KeBond Performance Success in Corrosive Applications

Project Information

Client Name:	Confidential
Location:	Cactus Lake, Saskatchewan, Canada
Application:	Corrosion
Initial Install Date:	August 2023
Product(s):	1″ Grade ND, NS KeBond Coated Endless Rod

Client Challenge

Corrosion on rod strings used in Progressing Cavity Pump (PCP) applications can lead to premature failure when combined with cyclic loading due to bending, axial and torsional load fluctuations. The surface of the rod is initially compromised by corrosion, which creates pitting and outer surface irregularities. These defects result in stress concentrations that significantly reduce the fatigue strength of the material. When exposed to cyclic loading conditions these stress concentrations cause microcracks to form and propagate more rapidly than they would in a non-corroded material. Over time, these micro cracks grow until the rod string ultimately fails at torsional loading well under the rated limits for a given rod size and material. These conditions lead to frequent and unexpected rod string failures. Figure 1 shows the crack propagation from a 0.025in (0.635mm) defect causing a stress concentration under cyclic bending loads.

Client GoalS

In the Cactus Lake field located in Saskatchewan, Canada, our client was faced with frequent rod failures due to corrosion-initiated fatigue. The financial implications associated with corrosion inhibition, rod string repairs, and productivity downtime challenged the economics of many wells, negatively affecting macroeconomic production targets due to increased downtime and servicing frequency.

Corrosion will affect all metal components employed in the wellbore, this includes the casing, tubing, PCP and associated accessories. The rod string is especially susceptible to fractures and failures due to the dynamic nature of what it is asked to do. Larger pumps, higher torque (and torque fluctuations), directional wellbores and advancements in drilling and production practices lead to improved oil recovery but have adverse affects on rod string performance and longevity. A solution was needed to prevent corrosion in applications where the rod string is subjected to high stress and loading conditions.

Eight (8) historical rod failures were collected and analyzed over a period of two years all concluding that corrosion was the underlying cause of poor rod string performance. A collection of figures below provides visual detail on the issues faced.

In all instances the primary failure mechanism was corrosion-initiated fatigue resulting in a reduction in rod string fatigue life when subjected to cyclic loading. Recommendations from the failure analysis reporting focused on implementation of corrosion inhibitors or utilization of a Coated Endless Rod product to enhance the overall rod service life.

Chemical treatment of the wellbore fluid with corrosion inhibitors is expensive and needs to be continuously implemented and monitored to maximize effectiveness and achieve long term results. Expensive metallurgies matched with a properly implemented corrosion program are effective at easing the effects of corrosion, but it can not be eliminated completely. If not managed properly however a significant amount of capital will be wasted on chemical, and associated workover costs due to premature failure of the rod string regardless of the metallurgy deployed. An effective long-term solution was needed.

LS Solution

Barrier coatings are used throughout multiple industries as an effective method of preventing corrosion. This includes marine, infrastructure, automotive, industrial, aerospace, construction and electrical/electronics. Essentially everywhere, coatings play a critical role in preserving the functionality, safety and aesthetics of metal structures and mechanical components.

The KeBond Coated Endless rod consists of a durable, corrosion and wear resistant coating manufactured using a proprietary process where the bare metal rod is degreased, grit blasted, heated and sprayed with a bonding agent before a dual extrusion process coats the rod string with an effective tie layer that chemically bonds an extruded layer of polyketone to the metal substrate. The resulting barrier coating is an impenetrable barrier that eliminates any potential for corrosion by effectively separating the corrosive wellbore fluids from the metal rod string. There is no potential for corrosion until the coating is worn off. The wearability of the coating is excellent in both bare tubing and lined tubing. This is accomplished through a reduction in the friction between the two components. KeBond coating wear can be accelerated by rough, corroded or damaged tubing, production of abrasive depending on their aggressiveness, and increases in side loading as it relates to the wellbore trajectory.

Operational Results

Several strings of KeBond were initially deployed as field trials in the Cactus Lake field based on historical rod string performance where corrosion and fatigue were the main contributing factors in high intervention frequency.

Current KeBond results as of July 2024 for Well1 are compared to historical rod string performance in Figure 6. The base run time (BRT) based on the average intervention frequency was established at 30 days. Economic success based on the incremental cost of the KeBond was established at 120 days as the target run time (TRT). The bare rod under the KeBond coating was 1in (25.4mm) Grade
ND. The KeBond in Well1 was surfaced due to a drop in torque on April 11, 2024, after 133 days in operation. This created an opportunity to inspect this string after close to 4 months. The KeBond showed minor wear, with some wear on the bottom pin connection.

Well2 experienced similar results as illustrated in Figure 8. A 1 in (25.4mm) Grade NS KeBond string was deployed after establishing the BRT at 30 days. Many rod related interventions plagued this well over a 2 year period prior to KeBond installation in August of 2023. Economic success was similarly established with a TRT of 120 days.

COnclusion

KeBond has proven in these applications to significantly improve rod string performance and uptime through corrosion mitigation. Well1 has exceeded the BRT average of the previous interventions by close to 6.8x. The TRT was exceeded and currently sits at just over 1.1x the key performance indicator. Well2 has shown impressive performance results with the BRT exceeded by 10.1x and the TRT sitting at 1.7x the economic success threshold. Both wells are benefitting from a reduction in servicing frequency and associated costs, while seeing and improvement in production uptime driving consistent revenue.

Based on the initial success of KeBond in Cactus Lake, a total of 46 strings of KeBond have been installed as of July 2024 in similar applications with corrosion related problems. Results in the bigger subset of installations continues to show positive results. Lifting Solutions continues to focus on designing and applying KeBond strings into problem areas while monitoring strings as they are surfaced for wear and any other rod related indications as this innovative product matures as an industry solution.