Taking fluid losses in a drilling operation is common practice. Pumping loss-circulation material (LCM) to control drilling fluid losses to the formation is part of the overall solution. Precisely spotting the correct volume of LCM and protecting sensitive directional tools in the bottomhole assembly (BHA) has proven to be a considerable challenge.Recently in a critical offshore well in the North Sea, the 6.5 intermediate section was drilled to 10,446 feet through a soft, porous limestone formation. In addition to the propensity of the chalk formation for seepage, a pre-existing natural fault was also present. The drilling fluid used to drill this section was 8.7-ppg paraffin-and mineral-based mud. Factors key to controlling losses were LCM displacement in precise intervals of the section and timely delivery of the material into the well annulus through a diverter circulation sub. High flow rates and minimal differential pressure at the tool were key to the mud program.Because the RFID-enabled diverter circulation sub was capable of being selectively opened and closed using specifically programmed transponders, it did not require a ball seat or mechanical indexing system. This feature, coupled with the extra-large total flow area (TFA) and integrated flapper system of diverter circulation sub, allowed precise and timely LCM pumping while completely protecting the measurementwhile-drilling (MWD) and rotary steerable (RSS) systems from damaging debris.A total of 29 pills were pumped in the 14-day period that it took to drill the section. The circulation sub was strategically opened and closed in the diverting mode during this pill and LCM pumping program to control losses and allow the operator to drill ahead. By using an RFID-enabled circulation sub specifically designed to displace heavy pills and LCM, the operator was able to control losses, maintain proper hydrostatic pressure, and reach total depth (TD).

The handling of drilling jars can present safety hazards when they are being serviced, transported, loaded or unloaded, handled on the rig floor, run in hole or racked in the derrick. Dangers are especially prevalent if the drilling jar is not equipped with a mechanical locking device. These tools present a potential hazard to personnel because of the possibility of inadvertently activating the jar. Previously, this issue has been addressed by using an externally installed clamping device which is attached to the jar to lock it open and prevent an unplanned activation. If the clamping device is not properly installed, it can become a dropped object hazard. In response to the potential hazard of a dropped object from the derrick, some drilling contractors have elected to lay out jars from the Bottom Hole Assembly, BHA, on every trip. This in itself adds time to the operation and additional exposure to personnel. The drilling jar safety clamp has evolved in design and material selection. The industry has evolved to a composite design, which reduces the element of operational error thus reducing the chance of a dropped object in the derrick and improved handling. The composite design is much more reliable and easier to handle but has failed to eliminate the dropped object hazard. Following extensive risk analysis of the existing clamp, an innovative approach has been conceived in the form of an internal latch mechanism which can eliminate the requirement for an external clamp and provide more effective control of the jar while eliminating a possibility of an object being dropped in the derrick. In this paper, the authors will review the safety hazards associated with the handling of drilling jars. They will describe the evolution of the external clamp, which is the main device in use. The paper concludes with a detailed discussion of the internal latching device that has been developed in the continuing effort to enhance the safety of drilling operations. Introduction Drilling jars provide a means of supplying a powerful upward or downward force to a stuck drill string. Mechanical jars are preset to a specific load for activation in the repair and maintenance center while the force for hydraulic jars varies with the applied load from the drill string. In vertical or low inclination wells, both types of jars should be run in the well in tension, which is mandatory for mechanical jars and advisable for hydraulic jars. Where inadvertent cocking and subsequent activation of the jar can occur such as in directional wells, jars can be run in compression. A jar should be handled with care in all aspects of every operation, from assembly and testing, to transportation to and from the rig location, picking up, to running in the well, racking back in the derrick, or laying the jar down when no longer in-use. The possibility of inadvertent cocking and subsequent unexpected activation of the jar can present a hazard to personnel and other equipment. Of the various operational situations which may occur, perhaps the most dangerous is when the drilling jar is racked in the derrick. It is extremely important that when racking the jar in the derrick, the jar is positioned at the top of the stand of drill collars or heavy-weight drill pipe with the mandrel clamp installed. If this maxim is not adhered and the jar is racked at the bottom of the stand without a mandrel clamp, the weight above the jar can cause the jar to energize and create a force which could dislodge the stand from the derrick and fall to the drill floor.

The handling of drilling jars can present safety hazards when they are being serviced, transported, loaded or unloaded, handled on the rig floor, run in hole or racked in the derrick. Dangers are especially prevalent if the drilling jar is not equipped with a mechanical locking device. These tools present a potential hazard to personnel because of the possibility of inadvertently activating the jar. Previously, this issue has been addressed by using an externally installed clamping device which is attached to the jar to lock it open and prevent an unplanned activation. If the clamping device is not properly installed, it can become a dropped object hazard. In response to the potential hazard of a dropped object from the derrick, some drilling contractors have elected to lay out jars from the Bottom Hole Assembly, BHA, on every trip. This in itself adds time to the operation and additional exposure to personnel. The drilling jar safety clamp has evolved in design and material selection. The industry has evolved to a composite design, which reduces the element of operational error thus reducing the chance of a dropped object in the derrick and improved handling. The composite design is much more reliable and easier to handle but has failed to eliminate the dropped object hazard. Following extensive risk analysis of the existing clamp, an innovative approach has been conceived in the form of an internal latch mechanism which can eliminate the requirement for an external clamp and provide more effective control of the jar while eliminating a possibility of an object being dropped in the derrick. In this paper, the authors will review the safety hazards associated with the handling of drilling jars. They will describe the evolution of the external clamp, which is the main device in use. The paper concludes with a detailed discussion of the internal latching device that has been developed in the continuing effort to enhance the safety of drilling operations.

Well cleanup operations require high fluid-circulation rates for efficient cuttings transport and hole cleaning. Conventional circulation subs are deployed in drilling applications such as slim-diameter wells to deliver higher circulation rates and cuttings removal. But because these subs require multiple trips downhole for mechanical or hydraulic actuation, they add rig time and costs while drilling complex, high-angle wells. This paper reviews a radio frequency identification (RFID) circulation sub that facilitates hole cleaning via remote actuation. The RFID circulation sub is actuated using commands communicated by RFID tags as they pass through the inside diameter (ID) of the tool string, which replaces conventional actuation methods such as ball drop or darts. This sub can be selectively actuated any number of times during the same trip downhole for enhanced operational flexibility. And because no ball seats are present, the sub maintains a full-bore ID that facilitates higher annular velocity and turbulent flow. This paper also reviews a field application in which the RFID sub was deployed in a multi-assembly tool string to clean out a perforated 7-in. liner section and cased-hole section for a North Sea well. Once the well reached total depth, the sub was opened, closed and reopened a number of times, on command, to facilitate hole cleaning and increase fluid circulation rates to remove the wellbore debris. The RFID circulation sub helped deliver a cleaned and conditioned hole that was ready for stimulation. By completing the entire operation in a single trip, the operator saved 1.5 days of rig time.