An international oil and gas exploration and production company was looking to enhance oil recovery techniques. Their operations are concentrated in south-central Oman, and Blocks 9, 27, and 62 in northern Oman. An aggressive drilling and development program was implemented at one of these fields, including a major pattern steam flood project for enhanced oil recovery. To produce feed water for the steam needed as part of the project, non-potable water from multiple sources, such as water separated from oil production, is conditioned using various technologies, including some of the largest mechanical vapor compressors ever built.
The average gross daily oil production at its designated field is 123,000 bbl (~19.6 million L) of oil equivalent per day, which is over 15 times higher than the production rate in September 2005, when they first started operating in the field. Increased production necessitated expansion and put more pressure on the operator to keep the process running smoothly.
The Problem Faced
With the introduction of enhanced oil recovery (EOR) technology in Oman, cyclic steam injection (CSI) has become an effective thermal recovery process. Several driving mechanisms, including viscosity reduction, wettability alteration, and gas expansion, influence the successful recovery of heavy oil.
Steam slurry pipelines are often exposed to high internal abrasion of the pipe wall caused by the movement of water and oil residue slurry through the line. With the effective use of technology, the wastewater pumped out from the reservoir is processed through a wastewater treatment facility, which enables the water to be reused.
Internal coating of the pipelines is required to not only provide corrosion protection, but also reduce friction and improve flow efficiency when conveying corrosive water slurry, and to offer adequate corrosion protection during subsequent transportation of recovered crude oil. The lining design specification has to withstand elevated temperatures at which the steam injection is flowed through the cycle; therefore, the main contractor undertaking the maintenance and operations of the EOR process for oil recovery at the designated field was under great pressure to reduce the friction and improve flow efficiency of the recovery process.
The EOR process and the plant have been in operation since 2010 and the internal pipe coating had been carried out using a liquid epoxy coating and fusion-bonded epoxy (FBE) in the different pipeline segments. Within two years of operation, leaks were detected on two separate occasions. The main reason was found to be the variance in temperature during the steam injection process. Moreover, the friction and high internal abrasion contributed to the deterioration of the pipes.
Back to the Drawing Board
One of the alternatives that was initially considered in 2010 but decided against in favor of FBE and liquid epoxy was a modified epoxy novolac system supplied by Belzona Polymerics, Ltd.. That exact novolac system was already successfully used between 2010 and 2013 to mitigate localized damage caused by failing FBE. Moreover, due to existing approvals from various oil and gas companies specifying this manufacturer’s materials for internal lining of pipelines and tanks, the operator reopened negotiations with its Oman supplier.
Trialing the New Solution
The first step was to ensure all relevant approvals were completed. The industry is not always keen to accept novel solutions due to their familiarity with conventional options, in this case FBE and liquid epoxy. Moreover, the contracting team was in favor of FBE and coating due to increased capital expenditures (CAPEX) associated with the new system. Examples of reduced operating expenditures (OPEX) presented during several technical presentations to the consultant were the turning point. The consultant team wanted performance assurance and proposed to do a trial application in the middle of 2012 and then inspect the pipelines after the lining’s first year in service.
Inspection of the repaired pipes was carried out in June 2013 and results were described as “tremendous.” Erosion of the lining was negligible and the pipe was in great condition for operations.
Based on the outcome of this trial, the sprayable modified epoxy novolac system was approved for their expansion project and the application for a 10,000 m2 area of pipelines was initiated. The product was approved to minimize the pipelines’ internal corrosion and to protect them from elevated temperatures.
More Challenges Faced
The application for the expansion project commenced in July 2013 and was completed in July 2014. The application was performed at a designated site by a local coating company in Oman. The lining manufacturer, in turn, was instrumental in supplying the initial technical know-how. In order to maintain high standards, a team of applicators was trained at the site and a NACE-certified inspector was present to coordinate inspection.
The challenging part of the application was the blasting of the small-diameter pipelines. The painting contractor introduced the application of a 360 degree blasting nozzle for its ease of use and the ability to achieve the required profile for application. The biggest challenge the contractor faced was trying to apply the material manually to the higher diameter pipes. The spray-applied modified novolac system is not designed for manual application and uniform thickness could not be achieved. The variance in film thickness was unaccepted by the client’s inspection team and a new application method had to be adopted.
The answer to this problem came in the form of a spin spraying system. In operation, a rotating head powered by an air motor sprays paint at an evenly metered flow against the surface. The equipment is pulled through the pipe at a predetermined speed based on the paint film thickness and type of coating.
The use of the spin spray technique was beneficial for the contractor in terms of minimizing application costs and completing the job on time.
A Favorable Outcome
To date, the application of the modified epoxy novolac system in mid-2013 is performing as expected and there have not been any instances of leakage or abrasion damage to the pipe. The nondestructive testing (NDT) inspection for measuring the thickness of the pipes resulted in minimal change in the readings. The project team is reportedly pleased with the outcome.
Successful case studies like this one are music to the ears of the oil and gas professionals who seek faster adaptation of new technologies by the industry, where consecutive favorable inspections act as undeniable proof that age old problems can indeed be solved with novel solutions
Advanced Oilfield Technology Co., LLC, (AOTC), part of Al Sulaimi Group, offers services to oil and gas, power generation and distribution, marine, defense, and construction industries as well as wastewater treatment plants, desalination plants, and steel plants. Oman Industrial Coating Centre is the largest painting contractor in the Sultanate of Oman and has performed major specialized blasting and coating jobs over the last 25 years for various clients in the government and private sectors. Belzona is a pioneer of innovative polymer technology for industrial repair and maintenance procedures and offers a range of coatings and composites carefully formulated to address various issues faced by the oil and gas industry.
Source: Marina Silva, Belzona Polymerics, Ltd., belzona.com.