New Positive Displacement Motor Technology Significantly Improves the Drilling Performance through Challenging and Abrasive Strata in Northern Kuwait
Authors: Alattar A. , Mustafa M. M. , Nobre D. , Applegate R. , Pushkarev M. , Dashti S. , Saleh K. , Saffar A. Hussein , Harbi A. Al , Anas M. 
Published: November 2017

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.