In this paper we present data from several offshore wells, which have experienced wellbore stability related problems, especially over intervals with higher angles of deviation. We performed a wellbore stability evaluation for several angles of deviation using log, core and drilling data from all the existing wells, in order to predict the optimum drilling parameters to be used in the next wells to be drilled in this area. The answers provided by this study included properties such as, recommended mud-weights (minimum & maximum) as a function of angle of deviation, rock strength, and pore pressure. The determination of the rock strength along with the optimum mud-weight windows improved overall the drilling performance by minimizing washouts, loss of circulation, and optimizing casing design by elimination of unnecessary casing strings. Moreover, improvement of bit performance was achieved by using the predicted rock-strength values. As a result, drilling time and well construction costs were reduced significantly.

Fossil fuel fired plants are responsible for the one third of the carbon dioxide (CO2) emissions which thought to be a major contributor to the current rise in the Earth's surface temperature. Reducing CO2 atmospheric concentrations by capturing emissions at the source---power plants or chemical units---and then storing them in subsurface reservoirs is thought by many scientists to be a reliable solution until emission-free energy sources are developed and viable. The current options for captured CO2 utilization are; Enhanced Oil Recovery (EOR), Enhanced Coal Bed Methane Recovery (ECBM), Enhanced Gas Recovery (EGR), Food processing applications, Mineral products, Fertilizer manufacture, Algae growth promoter, Enhanced plant growth. The capture and storage of CO2 continues to accelerate as new projects are initiated and existing projects confirm the development scenarios. A crucial element in CO2 storage is reliable monitoring of CO2 migration behavior and storage volumes. An innovative seismic monitoring techniques, has recently been awarded a U.S. Department of Energy (DOE) project that will examine the application of time-lapse (4D) seismic technology and advanced reservoir simulation to optimize CO2 EOR operations. Well design, cementing, completions techniques and long life cycle mechanical integrity assurance are currently subject of many R&D projects. Industry expertise also is being tapped in CO2 projects across Europe and in Australia, including four major EU proposals under the Framework Program Six and the Australian CO2CRC Otway Project. These projects address pertinent issues in CO2 capture and storage such as site selection, storage monitoring and verification techniques, developing local CO2 storage sites from hydrogen- and power-generation plants, and industry training. In our paper framework of CO2 sequestration and vital aspects such as; site selection, reservoir characterization, modeling of storage and long term leakage monitoring techniques will be illustrated. Introduction The prospect of global warming is a matter of genuine public concern. The concentration of carbon dioxide in the atmosphere has been increasing since industrialization in the 19th century, and consensus is forming that mankind is having a visible impact on the world's climate. It is generally acknowledged that the most important environmental impact of fossil fuel burning is an increased global warming from the buildup of greenhouse gases in the atmosphere. This warming occurs when the added greenhouse gases trap more of the earth's outgoing heat radiation. There is a wide consensus from extensive research in the last three decades that rapid climate change is already happening, that global average temperatures are increasing at unprecedented rates. In parallel, CO2 emissions from anthropogenic sources have also been increasing in the same time frame and these are known to produce a greenhouse effect. The greatest contributor to global warming over the past century has been carbon dioxide, mostly from deforestation and fossil fuel burning. Methane is second and arises from coal deposits, leaking natural gas pipelines, landfills, forest fires, wetlands, rice growing, and cattle rising. Nitrous oxide, also known as "laughing gas," is third and arises from agricultural practices, fuel burning and industrial processes (Figure 1). The foremost contributor to increased atmospheric CO2 is fossil fuel combustion for power generation, transport, industry, and domestic use. Energy from fossil fuels has provided a high standard of living in industrialized countries and the demand for energy continues to grow as developing countries seek to raise their standards of living.

A practical procedure is presented for determining the radius of the thawed-permafrost region around a well and finding the temperature distribution in that region. Such information is important in drilling, completion, and production operations in Arctic regions. A new numerical method was developed and used in a computer model to generate solutions for radial thawing of permafrost with axial symmetry, which was shown to be a function of three dimensionless parameters plus dimensionless radius and time. The model parameters plus dimensionless radius and time. The model generated solutions for the range of values of the three parameters for conditions in Alaska's North Slope. The dimensionless radius of the thawed-permafrost region was related to dimensionless time through a simple power-law equation containing two constants. Results generated by the computer model were used to develop correlations giving the relationships between the two constants and the three parameters. The correlations can be used to find the thawed-permafrost radius, and once this information is available, the temperature distribution in the thawed region can also be calculated. For the correlations, the temperature at the well was assumed to be constant. In more realistic situations in which well temperature varies with time, we also describe a simple method of calculating the amount of thawing. OPERATIONS IN ARCTIC POSE NEW PROBLEMS FOR OIL INDUSTRY One of the problems associated with oil-field operations in Alaska is thawing of permafrost around producing oil wells. In such wells, the heat from producing oil wells. In such wells, the heat from well fluids will gradually thaw the permafrost. The thawing may destroy the bond between the cement and the permafrost, cause instability and subsidence of the soil around the well, and place high mechanical stresses on the casing. To prevent damage to the well, permafrost thawing is typically controlled by insulation, refrigeration, or insulation of the top several hundred feet of the well, while the rest of the permafrost is allowed to thaw uncontrolled. Whatever type of preventive measure is used to avoid damage to the well, we need to know the thermal behavior of permafrost in order to design an economic well completion for avoiding thawing problems. In particular, we would like to be able to forecast the particular, we would like to be able to forecast the rate of advancement of the thawing front and the temperature distribution in the thawed-permafrost region under a given set of conditions. Such a forecast requires the solution of one of the classic nonlinear heat-transfer problems known as heat conduction with phase change, or the Stefan Problem. The common feature of Stefan Problems is Problem. The common feature of Stefan Problems is the existence of a moving interface separating liquid and solid phases. The thermal properties of the two phases differ on either side of the moving interface, phases differ on either side of the moving interface, where heat is released or absorbed. Depending on the relative temperature gradients of the two phases, the interface moves either into the solid region (melting) or into the liquid region (solidification). The position of the moving interface is to be determined as a position of the moving interface is to be determined as a function of time, along with the temperature distributions in the liquid and solid regions. One of the first important works that examined the amount of thawed permafrost around producing oil wells was published in 1970 by Couch et al. They used an implicit finite-difference scheme to solve the equations resulting from the weak formulation of the Stefan Problem. The weak formulation assumes that melting or solidification takes place in a temperature interval (for more details see Atthey), rather than at a specific temperature (e.g., 0C (32F) for water), as assumed in the classic formulation. Couch et al. studied the effect of insulation on the radial-vertical heat conduction with phase change around producing oil wells. P. 643

A practical procedure is presented for determining the radius of the thawed-permafrost region around a well and finding the temperature distribution in that region. Such information is important in drilling, completion, and production operations in Arctic regions.

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