CONVENTION TRAINING: OIL RECOVERY THROUGH WATERFLOODING
By Nataša Kubíková Amanda Figueras, Salma Essam
The training session provided participants with an opportunity to acquire extensive knowledge about the most recent technologies in the area of secondary and tertiary recovery methods.
The training consisted of three major blocks. In the first, Hassan Salem, EGPC, presented an overview of waterflooding impact on the oil sector in Egypt, and Dr. Ahmed El-Banbi, Cairo University, provided an in-depth analysis of waterflooding fundamentals. The second sitting discussed four major case studies conducted by the Egyptian companies – GUPCO, Petrobel, Khalda, and Qarun. The final round of presentations focused on IOR and EOR technologies as implemented by international oil companies (IOCs) – Apache, Baker Hughes, Halliburton, and Schlumberger.
Enhancing Recovery Factor
In his opening study, Hassan Salem, Reservoir Studies Assistant General Manager at the Egyptian General Petroleum Corporation (EGPC) said that Egypt has seen a 40% decrease in oil production since 1996; the year recorded production levels of 920,000b/d. Production decline is one of the major challenges that the oil sector is determined to overcome.
According to the statistics, there are almost 90 fields with decreasing outputs. Egypt has been searching for solutions, aiming at increasing oil production from massive reserves and exploiting country’s natural resources. If this goal is accomplished, Egypt will succeed in eliminating dependence on energy imports, and in achieving energy self-sustainability, a long-term aspiration of the country.
As liquids production started declining sharply in 2015, the Egyptian oil sector has been expanding primary recovery mechanisms with secondary methods – waterflooding and pressure maintenance, and tertiary recovery schemes – enhanced oil recovery (EOR) such as thermal, gas injection, chemical, and more advanced technologies.
Studies show that, “globally, waterflooding processes, or Water Injection (WI) intensified by 5-10% resulted in cumulative oil production levels that represent 40% of recovered original oil in place,” explained Salem. The output grew further thanks to the low-salinity effect of oil enhanced recovery. In the case of GPC’s Asran field, production rates upped from 600bl/d to 7,000bl/d over steam injection technique, which was implemented as of 2002, noted EGPC Assistant GM.
In light of these enhancements, Egypt embarked upon a road to introduce new projects that would further contribute to efficient exploitation of country’s reservoirs. The existing studies and calculation strongly indicate that as of 2016/2017, the Egyptian oil sector will likely record a rise in added reserves to the production line through water flooding and EOR projects, said Salem. By 2028/2029 oil output is expected to rise by more than 1,000mbl/d, he concluded.
For future prospects, polymer injection projects are under evaluation at Petrobel, Agiba, and Petrodara. Hassan Salem also added that GUPCO is evaluating low salinity water (LoSal) injection projects. Further, CO2 immiscible flooding to be applied in Western Desert and Alkane Surfactant Polymer (ASP) flooding pilot project in Bed-1 field, are both undergoing a study phase and are being assessed for utilization.
In a two-hour detailed lecture on waterflooding fundamentals, Dr. Ahmed El-Banbi presented to the audience the key findings from main components of a typical waterflooding project to questions guiding the design of such projects to environmental impact. He also detailed additional costs incurred over waterflooding projects as opposed to primary recovery methods.
“The main goal of waterflooding is to achieve efficient oil displacement by water,” said Dr. El-Banbi. “In present, waterflooding represents the most reliable and economic oil recovery technique,” yet, as he noted further, water flood economics is problematic. “The projects involve high capital investment, much higher than primary flooding; high operating costs due to more power requirements; high risk that comes from the reservoirs themselves; whereas in return they usually generate lower profit margin than primary recovery,” El-Banbi emphasized.
The main components of water flood projects are water source, injection water treatment, injection wells, reservoir, production wells, processing of production streams, and water disposal; each of which present a challenge on its own. In relation to water treatment plant, oil companies are to focus on a series of difficulties such as filtration, de-oxygenation, chemicals or pumping. Similarly, the reservoir brings forward critical thresholds, because waterflooding projects depend on reservoir characterization, lateral pay continuity, compartmentalization, fluid distribution and saturations, natural fractures, uneven vertical fluid distribution, or lateral fluid movement.
As he explained, “managing these components in the secondary recovery processes generates higher costs than in the case of primary oil recovery projects.” In addition to structural aspects, El-Banbi further addressed key questions to be considered for designing waterflooding projects. This depends on external configuration of the reservoir and its heterogeneity, present oil saturation, wettability, oil and water viscosity, as well as optimum timing for flood.
According to scientific analysis, El-Banbi summarized that an optimized waterflooding project maintains high reservoir pressure, displaces oil towards the producers efficiently, contacts most of the displaceable oil, minimizes water production and associated water handling costs, and inevitably minimizes the impact on environment.
In addition, given the hard economics, it is important to calculate profitability of waterflooding projects in terms of how much incremental oil can be produced based on oil, water, and gas rate profiles, with respect to environmental issues.
Introducing cases of successful application of secondary oil recovery methods, the companies – GUPCO, Petrobel, Khalda, and Qarun presented their achievements in the field.
Senior Reservoir Engineer, Noureldien Darhim M., from GUPCO highlighted company’s problem with waterflooding techniques in the case of mature Morgan field, which is the poor sweeping efficiency, especially in presence of high-perm layers. He further explained that the Thermally-Activated Particles (TAP) technique can be used for in directing water into lower-perm layers. “This technique, commercially known as ‘BrightWater’, improves both areal and vertical sweep efficiencies,” he added.
Another technique in maximizing oil recovery from a mature field is implemented by Petrobel, in its Belayim Land field. Mostafa Kortam from Petrobel introduced Low Salinity Waterflooding method, which can be deployed by wettability modification towards more water-wet condition. Based on a series of experiments that the company conducted, Mostafa Kortam concluded that “the chemical mechanism for using ‘Smart Water’ for wettability alteration to enhance oil recovery is different for carbonates and sandstones.
Analysing Khalda Petroleum Company’s (KPC) experience on water flooding, Reservoir Engineer, Fathi Abokashik, revealed that “peripheral injection pattern is preferable for relatively small fields with high permeability.” Khalda’s case also showed that “focusing all wells on the field to waterflood zone maximizes benefits from the project.” Eng. Abokashik concluded that “direct injection is one of the best solutions for remote areas.” Further, KPC’s Section Head, Magdy Said, disclosed Khepri field waterflooding experience in the Western Desert. He stated that “reservoir stimulation methods contribute to improving well’s productivity/injectivity, yet close production, injection, and pressure monitoring are very critical to ensure effectiveness of the project.”
Qarun Petroleum Company is also working to boost its output from the mature Hamra field. In a comparative study on ESP Power Injection and WON Water Injection, Senior Reservoir Engineer, Sherif Mostafa, and Production Engineer, Ahmed Nasr, concluded that the importance to integrate geological and engineering understandings is the key for the success of water injection projects. Qarun thus showed that WON developments can ensure sustainable production growth and system costs are greatly lower than ESP Surface/Powered Injection.
In the final session, Production Integrity Manager from Apache/Qarun, Mike Smith, presented water clarification (WC) theory and introduced equipment types used to minimize oil/TSS (Total Suspended Solids) in produced water (PW) for injection (water/steam), disposal, and offshore overboard disposal. According to Smith’s analysis, “more often than not, the use of both cationic and anionic WC types in combination yields the most cost effective treatment and lowest TSS. “It is really important to work with reservoir production engineers and lab personnel to help identify what chemistry is needed,” said Smith.
Moving on to the tertiary recovery method – EOR – Baker Hughes’ application of chemical EOR was the subject of another presentation introduced by Colin Cranfield, the company’s Principle Reservoir Engineer. Cranfield highlighted the importance of sweep and displacement efficiency in oil mobilization as two different ways for improving chemical oil recovery. He concluded that EOR is highly desirable as ‘easy oil’ becomes depleted. However, surfactant injection is challenging, particularly in high salinity, high temperature environment; Alkalis is cheap, but brings associated operational problems; and polymer floods can be implemented in sandstones.
Halliburton presented its polymer injection well project the involved permanent reliable monitoring for downhole conditions. Ahmed Magdy and Khaled El Ashkar, Technical Professional Associates revealed the ways in which reservoir monitoring should be managed.
In the last presentation, Schlumberger engineers presented on water flood management, reservoir monitoring and control technologies.
As Dr. El-Banbi explained, recovery efficiency for most waterflooding projects ranges from 35% to 65 % of original oil in place (OOIP). Lower values come from heterogeneous reservoirs with high contrast layers, flat and thin reservoirs, high viscosity oils, poorly designed projects, and badly managed operations.
Based on the existing analysis, he recommended improvements in two areas: development and operations. In developing waterflooding techniques, companies are to understand the reservoir well, start waterflooding early, infill drill to reduce effects of lateral pay discontinuities, develop field on pattern waterflood, open all of the pay in all wells, and finally, investigate the utilization of smart water (pilot). In the area of operations, Dr. El-Banbi recommends keeping producing wells pumped off, injecting below formation parting pressure, injecting clean water, managing waterflood by injection well tests, and conducting a surveillance program.