents resulted in the formation of the Arctic ocean basin with its numerous depressions and uplifts - ranges (15,18). In the Devonian the riftogenesis caused the formation of the oceanic basin of the recent Arctic Ocean (21) . The Arctic basin continued to exist as gigantic gulf of the Pacific Ocean without any changes from the Devonian to the Late Jurassic (4).
The early period of the formation of the Early Mesozoic rift systems of the West-Siberian platform, North-West Europe, the North Sea, North America the Paleozoic median-ocean ridges of the Arctic Ocean and the Atlantic Ocean witnessed the downwarping of large territories and the formation of the Permian sedimentary basins of the sedimentation (19,21)
The splitting of the lithosphere followed by the formation of the abovementioned rift systems ,the formation of separate microcontinents separated from the continental platforms by the foredeeps was observed in the Triassic (19).
From the Late Jurassic to the Late Cretaceous there was observed the formation of the ocean crust in the Makarov and Kanadian cavities.
The extension of the territory of the East-Siberian depression in the Upper Jurassic and the Early Cretaceous resulted in the formation of the East-Siberian lithospheric plate, and the spreading of the continental Taimyr block-microcontinent was followed by the formation of the Enisei-Khatangsk trough. The formation of the typical Hertzianocean results from the downwarping compensated by a powerful sedimentation (10).
Poedjono, Benny (Schlumberger) | Beck, Nathan (Schlumberger) | Buchanan, Andrew (Eni Petroleum Co.) | Borri, Luca (Eni Petroleum Co.) | Maus, Stefan (Magnetic Variation Services) | Finn, Carol A. (US Geological Survey) | Worthington, E. William (US Geological Survey) | White, Tim (US Geological Survey)
The pdf file of this paper is in Russian. To purchase the paper in English, order SPE-166850-MS.
Geomagnetic referencing uses the Earth's magnetic field to determine accurate wellbore positioning essential for success in today's complex drilling programs, either as an alternative or a complement to north-seeking gyroscopic referencing. However, fluctuations in the geomagnetic field, especially at high latitudes, make the application of geomagnetic referencing in those areas more challenging. Precise crustal mapping and the monitoring of real-time variations by nearby magnetic observatories is crucial to achieving the required geomagnetic referencing accuracy. The Deadhorse Magnetic Observatory (DED), located at Prudhoe Bay, Alaska, has already played a vital role in the success of several commercial ventures in the area, providing essential, accurate, real-time data to the oilfield drilling industry. Geomagnetic referencing is enhanced with real-time data from DED and other observatories, and has been successfully used for accurate wellbore positioning. The availability of real-time geomagnetic measurements leads to significant cost and time savings in wellbore surveying, improving accuracy and alleviating the need for more expensive surveying techniques. The correct implementation of geomagnetic referencing is particularly critical as we approach the increased activity associated with the upcoming maximum of the 11-year solar cycle. The DED observatory further provides an important service to scientific communities engaged in studies of ionospheric, magnetospheric and space weather phenomena.
The pdf file of this paper is in Russian. To purchase the paper in English, order SPE-166843-MS.
Construction solutions, construction technology and exploitation conditions of protection facilities, keeping the floating platforms at a designed location, are proposed in this scientific paper. They have been developed and proved by thermal calculation and strength prediction.
Protection structure includes a pile row, made of metal pipes, and special all-year cooling (freezing) devices, located inside the metal pipes. The piles are installed into the sea floor sediments or on the bedrock, depending on soil conditions. A compressor unit runs the cooling system during the construction on floating platform. The agent inside the cooling system is circulating which causes ice (in water) and ice-ground (below sea bottom) cylinders to grow around pipes. Ice cylinders form piles of big diameter. These piles may interlock fully or partially, forming a shockproof wall, which can withstand ice loads.
According to an expert forecast, over 25% of all unexplored petroleum reserves will be produced offshore, including Arctic shelf . Western Arctic offshore areas, such as Barents Sea, Kara Sea and White Sea, are the most potential. Ten oil-gas-and-condensate fields (OGFs) and two gas-condensate fields (GCFs) have been discovered over the last years. Four fields, such as Shtokman, Leningradskoe and Rusanovskoe OGCFs and Prirazlomnoe OGF, are gigantic.
Experience in design and exploitation of Arctic infrastructure is lacking. Natural and climatic conditions, ice conditions, ecosystem vulnerability, global warming, lack of available construction bases, etc. - all these factors are characteristic of the region being discussed. They require special technical design and new technological solutions on construction and exploitation stages.