Slimhole technology recently has been established as a proven alternative to conventional drilling operations. Now that the drilling community has shown that slimhole can reach the objective and is both technically and economically feasible, completion and production aspects of small wellbores receive the focus of increased attention. This paper discusses influences of the drilling process on later production performance of the well and focuses on currently available completion systems. A critical comparison between conventional drilling systems and their formation damage potential with slimhole-specific characteristics is given. Questions concerning production and workover strategies that sometimes are considered to be a barrier when deciding whether to apply or reject slimhole technology are presented. Economic justifications for selecting slimhole solutions during the drilling phase of the well are critically weighed against the impact of possible production impairments during the total well life cycle. Introduction Slimhole drilling technology has repeatedly gained and lost interest among the international exploration community, primarily as an alternative for remote, harsh or economically constrained drilling operations. Hardly was the question of producing from slimhole wells or even drilling development projects in a "slim" configuration ever addressed. Almost reflecting the cyclic nature of the oil and gas business in general, the last "hump" of slimhole interest started as early as 1955, sparking off several publications and general interest throughout the industry. Hinckley, in a 1960 paper, stated that" … slimhole completions have come a long way since the early days of 2-in. line pipe at 1,000 ft in a 'poor-boy' type operation. Techniques and equipment have now been developed which make it possible to use 2-7/8-in. or smaller casing in completing the majority of the wells now being drilled. As additional operators realize that this more economical method of well completion is time proved and need not be limited to 'special situations', its usage will continue to increase…". Still, during the early 1960s, slimhole drilling interest faded out, only to re-surface in the mid 1980s, when Macfadyen, et al., report on a slimhole exploration project in Irian Jaya, Indonesia. Remote locations with difficult access and helicopter transport capability again made slimhole the method of choice. Hoffman and Lawrence in their 1986 paper report on slimhole successes in adding reserves by deepening shallow wells, cementing 2-7/8-in. production tubing in place inside a 3-7/8-in. new open hole section. Perforating and even hydrofracing through the cemented tubing are reported, and the project has been quantified as both technically and economically successful over a period often deepening operations. P. 705

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Formation and fluids evaluation of heterogeneous and over pressured retrograde gas condensate low-permeability but high-reserves potential reservoirs requires use of advanced formation evaluation techniques. The Achimovskaya formation of Urengoiskoe field is one of Russia's giant low-permeability gas condensate fields. The main objectives of the pilot phase of the exploration projects in the Achimovskaya formation are reducing reservoir and fluid uncertainties, confirmation of technical and commercial feasibilities, construction of a pilot gas processing plant (UKPG), and startup of a pilot gas and condensate production. The initial formation evaluation in the first two "Achimgaz" vertical wells included an extended formation logging suite followed by formation testing and downhole PVT sampling achieved using a wireline formation tester (WFT) that had a dual packer to test a large area of open hole. Formation testing and sampling objectives were: reservoir evaluation, formation pressure profiling, direct measurements of mobility (effective permeability), downhole PVT sampling for hydrocarbons confirmation, and full laboratory studies of formation fluids before the production phase of the field. Rig time constraints were one of the main issues for the extended formation evaluation program, defining logging and testing scope. In addition to traditional downhole sampling methods like low-shock PVT sampling (which allowed taking gas samples above the dewpoint), new approaches for logging and testing techniques were applied for the first time in Russia during this job. These were the combination of inflatable straddled dual packer wireline formation tester with nuclear magnetic resonance (NMR) logging in a single logging string and the use of two downhole pumps, also in a single string. The quality of sampling was controlled by application of downhole fluid analysis techniques. Comprehensive pre-job planning, close cooperation with drilling and operating companies' representatives, and real-time decision-making during data acquisition led to the successful completion of the operation. This paper describes this first successful application of a dual-packer wireline formation tester to obtain PVT samples of retrograde gas in the Achimovskaya formation. As a result of the job, the presence of hydrocarbons was proved, formation pressure and mobility profiles were obtained along the tested sublayers of Achimovskaya formations, and high-quality PVT fluid samples were acquired. This provided valuable information for future testing, appraisal drilling, and field development planning. Furthermore, comparison between core permeability, formation testing fluid mobilities, and NMR permeabilities acquired in one of the exploration wells is also shown in the paper.

Today's rigsite information acquisition systems are demanding to the operator, costly to install and maintain and hardly friendly to inter-company networking interests. Cost-efficient solutions, integrating rigsite instrumentation with drilling data acquisition through sensor telemetry, daily drilling reporting and all additional related information services (e.g. cement job records, well logs, well tests etc.) are clearly wanted by the drilling community to enhance quality control. The paper lists experiences gained with extensive drilling rig instrumentation and drilling process information gathering systems over a period of 12 months, critically evaluating the quality and usefulness of commonly acquired drilling data as well as the actual application of such information volumes in accelerating the drilling learning curve and enhancing process and quality control. A detailed description of storing "streamed" drilling data into a large-scale multi-user relational database and the additional value of such information volumes available to the user "at his fingertips" is presented. The realization potential of such systems on low- to medium-cost on-shore drilling operations as well as the possible integration of multi-well and multi-rig systems and the buildup of field- and area-databases are presented from a service-company as well as operator standpoint. A definition of the current state-of-the-art in rigsite information management is attempted and the future potential for such systems is assessed. Introduction Data volumes originating at the wellsite are mostly grouped together as "mud logging" or "reporting" data. When taking a closer look at the information sources distributed throughout the process of drilling and completing a well, several - sometimes redundant - origins can be defined that in many cases don't even find their way into a final, comprehensive well summary. While conventional "mud logging" or daily drilling reports are stored in a final well "file" (sometimes literally in a storage room file cabinet), the integration of all wellsite information sources into a manageable, digital form for easy storage, retrieval and later analysis should be the target for comprehensive rigsite information management procedures. Data is valuable. Purging acquired data at the end of a drilling operation is in fact destroying resources that - if stored properly - can provide a valuable basis for later evaluation and/or planning of other operations. Today's information management platforms should provide a structure suitable for integrating all information sources, e.g.–well planning and engineering background (wellpath designs, drilling/casing programs, drilling fluid and hydraulics selection, planned cost structures etc.) - measured operating parameters throughout the drilling and completion phase of the well ("streamed" data from instrumentation or mud logging providers) - third-party service company records (MWD/surveying data, casing running records, cementing job records, geophysical well logs etc.)–geological information, both from the planning phase and actual cuttings sampling information from location, including gas monitoring and drilling fluid characteristics reporting throughout the drilling phase - rig inventory or consumables as far as they are of interest to the operator (chemicals, drinking/industrial water, fuels, solids control equipment such as screens/cones etc.) P. 697