Abdelghani Henni reports on how French major Total is keeping the ABK field offshore Abu Dhabi up and running past its initial life span, and beyond, serving as a pilot project for other major fields in the country.
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ABK field infrastructure offshore Abu Dhabi. Photo from Total. |
Big fields get bigger, or so the saying goes. While Total’s Abu Al Bukhoosh (ABK) field offshore Abu Dhabi, in the United Arab Emirates (UAE), isn’t among the biggest in the region, it does prove the adage.
French major Total was granted a concession to develop the ABK field in 1972. At that time, the field’s life span was estimated at 15-20 years, but, after almost 40 years, the field is still producing with an overall recovery rate at around 45%, reaching 70% in places, due to technologies Total has tried and continues to try on the field.
Total ABK, a wholly-owned affiliate of Total, continues to operate the field today, with current production at around 120,000 boe/d, 10,000 bbl of which is oil, and around 110,000 boe of gas.
The field lies offshore, on the border between the UAE and Iran, where the Abu Dhabi side of the field produces oil and gas, while the Iranian side currently produces only oil. “The geographical location makes the field very important,” says Hatem Nuseibah, President Total E&P UAE and Group Representative in the UAE, due to political tensions between Iran and the UAE.
Like many other fields in the region, ABK’s reservoirs are carbonate, but also harsh environment, with high-pressure and high-temperature.
Total’s partner on the ABK field, the Abu Dhabi National Oil Co. (ADNOC), has set an ambitious plan to increase the recovery rate of its fields to 70%. Total believes this could be possible at ABK and as a result if its belief in the field, well before ADNOC’s targets, a range of technologies have been tried on the ABK field to boost production and increase recovery rates, with successful results.
“For example, if you look at the recovery rate, today in ABK, the overall recovery rate is more than 45%, and in some reservoirs are 55%, and there is one reservoir where we have achieved 70% recovery rate. Today, it produces around 10,000 b/d at 92% water cut [across the whole reservoir],” Nuseibah says.
Gas injection
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Hatem Nuseibah |
“The first solution was the tertiary gas injection,” says Maurice Lescoeur, geology and geophysics manager at Total ABK.
In fact, Total was one of the first to apply EOR technology within the UAE, Lescoeur says. “Total ABK has seen some of the first applications of EOR (enhanced oil recovery) technology within the UAE, with the first pilot for tertiary gas injection was carried out in 1992 and followed by full field application of gas injection in 1997,” Lescoeur says.
“We started tertiary gas injection in the earlier 1990s, and we did the first EOR pilot project in 1992,” Nuseibah adds.
A key success factors for tertiary gas injection program at ABK field was a comprehensive analysis of subsurface mechanisms, though some reservoirs are very complex and conditions within some reservoirs make certain technologies inappropriate to use, i.e. exhibiting extreme high temperatures and pressures.
The tertiary gas injection technique has been responsible for 28% of production from the reservoir over the past 20 years. But it hasn’t been the sole means of increasing recovery in the field.
“We were producing a large amount of water with the gas from ABK field, so we tried ways to do artificial lift,” Nuseibah says. So far, 95% of the wells at ABK field are gas lifted, with wells completed with multiple gas lift, side pocket mandrills. Both work, but it also means decisions have to be made on a daily basis regarding allocation of available gas for injection into the reservoir for enhancing recovery versus its use for gas lift.
The latest work on the field, however, has been chemical EOR. “We also did some pilot projects with chemical EOR, and we had interesting results,” Nuseibah says. “We initiated lab studies for chemical EOR in 2010, where we developed a suitable surfactant and polymers for high sulfur (240 g/l) and high temperature (83O C, 181°F),” Lescoeur adds.
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Total Management welcomed apprentices of the Total ABK Academy in Abu Dhabi. Staff photo. |
From 2011-2013, Total’s team worked on selecting which well in the reservoir they would use for a single well pilot, as well as designing the offshore injection facilities. That led to the offshore pilot. “In 2014, we started pilot execution and we continued laboratory work to improve chemicals, while in 2015 we worked on the way forward and a multi-well pilot,” Lescoeur says.
The chemical EOR pilot project in ABK field has changed the perception of this type of EOR in the UAE. Not only did the 2014 trial lead to 40% additional recovery at the pilot well, it also lead to drop of residual oil saturation from 40% to 5%. “The chemical EOR project is particularly interesting as it uses polymers and surfactants that have never been used in such hot, saline conditions within a carbonate reservoir,” Lescoeur says. “This was a complex project completed safely on time.”It is in this area Total is looking to do further work at ABK, especially with recent technical advances in the industry. The company plans to accelerate chemical EOR deployment, reduce the cost of pilots, with a focus on standardization, modularization, compactness and flexibility.
In addition to chemical EOR, the company has also investigated enzyme EOR, but found out that it is not economic. “We are also studying further methods of EOR, like sweet water, and we are studying all other different types of EOR to pilot in ABK,” Nuseibah says. “It’s not enough to have a present development plan, we should come up with additional development plans related to EOR that can include gas injection, already used in ABK, CO2 injection and chemical injection,” he says. Smart water could also be looked at, Total has said, as well as expending the tertiary gas injection technique, which has been such a king pin for the field.
These are some of the main technologies used on ABK. Total has also deployed electrical submersible pumps (ESPs) and dual ESPs, intelligent completions, multi-lateral wells, splitter wells, and dump-flood to selective completions. It also deployed ocean bottom cables to gather seismic data, 3D vertical seismic processing (VSP) and gas tracers.
Given the age of the facilities, which has led to other initiatives such as the first composite wrap on a subsea pipeline for a Total facility, field management is a daily challenge at ABK. But, it’s also proving a prime technology testing ground and improving recovery rates at ABK could have wider implications for other carbonate fields in Abu Dhabi.
“Everything that is done with ABK field, can be used as a pilot project for other major fields in Abu Dhabi,” Nuseibah says. “Therefore, ABK is a sort of a pilot field for all of Abu Dhabi reservoirs.”
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