For years drillers have been taught to mitigate all vibrations in the drillstring while drilling to maximize Rate of Penetration (ROP), limit bit damage, and extend bit life. While limiting lateral vibrations and stick/slip are proven ways to improve performance and maintain directional control, in recent years it has been conclusively proven in the field that inducing axial agitation with specialized downhole tools can significantly improve lateral reach. Currently, however, the benefits of downhole oscillation tools have not been thoroughly studied for other performance gains, such as improved ROP in non-directional wells.An extensive research study, including lab and field testing, found that a low-frequency, benign axial vibration can increase the ROP significantly in all well types. Initial laboratory experiments were performed by inducing axial vibrations into the drilling process on a small scale drill bit in hard rock. Dramatic improvements in ROP and drilling efficiency were observed, with the added benefits of improved bit life and an unexpected reduction in stick/slip. This lab experiment was later tested in the field by utilizing a proven downhole oscillation tool in an active Bottom Hole Assembly (BHA) to create the effect that was simulated in the lab. The field tests showed the same results as the lab tests: significant performance gains were observed in several test wells using the downhole oscillation tool as compared to offset data. In addition, this same downhole oscillation tool showed drastically improved directional control when run above a Rotary Steerable System (RSS) tool, and stick/slip was practically eliminated with no negative effect on bit life or BHA reliability.High-speed sensor data collected at the bit during both the lab and field tests will further demonstrate the validity of the theory. Testing for a hard-rock application with roller cone bits is forthcoming, as the data indicates possible performance gains in this environment as well.Overall, the study revealed many benefits, such as improving well placement, reducing Non-Productive Time (NPT) and time to Total Depth (TD) by preventing BHA component damage through beneficial axial vibrations from the downhole oscillation tool. The data indicates that "benign vibration" can drastically improve drilling performance. Induced Vibration Theory and Application Background (Forster and Grant, 2012)Theoretically, any drilling assembly which provides a fluctuating axial load application focused downhole will improve drilling efficiency. The axial excitation will improve drilling efficiency by breaking static friction, both in the BHA and at the bit. Once static friction is overcome and stead-state dynamic friction results, the Weight on Bit (WOB) required will be a fraction of the WOB required under normal drilling conditions, and load transfer will improve.
While jar technology has been used in the oil industry for the better part of the last century, the basic function and capability has not taken many leaps forward. Increasingly complex well geometry and deeper target depths continue to push drillers into tighter, higher risk well conditions that raise the probability of stuck pipe events. As demand for hydrocarbons has forced our drilling capabilities to evolve, the increased risk associated with these wells has forced the evolution of jarring technology to drastically evolve. By assessing the critical needs of the industry, a jar has been designed to operate in the harshest environments, with superior reliability, and the highest firing loads available to increase the levels of success in freeing a drill string during a stuck pipe event. Every pound of impact force delivered is critical to improve the chances of retrieving the drill string safely to surface and this new technology has raised the standard force by as much as 20%. While the operation of this innovative technology remains consistent with industry standards, the performance in regards to torsional strength, damage resistance, and impact capabilities far exceed that of previously existing jar technology. An optional performance component offers operators a safeguard against pulling the jar beyond its mechanical and hydraulic limits which can render it useless down hole. In addition to safeguarding the tool from damage, this module also allows the tool to be pulled to its maximum rating, every time, insuring the hardest possible impact every pull. This paper will detail how the use of this innovative tool has provided flawless performance in the North Sea and offers a true step change in jar technology to the drilling industry. Case studies and field data provided will support and demonstrate increased performance unmatched in the industry today.
Mitigating down time, while curing losses, is a critical part of designing and executing a good well plan. Even when anticipated, the loss of drilling fluids to depleted formations is a costly event resulting in excessive down time for the entire rig as well additional costs in replacing costly drilling fluids.The search for new hydrocarbon reserves increasingly sends us back to proven fields where drilling through depleted zones as become an increasing liability to daily operations. The costly time required to pump multiple activation and deactivation balls down the string makes operating conventional tools tedious and time consuming. A more efficient tool for the placement of lost circulation materials (LCM) that does not require the exorbitant lost time and complicated cycling methods of the current technology has not been available for over a decade.Today, a new tool, utilizing innovative shifting technology, provides unlimited open / close cycles. With this technology, drillers can shift an unlimited number of times and in as little as 5% of the time required by conventional tools. These capabilities result in direct reduction of lost time operating the tool as well as a quantifiable reduction in fluids lost while operating the tool. Simplified operation also makes the tool uniquely easy to operate reducing the potential for user errors that frequently plague existing technology. This paper details how the use of this innovative circulating technology has assisted a major service company in reducing downtime and excessive costs during lost circulation events. The design has proven simpler to operate and has effectively reduced the non-productive time and lost fluid versus operation of conventional circulating subs. Supporting case studies are included to detail the increase in efficiency and reduction in costs.
Jar technology has been around in the oil industry for several decades and its basic principles have remained primarily the same. As the oil industry moves forward in the exploration and development of unconventional hydrocarbon reserves, the demand for tougher, more reliable, and safer tools is more critical. Deeper wells and more complex well geometries are pushing the drilling envelopes, requiring tools to be engineered not only to withstand higher stresses downhole, but also to provide higher levels of safety on the rig floor. Through the engineering of simple but ingenious features, this paper describes how jar technology has been taken to a higher level. A jar has been designed acknowledging the most important features required in the current demanding drilling scenarios. The industry is not only looking for safer and more reliable tools, but also tools that will provide higher firing loads to increase the levels of success of freeing a drill string during a stuck pipe incident. The loads delivered during the first hours of a stuck pipe event can significantly improve the chances of retrieving the drill string safely to surface. The design features employed in this new technology maintain the same operating procedures of standard designs, but have increased the torque, tensile, and pressure ratings of the tool. In addition, current technology can suffer damage from excessive internal pressure build up when the over-pull rating of the tools are exceeded; particularly in deepwater applications where heave can be a contributing factor. A device has been engineered to protect the tool if such a condition is reached. The new jar also features a modular safety mechanism that will eradicate the use of the traditional safety collars eliminating the potential hazards of dropping objects on the rig floor. This paper will provide an overview of the innovative technology, plus review the initial field trials. Testing and field trials will demonstrate how this technology is a true step change, matching the growing demands of the drilling industry.
Previously, few options existed for the complex directional challenges. Drillers either needed to rely on multiple Bottom Hole Assemblies (BHAs) or use expensive drive systems, which resulted in increased operational cost and limited drilling flexibility. This novel Downhole Adjustable Motor (hereafter referred to as downhole adjustable motor or the motor) described in the paper addresses these limitations by enabling the driller to change the motor bend in real-time downhole. In addition, the motor can deliver up to 1,000 horsepower (HP) at the bit during rotary drilling—the highest power in its size range. This paper will review how, even in harsh drilling applications, the downhole adjustable motor has proven to save trips, increase bit life, reduce lateral vibrations and stick-slip, and allow for drilling optimization to increase Rate of Penetration (ROP) and decrease overall drill time. Whether for drilling contracts or lump-sum turnkey projects, the directional drilling industry benefits from this new technology's ability to improve drilling economics while increasing safety by reducing drillpipe tripping and additional BHA handling.
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