Africa (Sub-Sahara) Eni started production from the Nené Marine field, which sits in the Marine XII block in 28 m of water, 17 km offshore the Republic of the Congo. The first phase of the field produces from the Djeno pre-salt formation, 2.5 km below the ocean floor at a rate of 7,500 BOEPD. Future development will take place in several stages and will involve the installation of more production platforms and the drilling of at least 30 wells. Eni (65%) is the operator with partners New Age (25%), and Société Nationale des Pétroles du Congo (10%). The well's primary target is the Bunian structure: a four-way, fault-bounded anticline, which was defined by a 3D seismic survey. It will be drilled to a total depth of 1682 m.
Eight of the world's 10 longest wells have been drilled by ExxonMobil as operator of the Sakhalin-1 project in Russia. Components and drilling tools involved in the well design are evaluated and redesigned throughout the program to maximize penetration rate and reduce flat time. Drillstring-torque capacity was recognized as a limiter for increasing penetration rate and for reaching total measured depth capability. The operator consequently sought an alternative drillpipe connection with higher torque capacity. The Sakhalin-1 project comprises the Chayvo, Odoptu, and Arkutun Dagi fields off the east coast of Sakhalin Island, Russian Federation.
Recently there have been delivered and designed new icebreakers, icebreaking shuttle tankers, container vessels and LNG carriers. Many of these vessel concepts are relying on podded propulsion system. Azipod propulsion has been selected to many of these vessels as it provides excellent ice performance for the vessel, good torque characteristics for the propeller and there already exists proven track record of ice operations. Currently the demand for even bigger icebreaking vessels with higher capacity is increasing. Due to increasing market need ABB Marine have further developed Azipod propulsion concept to meet the demands of arctic ice classes and power requirements of more than 15 000 kW per thruster unit. This paper will give an overview of 25 year of development of azimuth podded propulsion, Azipod, for icebreaking vessels and introduce latest breakthrough projects in arctic shipping.
Description: The Sakhalin-1 project, operated by Exxon Neftegas Ltd., is located offshore Sakhalin Island in remote Eastern Russia and includes three oil and gas fields – Chayvo, Odoptu and Arkutun Dagi. The drilling and completion related technical and operating challenges of the Sakhalin-1 project are many. The project has relied heavily on Extended Reach Drilling (ERD) and robust completion technologies to simplify the operations, maximize capital efficiency, and minimize the environmental footprint.
ERD operations at Sakhalin-1 have required a balanced engineering / operational approach – built upon a thorough understanding of the physical complexities, the insight to provide robust technical solutions, and the operational expertise to implement them efficiently, safely and without environmental incident. Up-front identification of technical and operational limiters of the well plan is critical. Once limiters are identified, engineered solutions are designed, tested and implemented. Technology, innovation and the transfer of knowledge into the operation are critical success factors. This process requires an innovative engineering and support structure with deep technical capabilities that is also conducive to the creation and implementation of new techniques.
Undergirding the project is a basic set of operating principles that includes safety, protection of the environment, maintaining the highest standards of business controls, and compliance with applicable laws and regulations.
Efficiently drilling and developing resources while redefining the ERD envelope at Sakhalin-1 requires a solid understanding of the physics involved, and the insight to identify and employ innovative technologies with careful attention to up-front engineering and operational detail. This paper will highlight some of these challenges as well as describe some of the innovative techniques and technologies that have unlocked the Sakhalin-1 resources.
Garfield, Tim (ExxonMobil) | Streltsov, Tim (Rosneft) | Erratt, Duncan (ExxonMobil Upstream Research Co.) | Kissling, Randy (ExxonMobil Development Co.) | Abreu, Vitor (ExxonMobil Exploration Co.) | Goulding, Frank (ExxonMobil Production Co.)
In the last decades, many discoveries and field developments have been made in deepwater plays around the globe. Important lessons learned in more mature areas like the North Sea and the Gulf of Mexico – have been applied to more recent ventures worldwide. This presentation highlights technical learnings that supported success in these plays and application opportunities in Russia.
In West Africa, over 22 billion oil-equivalent barrels were discovered in deepwater reservoirs in less than 20 years. This exploration success was due to the presence of robust petroleum systems, high quality reservoirs and efficient technology development and application. The Congo Basin and Niger Delta deepwater play areas were identified as active, oil-prone hydrocarbon systems and reservoir-prone long before any discoveries were made; under-scoring the importance of regional analysis. In these basins, companies entering the correct areas early captured most of the value. Exploration success rates were highest where 3D seismic was used and hydrocarbons could be directly detected. Many deepwater exploration discoveries have significant reservoir and trap complexity. With long construction lead times and high capital costs, early and accurate subsurface models are needed to deliver profitable deepwater developments. Subsurface characterizations leveraging highquality 3D seismic, more accurately predict reservoir and seal architecture. Fundamental understanding of deepwater depositional processes is a key enabler, especially when supported by an active research program.
Later in production life, 4D (time-lapse) seismic, integrated with field surveillance data and history-matched reservoir models have been instrumental in identifying un-swept hydrocarbons and in-fill or re-development opportunies, resulting in increased hydrocarbon recovery.
In Russia, Sakhalin Island and the Black Sea are areas with established and emerging deepwater exploration and development opportunities. Application of key learnings from a broad global experience base will aid exploration and help ensure profitable deepwater developments.
The processes for finding, developing and producing oil and gas from deepwater reservoirs are different from other reservoir types in significant ways. First, often the environment in which these reservoirs form is the same in which they occur today – very deep water. There are many challenges associated with economic development of petroleum resources located in deep water. Robust risk and mitigation plans are needed due to the high cost environment and limited capability to recover from or drill out of subsurface “surprises”. A second significant difference is that many deepwater clastic reservoirs, from slope channel to basin floor fan deposits, tend to have very complex reservoir and seal architecture which can be manifested during development and production by significant issues with reservoir connectivity and compartmentalization. Higher levels of geologic definition are often required.
Description of the Paper
Seven of the world’s ten longest wells by reach and measured depth have been drilled by ExxonMobil as operator of the Sakhalin-1 project in Russia. Drilled from shore by one of the largest and most powerful land rigs in the industry, wells extend horizontally under the sea floor approximately 11 kilometers (7 miles). Using the Operator’s redesign methodology, post well reviews are conducted after each well is drilled and completed to identify the key limiters to drilling performance. All components and drilling tools involved in the well design are evaluated and re-designed throughout the drilling program to maximize penetration rate and reduce flat time. This paper will provide an overview of how drill string torque capacity became a limiter to increasing penetration rate and kept the Operator from extending their total measured depth capability. This limiter necessitated that the operator seek an alternate drill pipe connection with higher torque capacity. The design of the new drill pipe connection and results to date from field implementation will be presented.
The drilling tubular connection evolution described in this paper highlights the need for continuous technology development to further increase the Extended Reach Drilling (ERD) envelope.
Results, Observations and Conclusions:
Utilizing an evolutionary connection design allowed interchangeability with existing drill pipe, accessories, and tools while providing 26 percent more torque capacity. Comparative fatigue testing demonstrates that the design will provide equal or better fatigue life when compared to the existing connection even while operating at a higher stress level. Deployed for approximately one year, initial field performance of the new connection has allowed the Operator to drill with higher continuous drilling torque while maintaining compatibility between the new and old drill pipe connections.
Significance of Subject Matter:
ERD has become a commonly used technique to economically access reserves using existing infrastructure. A key ERD drilling challenge is the large amount of friction imposed by the wellbore on the drill string that results in high torque. Technologies that increase overall system torque capacity allow the Operator to drill farther and access more reserves.
Description of the Paper:
The second drilling campaign at the Chayvo field, located offshore Sakhalin Island, targeted the development of a new reservoir zone using extended reach wells from onshore. A total of 4 oil producers and 1 gas injector were planned to develop the northern portion of the reservoir. To effectively drain the east and west flanks of this reservoir, record length wells beyond the current ERD envelope were required. Key challenges included high torque and drag, wellbore positioning in a thin oil column, wellbore stability, long horizontal completions, and downhole tool telemetry. This paper describes the Operator's experience with drilling these challenging wells that resulted in several new ERD records. Key well design features, equipment upgrades, and redesigns based on lessons learned will be discussed.
The case history described in this paper illustrates that the advancement of the ERD envelope is possible through detailed planning, technical design, and operational excellence.
Results, Observations and Conclusions:
The planning of these wells built upon the Operator's previous ERD experience along with additional tools and techniques. Three of the project wells set new worldwide ERD records for measured depth; the longest well, Z-42, established new records for measured depth (12,700m) and horizontal reach (11,739m). Completion designs were optimized to successfully run a 3,600m long open hole completion, and the well was finished in ~70 days. As a result of this successful development, additional wells are being planned in conjunction with technology advancement initiatives that will push the ERD measured depth envelope to 13km.
Significance of Subject Matter:
Extended reach drilling (ERD) is an established technique to economically access reserves from existing infrastructure, reducing the need for additional drill centers and consequently reducing the drilling and facilities environmental footprint. Continuing advancement of the reach envelope along with delivering cost-effective wells will further maximize the benefits of this technique.
A major part of world’s oil and gas reserves are located in Arctic and Subarctic seas, such as Sakhalin fields in Okthosk Sea as well in Chuchki Sea, Beaufort Sea Alaska. Year around operations in these areas results increasing need for special designed icebreaking offshore support vessels and tankers. Important characteristic of these vessels is the capability in ice managent duties.
Azimuth thruster offers great flexibility in different ice management using the thruster wake and propeller close contact with ice. Electric propulsion with Azipod propulsors has been used in such vessels with good success for many years and the system itself has shown to be reliable and very good characteristics when operated in ice. In Sakhalin region there has accumulated experience from 7 icebreaking vessels with ABB electric propulsion many equipped with Azipods. Recently two new icebreaking vessels with Azipod have been built for Arkutun-Dagi field. Electric Azipod propulsion system have been playing an important part in several arctic ship projects making the demanding projects technically and economically feasible. In this paper will be presented characteristics as well some full-scle test results where Azipod units are used in ice management type operations.
Li, Huailiang (Offshore Oil Engineering Company, Limited) | Yang, Yun (Offshore Oil Engineering Company, Limited) | Yuan, Ruhua (Offshore Oil Engineering Company, Limited) | Xie, Weiwei (Offshore Oil Engineering Company, Limited) | Wang, Alan (Offshore Oil Engineering Company, Limited) | Jin, Xiaojian (China National Offshore Oil Corporation)
This paper describes the design functionality and structural integrity of the T-Shaped barge hull modification of launch barge HYSY229 in depth. The T-Shaped hull has to be reinforced to comply with both regulation and project strength requirements by adding internal longitudinal bulkheads and increasing thickness of deck and bottom plating. The challenge of the hull modification is to ensure a floatover installation capacity of 30,000Te integrated topsides while maintaining its original launch capacity of 30,000Te jackets.
The Sakhalin-1 project comprises the Chayvo, Odoptu, and Arkutun Dagi fields off the east coast of Sakhalin Island, Russian Federation, as shown in Figure 1. Development drilling at the Chayvo field started in 2003 with extended-reach wells drilled from an onshore wellsite pad with the Yastreb drilling rig. In 2005, further development drilling commenced from the offshore Orlan platform. In 2008, the Yastreb rig was moved approximately 75 km north to the Odoptu onshore wellsite pad and drilled nine ERD wells as part of the initial-stage development of Odoptu. Following the Odoptu campaign, the Yastreb rig was moved back to the Chayvo onshore wellsite in 2011 for further development and infill drilling of the Chayvo reservoirs.