Special Focus: HEALTH, SAFETY, ENVIRONMENT

Cleaning up the desert in Kuwait

 The worldwide problem of waste oil from tank bottoms and other sources, stored in earthen pits, is being tackled in Kuwait. The scale of the problem-millions of barrels-in one the world’s largest oil fields, together with the variable content of the sludge, makes for a challenging task. 

Perry A. Fischer, Editor

At a press conference, a stranger struck up a conversation about culture. “Insha’Allah,” the businessman told me, literally means “‘God willing.’ When I was in Lebanon, it meant, in a business sense, ‘hopefully.’ Here in Kuwait, it means ‘maybe, maybe not.’”

“Doesn’t that mean the same thing?” I asked.

He replied, “It’s a subtle difference.”

It’s hard to get a handle on the global volume of oilfield waste. Oil production figures are difficult enough to obtain, but reliable volumes of oilfield waste (i.e., sludge) are even more difficult. I would estimate that at a minimum, at least 100 million barrels of this waste product are generated globally each year, although the real number is probably much higher. Of this, at least 30 million barrels are tank bottoms, which is a loosely defined mixture of hydrogen-poor oil, brine and various solids. Much of this waste is disposed of in earthen pits, where the chemical soup becomes even “deader” and more emulsified.

In the US, the largest of these pits may contain as much as a million barrels of oil. In the Middle East, some of the pits contain tens of millions of barrels. Today’s combination of high oil prices and increasing pressure for better environmental practices has led to an effort in many countries to remediate these pits and, in the process, recover the hydrocarbon liquid for processing. However, the technology to do this is still evolving. While invention of a new class of technology is not necessary, the non-uniform nature of this sludge from pit to pit, together with the fact that composition often changes with depth within a pit, makes remediation a challenge.

Of the various technologies tried, some form of centrifuge for the liquid portion, followed by some form of thermal desorption for the solids, followed by some form of microbial remediation (provided the local environment permits microbial activity) seems to be the best approach so far.

This article is the result of a recent trip to Kuwait, where these pits are ubiquitous and large-the result of decades of poor production practices. However, in many ways, it just as easily could have been in Texas. In both cases, the remediation of these pits is not just technical, but also a function of governmental policy and resolve.

Lewis & Lambert is working on a contract for the removal and partial upgrading of the sludge to standards that will allow it to be processed at a refinery, Fig. 1. The contract is being carried out in the onshore Burgan Field, which is located in the desert of southeastern Kuwait and is one of the world’s largest oil fields.

Fig. 1. Sludge pits associated with Gathering Center 17 (also seen on the cover). The largest pit contains about 1.3 million barrels of oily sludge.

BACKGROUND

The headline-grabber is always about the first Gulf War, also known in Kuwait as The War of Aggression, and about how the Iraqi army blew up over 700 oil wells, of which 604 caught fire. The wells that did not ignite formed 50 oil lakes over a 100-sq-km area. Only a small portion of that catastrophe pertains to this story. By 1996, two built-for-purpose Field Treatment Centers (FTC 1 and 2), as well as existing processing facilities, had recovered about 22.5 million oil barrels from the estimated 23.5 million barrels in the lakes. A small, but unknown, amount of the worst of that recovered oil was dumped in existing oil pits that held tank bottoms and other off-spec oil.

The gushing wells permeated soil to as much as 2 m, with 80 million cu m of oiled sand. An additional 50 sq km were coated with particles of oil mist, soot and toxins, forming a “tarcrete” crust up to 5 cm deep. The production pits and remnants of the lakes continue to pollute Kuwait’s fresh groundwater supplies even today.

In late 2004, the United Nations approved payment of $2.28 billion to Kuwait to clean up pollution from the 1991 war. To date, most of this money has not been spent.

In an interview with World Oil, Dr. Adel Asem, Deputy Chairman and Director General of PAAC, the assessment of compensation authority for the UN, discussed how and when the money would be spent. Dr. Asem said that they were waiting until the cleanup criteria (specifications) had been decided on before the UN could move forward with cleanup contracts. Asked when the criteria would be settled, he was not sure. Since it’s been 16 years since the war, it’s safe to say that things are moving slowly. The money is apparently sitting in a UN account somewhere, awaiting decisions. It is also unclear whether, and how much of, the money could be spent remediating the existing production pits.

In an interview with Kuwait Oil Company’s Manager of Research and Technology, Dr. Adel Al-Abbasi (Fig. 2), Mr. Abbasi said that, in all likelihood, soil remediation will require some form of thermal desorption. Various studies and pilots occurred under the Kuwait Institute for Scientific Research (KISR) and at the University of Kuwait. I visited the site of one of these pilots. A report said that the remediation of the sludge was successful, although not in the sense of a contractual specification. Soil remediation, using High Temperature Thermal Desorption (HTTD)-not to be confused with incineration-seemed to reduce the oil content to a minimum.

Fig. 2. The intrepid Editor interviewing the manager of Kuwait Oil Company’s Research and Technology, Dr. Adel Al-Abbasi. On the right is Musab Ahmed Bazie Al-Yaseen, agent for Lewis & Lambert and head of his own Kuwaiti firm, Geotech Environmental Services.

From what I could see, the pilot partially succeeded, but bioremediation would require a large amount of soil amendments (mulch), and continuous watering before microbial activity could turn this black, roadbed-like material into soil, which would be very expensive in a desert where temperatures can exceed 50°C (122°F). Visually, it still looked a lot like tarcrete, Fig. 3.

Fig. 3. The results of a soil remediating project. While an improvement, the result feels more like road building material than soil. A similar looking material-tarcrete—covers over 50 sq km.

PROCESS OVERVIEW

Lewis & Lambert is involved in the separation of sediment, water and associated contaminants from oilfield sludge in Kuwait in Burgan Field, the sixth-largest oil field in the world on an original-oil-in-place basis. A three-year, renewable contract calls for the processing of 1.3 million barrels of sludge for input into the refinery/upgrading system. There exist numerous other pits in Burgan, some of which contain more than 10 million barrels of sludge.

The first step is removing and processing the sludge in the pits (Fig. 4): The process uses a three-phase centrifuge as a mechanical means of separating oil, water and solids. Applying heat is very helpful to the process and serves to reduce viscosity and help chemical additives to mix into the sludge.

Fig. 4. Schematic of sludge and processing in the field near Gathering Center 17.

Here are the details:

1. A long-reach excavator and/or a progressing cavity pump or similar is used to move the sludge from the pit and into a steam-heated (70°-80°C) hopper tank. This reduces the viscosity so that debris can be filtered off and the sludge can be pumped into blending tanks for processing.

2. While in the blending tanks (Fig. 5), the sludge is injected with kerosene and/or diesel and other thinners/chemicals via a chemical pump to help induce separation of oil, water and solids.

Fig. 5. One of three heating/mixing tanks. These are just upstream of the final heating/chemical injection and centrifuge separation.

3. From the blending tanks, the heated sludge is pumped through a heat exchanger, which further heats the sludge to the optimal process temperature, 100°C, where the gravities of the chemical-treated oil, water and solids have the highest potential differential.

4. While in the heat exchanger, a final chemical injection is applied.

5. The sludge is then passed to the centrifuge, where the sludge particles are separated by the centrifuge’s G-force.

6. The recovered oil is pumped to a collection tank via an oil weir; the produced water is pumped to a collection tank, and the produced solids are pumped into a collection container and removed, in compliance with Kuwaiti Environment Public Authority (EPA) regulations.

7. The recovered water is pumped via a flowline to a storage tank. From there it either goes to an evaporation pit or to a disposal well.

8. Recovered oil, once tested and accepted, is pumped (or can be trucked) to the Gathering Center for processing for sale.

In general, the three-phase process can reduce BS&W to 0.5-1.5%, from 50-80%, while water content in oil can go from watery sludge to a processed level of 11 ppm or less, according to tests done at Los Alamos National Lab in the US. It is anticipated that, with every few inches that the depth of a pit decreases, the chemistry of the process will need to be altered.

Since Kuwait has very salty oil and water, this will be reflected in the pits, so desalters will be needed. Also, since the water content and emulsion characteristics will vary, the chemistry must also change to keep the sale oil on spec. Software that aids in this process has been specially created for that purpose in a US Department of Energy-sponsored project at Los Alamos National Laboratory.

When the soil stage is reached, a particular technology will have to be settled on, and contract terms determined.

GOING FORWARD

As already alluded to, there are parallels between the US and Kuwait. In addition to the problem of sludge pits, both countries have conflicted environmental agencies. In the US, the former head of the Environmental Protection Agency, Christine Todd Whitman, was unknowingly hired, in the words of one political pundit, “to keep the woods safe for steeplechase, and nothing more.” But she soon found herself in charge of a highly technical group of scientists, all of whom wanted to do their jobs, and, as it turned out, so did she. The law made it clear that this was exactly what she was supposed to do; that is, her job description was specified by law, which conflicted with political pressures to do little or nothing. Eventually, she resigned.

The situation is remarkably similar to Kuwait, whose Emir-National Assembly created the Kuwaiti EPA in 1995 -1996, and charged it with broad responsibility to protect the environment. It’s been as political as the US EPA. Should Captain Ali A. Haider, the newly appointed Acting Director General of the Kuwaiti EPA, decide to stay, he will face a number of challenges, and some of them will be in the desert.

For example, the practice of dumping off-spec oil (sludge) in pits has not completely stopped, as I saw vacuum trucks dumping into a nearby pit. Flaring has been reduced, but the practice continues, despite EPA efforts. Evaporation pits are still common, and brine scars are every bit as troublesome as oil sludge.

As with most of the Gulf Coast region, a massive construction boom is underway. While eating lunch in a high-up restaurant, I counted over 40 tower cranes. Those buildings will all need electricity, and demand for electricity will more than double within a decade or so across the region if current rates continue. Kuwait now burns over 70 million barrels a year of oil for electricity generation, most of it heavy with moderate sulfur content. You can tell there’s sulfur dioxide in the air, and that it will only get worse.

There are pilots, preliminary and FEED studies for moving forward in energy production in a more environmentally benign manner. In the past, KOC did not have to worry about water production. Like most of its neighbors, if water became a problem, they just shut the well in. Now, watercut is up to 25%. In less than 15 years, it will exceed oil production. Fortunately, like in the US, where 10 barrels of water are produced for every barrel of oil, it is mostly being re-injected, either for pressure maintenance or for disposal.

Kuwait is already one of the leaders in desalination of seawater. Experimental technology from a Japanese company can take highly saline water-say, 160,000 ppm-and reduce it to 10,000 ppm. The technology is being considered for niche applications to deal with the ever-increasing need for water in industry.

Gasification of heavy oil is being studied. Not only would it solve the sulfur problem, but it would also provide a market for the billions of barrels of heavy oil that Kuwait has, and provide the region with an example of how to use the resource. KOC recently discovered a major gas field with reserves possibly in excess of 10 Tcf, but it has yet to be delineated. Importation of CNG or LNG from neighboring gas-rich countries is also an option being considered to increase electrical production without polluting the air.

Miles of desert are being planted and irrigated to create windbreaks and beauty. Kuwait is clearly on the right path. But the pits, well, that’s easy-they’ve got to go, insha’Allah.  

ACKNOWLEDGEMENTS

Special thanks go to Ken Havard for being a great companion on a short, hard trip and for supplying background on the various people involved; Dr. Adel Al-Abbasi, an extremely knowledgeable man who generously gave time to a complete stranger and explained things slowly; Musab Ahmed Bazie Al-Yaseen, a former SPE Chapter President for Kuwait who seems to know everyone, who opened doors on short notice and provided transport in the Kuwait City heat; Captain Ali A. Haider, Acting Director General of the Kuwaiti EPA; Mazen D. Al-Sardi, Managing Director, Oil Services, Kuwait Oil Co.; Ali Hussain Al-Kandari, Team Leader Production Operations, Kuwait Oil Co.; Farouk H. Al-Zanki, Chairman and Managing Director, Kuwait Oil Co.; Martyn Canavan, for providing background information; Heuy Lambert and Laura Lewis, my benefactors and organizers on the trip; and Jim Lea, for offering me up for the trip.