The challenging environment in the Kvitebjørn field offshore Norway comprises high-temperature wells, long drilling hours, low rate of penetration (ROP), managed pressure drilling (MPD), and mud additive requirements, all of which are very detrimental for operations and reliability of the positive displacement motor (PDM) power section. In fact, until now, no one has successfully drilled the 5 ¾-in. section in a single run due primarily to motor failures such as elastomer chunking and debonding. This paper presents the steps used for optimizing the selection of a PDM section to achieve a single-run drilling operation with improved ROP. The method includes understanding the drilling environment, type of wells, rig capabilities, formations, temperatures, MPD, and drilling fluid requirements. Furthermore, the usual motor and bottomhole assembly requirements must be evaluated and the mud compatibility with the elastomer must be scrutinized. All of these variables were then input into a modeling engineering workflow to simulate and analyze the power output, the elastomer fatigue life, the hysteresis heating, and the debonding stress to select the best possible PDM candidate for the drilling job. A new long-life elastomer and the drilling parameters recommended by the mud motor modeling resulted in drilling this section in a single run for the first time in the field. Simultaneously, it was possible to drill to the deepest total depth without any need to set the section total depth shallower, as occurred in previous wells due to motor failures. The motor drilled through a very thick cemented sandstone stringer with no stall incidents. This motor set new records for drilling the 5 ¾-in. section with a total run length 60% longer than the previous longest run and a total pumping time 67% greater than the previous record. The combined new technologies of the modeling and the new long-life elastomer were applied for the first time in the anticipated challenging drilling conditions. The successful results demonstrated that with thorough analysis and proper planning, one can achieve a step change in performance and reliability without additional costs. The scope of the operation is even broader than the mud motor application.

Today, drill bits and mud motor issues often account for more than half of the reasons for pulling out of hole before total depth (TD) on typical directional drilling wells. In this paper, we present a comprehensive methodology designed for optimally matching drill bits, mud motors, and bottomhole assembly (BHA) components for reduced failure risks and improved drilling performance. The methodology consists of combining the design characteristics of drill bits, mud motors, and the rest of the BHA. Each crucial component, like the drill bit, the mud motor, or the rotary steerable system, is analyzed with a particular simulation software made for the component itself before combining the components into a system analysis tool that considers all the detailed features. For example, the simulation software for the mud motor and power section optimizes for the type of elastomer, the mud compatibility, and the fit used. Cutter types and geometries, hydraulics, rocks, and the back and side rake angles are all included in the drill bit simulation. A full drillstring and wellbore simulation takes care of the rest of the components and the link to the top drive. The workflow smartly combines physics-based simulation and data analytics to achieve the necessary level of accuracy with reasonable computation time. The new methodology presented here enables performing joint simulations of performance, durability, and stability for the first time. The performance simulation involved rate of penetration (ROP) prediction, motor power output, and available downhole torque. The durability consists of estimating the motor fatigue life, the bit wear over time, and the fatigue estimation of BHA components. The stability simulation analysis risks of lateral vibration, axial vibration, stick/slip, and bit and BHA whirl. All these are done on a system level with interdependences between different components considered. It enables matching the best bit with the best motor under the best possible BHA. The full workflow was evaluated with the drilling of a typical section in the Permian with significant improvement in both the ROP and reliability. In summary, this paper describes a collective simulation capability that enables matching the bit, motor, and BHA by evaluating the design characteristics of each component and combining them into a system-level simulation tool. It enables joint evaluation of the ROP capability, bit wear, motor fatigue life, and BHA shock and vibration. At the end, we can perform fast drilling without compromising durability or reliability.

The deployment of a new positive displacement motor (PDM) technology as a solution to improve drilling performance in deep vertical exploration wells in northern Kuwait. The new technology of the positive displacement motor was developed within the framework of new capabilities in motor optimization modeling, a holistic approach to configuring motor components as an integrated unit, and new engineering advances in the material and design of motor components. The engineering advances and innovations can be distinctly categorized into two major components, the power section and the lower end. The power section components went under extensive empirical and experience-based failure analysis to refine the design of the subcomponents. The refined designs were then scrutinized with the industry-first motor optimization modeling that simulates both the performance and fatigue of the power section by analyzing eight influential variables of down-hole conditions, and components material and geometry. The second component, is the newly designed high torque lower end which houses an overhauled assembly of transmission and bearing sections. The new lower end was engineered to reliably handle and fully harness the full capabilities of the power section. The result, is an integrated new motor technology that is characterized by its superior resistance to stall, ability to sustain higher limits of differential pressure, and performance reliability in harsh drilling environment. Kuwait Oil Company (KOC), with its ever-expanding exploratory drilling campaign in northern Kuwait, was looking for significant improvements in drilling performance of vertical deep-drilling exploration wells. As such, KOC agreed to test the new motor technology in an exploration field north of Kuwait. The deployment of the new technology would take place in the 16 in section of a vertical well with a starting planned depth of 10,565 ft (3,220 m) and a total depth of 14,605 ft (4,456 m). The section drills through highly-interbedded and abrasive sandstone and carbonates strata with highly-variable windows of pore pressure and rock compressive strength. Given the complex lithology and the high-pressure environment, previous drilling campaign were tainted by low penetration rates, and motors and bits failures. In March of 2017, the new motor technology was field tested for the first time worldwide in northern Kuwait. The field test run covered an interval of 3,658 ft (1,115 m) over three runs. The new motor technology justified its higher specifications by improving the rate of penetration (ROP) by 62% compared with the fastest offset well drilled. The superior rate of penetration can be attributed to the new motor ability to deliver higher ranges of differential pressure, specifically 57% higher than offset wells. The deployment of the new motor technology successfully proved the capabilities of the new motor in drilling optimization and reliability, and also validated the engineering and modeling processes behind the new components.