Idemitsu Petroleum Norge a. s. acquired 15% of the Fram field from the Norwegian government in May, 2002. The Fram field is located approximately 20km north of the Troll C platform in the Norwegian sector of the North Sea in approximately 360m of water. The field contains several hydrocarbon accumulated structures and license holders have envisaged a step-by-step development of these reserves. In March 2001, the Norwegian government approved the 'plan for development and operation' of the Fram West field and development work was initiated. The start of production is scheduled on October 1, 2003. As of the end of May 2003, all development work has been on or ahead of schedule, including good performance of well pre-drilling operations. The biggest achievement is the successful drilling and completion of a dual-lateral well, in which the total horizontal sections reached more than 4, 900m. This adds to the operator Norsk Hydro's successful record of branch well operations in the North Sea.
Lufengl3-1 Oil Field is operated by JHN Oil Operating Company (JHN). It islocated about 250km the east south east of Hong Kong in a water depth of 145m and has beenproducing oil for about 10 years since October 1993. The current production rate is 12, 000 bopd. The field forms a dome shape anticline structure with gentle flanks and produces oil from highpermeable sandstone reservoirs with low gas oil ratio and strong bottom water drive. The 20th production well is drilled under the 5 th drilling campaign. Wells are developed fromstructurally high to flank positions with successive drilling campaigns. Horizontal wells (11 wellsout of all 19 wells) and Electrical Submergible Pumps (ESP) are adopted to maintain highproductivity and control water production The outline of the field and its development history are briefly reviewed and presented.
Industry seems to be in a frenzy of deepwater activity, especially in GOM, Brazil, West of Shetlands, West Africa, Australia, and Northern North Sea. However, a decade ago, in 1990-98, the oil industry was coping with low oil prices. Oil companies were rationalizing their portfolios. The GOM was viewed as the“Dead Sea”by many companies because of the high cost of deepwater development and the expectation of relatively low production rates. What a change we have seen in this 10 years. Early deepwater developments in the GOM with floating production systems were technical successes and synchronized started deepwater development BOOM. This paper also presents the BOOM and addresses several of the recent deepwater drilling RIGS.
In recent year, deep water drilling has become to go deeper area. It is not only oil and gas exploration, but also Methane Hydrate exploration and scientific drilling. In general, deep water drilling has a greater degree of difficulty than conventional drilling. Drilling fluid design issues include Shallow Water and Gas Flow (SWF, SGF), Narrow Operation Window, Gas Hydrates, Low Flow System Temperature and High Pressure situation, etc. Especially, shallow water/gas flow, gas hydrates, low temperature and high pressure situation are much related for drilling fluid. Drilling fluid design allow choice of Water Based Mud (WBM) and Oil or Synthetic Based Mud (OBM, SBM). Both systems had have solutions for conventional drilling so far. Not every ultra deep water well will present all of the issues wrote above, but many of them will be presented. Currently, solutions of SWF/SGF are using weighted mud, Remotely Operated Vehicle (ROV) and Annular Pressure While Drilling (APWD). WBM use Thermo Dynamic system to inhibit gas hydrates. However, it is needed that research and development of low dosage inhibitor as Kinetic Hydrate Inhibitor (KI) and Anti-Agglomerant (AA), toward much deeper.
More and more drilling occurs in frontier areas and particularly in deep water. In this environment, where the water depth often ranges between 1000 and 3000 m, the temperature at the seabed is extremely low, reaching 1 degC. In addition, a nonlinear temperature gradient in this water column and the sea currents further participate in and accelerate the cooling of the fluids in the wells. These low temperatures considerably slow cement hydration, which adversely affects the compressive strength development of the cement slurries. The young, soft formations encountered in the first few thousand meters below the seafloor preclude the use of normal-density cement slurries. However, conventional low density cements take a long time to set and develop significant strength at these very low temperatures. The daily rate of the rigs able to drill these deepwater wells is fairly high. In addition, the latest generation of offshore deepwater rigs is designed to work faster and deliver wells drilled more efficiently. It is therefore important to have lightweight cement systems that set quickly and develop high strength in the short period of time compatible with the operation of these new rigs. Often, the permeable layers below the seabed contain either free gas, when the water depth (and pressure) is reasonable, or gas hydrates at greater water depth. The lightweight cement system used in deepwater wells must therefore also control gas during its setting process at these low prevailing temperatures. This paper will address the selection of proper deepwater cement slurry. Several case histories are also presented, where lightweight cements capable of setting quickly and managing gas flow in low temperatures have been required to economically drill and case formations with low fracture gradient in deepwater wells.
In order to increase the share of primary energy supplied by natural gas and to augment the supply of domestically produced natural gas, Japan became active in the R&D area of Methane Hydrate Resource in the mid-1990s. Under the leadership of the METI, the “Nankai Trough” METI Exploratory Test Well, the “Collaborative R&D Studies on Methane Hydrate” and the drilling experiment in the Mackenzie Delta were conducted. Based on the results of these efforts, the “Methane Hydrate Exploitation Program” was newly announced in 2001, with establishment of the “Research for Methane Hydrate Resources in Japan” project as a means of putting that program into force. The “Research for Methane Hydrate Resources in Japan” is being conducted by the “Research Consortium for Methane Hydrate Resources in Japan”an organization comprised of the Japan National Oil Corporation (JNOC), the National Institute of Advanced Industrial Science and Technology (AIST) and the Engineering Advancement Association of Japan (ENAA) and the Japanese Industry. Under this arrangement, JNOC conducts resource assessment R& D, AIST advances production method R&D, and ENAA handles environmental impact assessment R&D. Since then, the first round of onshore production testing in the Mackenzie Delta, Canada was implemented as the joint international collaborative research in 2002. In the beginning of 2004, comprehensive drilling campaign is planned to clarify the accumulations of the resources in the Nankai Trough offshore Japan. The second onshore production testing in Alaska is also under planning. These undertakings have gradually clarified the issues in the area of drilling and completion technology that we should face and handle for further exploration and future development. Top-hole drilling technology in the deep water, horizontal well drilling and completion technology in the unconsolidated formation, offshore production testing methods specific to methane hydrate development are the issues to be investigated.
This paper reviews latest researches concerning the deepwater risers development. Offshore oil and gas development is moving into deepwaters and target water depth is becoming deeper year by year and the target at present moment is 2, 000m for production and 3, 000m for drilling. Innovative riser designs have been proposed and implemented. Steel catenary riser and its derivatives are typical innovations. Japan also has some research projects concerning the key technology development in this field. JAMSTEC is constructing a deepwater drillship for scientific ocean drilling program. Target water depth is 4, 000m or more and design and design philosophy are studied. One of other activities is development of Compliant Vertical Access Riser led by JNOC. CVAR utilizes catenary configuration and it can be used for production by FPSO. Technological challenges in deepwater riser development are handling of elastic response and utilization of reduced stiffness. Fatigue and collision are most important topics of deepwater risers. Development of analysis methodology of elastic response is reviewed. For drilling risers, analysis of dynamic behavior and its consideration in the design are key issues and latest research results are briefly introduced.
Geohistorical implications of several middle Eocene-lower Oligocene formations distributed in the western Hokkaido are restudied mainly from published data of foraminiferal assemblages. These formations are correlative to the Poronai and Momijiyama formations. Foraminiferal assemblages from the Utsunai and Magaribuchi formations in northernmost part of Hokkaido indicate paleobathymetric change from the upper bathyal to sublittoral zones. Those from the lower part of the Sankebetsu Formation in Chikubetsu-Haboro area indicate the shallower paleobathymetric zones than the upper bathyal zone, and those from the Shimokine and overlying Tappu formations indicate transgression from none-marine condition to the upper bathyal zone. These paleobathymetric changes and the geologic ages determined by calcareous nannofossil biostratigraphy show that the transgression which generated the Poronai Sea occurred from east to west and reached maximum depths in the late Eocene (CP 15b). Previous interpretation that paleo-topography of the Poronai Sea as an embayment can not be accepted, because there is no evidence that shallower bathymetric zones existed in the eastern part of this sea.
Living organisms are classified into three Domains of Bacteria, Archaea or Eucarya based on biochemical evidences by Woese et al. (1990). On this basis, all methanogens turn out to be archaea, not bacteria. Their cell membrane is characterized by grycerolipids of isoprenoids with ether-bonds, and some derivatives of these constituents are recognized as biomarkers of archaeal origin. Methanogens are autotrophic so that they can chemically assimilate inorganic carbon. CO2-reduction and decarboxylation of acetate are the two main reactions of methane generation, and unique coenzymes work on both. Marine environment is suitable for hydrogenotrophic C02-reductive methanogens, which live in symbiosis with H2-generative and other bacteria. On the other hand, the freshwater environment is favored by acetotrophic archaea. These two pathways are distinguished by the carbon and hydrogen isotopic compositions of accumulated methane.