This paper describes development of a cement slurry composition designed to cope successfully with gas migration problems. The gas blocking effect is obtained by addition of microsilica, a pozzolanic material of extremely fine particle size. Numerous tests have been performed under laboratory conditions to investigate the phenomena of gas migration through cements, and the corresponding amount of specially selected microsilica needed to effectively prevent gas flow. Introduction Gas flow behind casing after cementing has been a common problem in the industry since the inception of oil well cementing. After 1970 a comprehensive understanding of the mechanism involved in gas migration has been obtained through laboratory testing and field trials. Different concepts pertaining to solution of the problem have been suggested. Extensive reviews of literature on gas migration mechanism and methods to prevent gas migration up to 1985 have been given by Sutton and Faul and Cheung and Beirute. In Statoil's operation the need for gas tight cement was dictated by two frequently occurring phenomena in exploration and appraisal drilling in the Gullfaks field area, block 34/10 in the Norwegian North Sea: Gas migration through cement from a shallow gas zone outside 20" casing, and migration of gas from the paleocene and cretaceous formations outside 13 3/8" and 9 5/8" casings during the setting process of the cement. Both problems have presented serious, costly and time consuming consequences. In 1983 a research program was initiated to develop a lightweight gas tight cement for shallow gas problems. During the research period microsilica was found to have a suppressing effect on gas migration. Further study showed that provided a certain minimum dosage of microsilica was added, the slurry would exhibit gas blocking properties. The first field test with microsilica was performed in 1985, when 20" casing was cemented through a shallow gas zone. No gas migration occurred. Since this initial test, some seventy casing strings have been cemented with microsilica based slurries with density variations from 1.54 g/cm 3 to 1.95 g/cm3. A total success has been achieved by tailoring each slurry composition to adapt to existing field conditions. P. 641^

This paper outlines the technology and benefits of the continuous motion rig concept. This step change in drilling facilities technology is achieved through automation allowing any type of tubular to be pulled or run into the well without frequent intermittent stop in movement. The continuous movement is enabled by mounting two lift systems in the derrick. The two systems work together in sequence comparable to pulling or lowering a rope continuously with both hands instead of working with only one hand. To be able to work a string with threaded joints in a continuous fashion up or down in the well the joints must be disconnected or connected while in continuous vertical movement. This implies that slips and tong must be mounted on each of the lift systems, taking string weight while connecting or disconnecting the coupling. The basics and challenges of this system are outlined in the paper. When working in a continuous manner it is shown that even a slow continuous speed results in significant efficiency increases. A continuous slow drill pipe pulling speed of 0,5 m/sec results in tripping 1800 m/hr or app. 64 stands of 28m (app.90 ft) stands per hour. Doubling the speed to 1 m/sec, corresponding to app.peak pulling speed of today's drawworks in low gear, results in tripping speed of 3600m/hr. One challenge of the system is to have technology in the vertical moving tongs to break connection and spin out in short enough intervals to avoid excessive height in the derrick. Since string load is taken by the lift system off well center bending loads will be transferred to guide beams which must be given proper strength. Other benefits of the continuous movement is minimizing problems normally connected with surge and swab effects due to lifting drill pipe out of slips and increasing pulling or lowering speed to peak and then brake down and stop. Further the problem of stuck pipe or casing caused by stop for connection is eliminated.

The basic principles for a Continuous Motion Rig (CMR) has been presented earlier (IADC/SPE128253).The CMR concept allows jointed pipe to be run or pulled in a continuous manner. Several benefits besides significant improvement in tripping speed results from continuous movement of pipe. This new rig concept can be used on all rigs –on or offshore where well costs, well safety and efficiency are important issues. The CMR concept based on a 750 ton system has been studied in a Joint Industry Project (JIP). This paper discusses aspects of the Continuous Motion Rig such as system benefits, equipment, control system and layout based on findings in the Joint Industry Project. Design basis in JIP was set at 3600 m/hr trip speed corresponding to 1 m/sec continuous running or pulling of drill pipe. High efficiency demands a fully automated rig as concerns surface processes involved in normal drilling operations. This automation requires rethinking control systems. Continuous motion technology opens up possibilities to explore and exploit deeper deposits economically.

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Drilling automation is gaining momentum and is a topic of high interest in the drilling community. In present drilling operations automation is still in its early phase. Several technology gaps have to be closed. Use of technology to automatically identify various equipment and tools used in the drilling process and automatically deliver this data to control systems and to real time predictive modeling equations is considered to be a key enabler in drilling automation.Radio Frequency Identification (RFID) for drill pipe has been developed to withstand temperature and shock/vibrations encountered in most wells. This paper outlines the technology development of RFID tags and status for application on drill pipe. Key challenges have been temperature limits, vibrations, wear and max tripping speed to pick up radio signals. Further the paper outlines present software applications and future possibilities in software development using RFID data as input. It will be presented how RFID helps in avoiding drill pipe failures, and how RFID will be used as an enabler in the future in drilling automation, predictive modeling and in real time decision making.