Zara Khatib - an oil and gas expert - who is an energetic female in a man's world

Zara Khatib, Shell's chief technologist in the UAE, now hopes to turn her expertise in oil and gas extraction to purifying the saltwater underneath the desert sands.

Zara Khatib, Shell's technology manager in the UAE.

Men come knocking on her door. They want her time, her help and her approval. They murmur in Arabic: "Afwan, doctora", apologising for interrupting her work.

The woman they seek is armed with a BlackBerry crammed with photographs of baby birds and sits in an office cluttered with personal artefacts - a folding hairbrush here, a vine inching out of a used Masafi water bottle there.

The doctor is Zara Khatib, Shell's technology manager in the UAE and an expert on technical matters in the oil and gas industry.

For nearly three decades she has invented methods for one of the world's biggest energy companies to extract more crude from the ground. Years solving problems in oilfields from Alaska to Nigeria have won her prominence in the energy sector, still one of the hardest for women to break into.

Now she harbours a different dream; to purify the saltwater that lies under the desert sands.

By harnessing the sun's energy, she hopes to bring freshwater to people's backyards, fulfilling a critical need as climate change and population growth threaten the balance of the world's resources.

To be successful, Dr Khatib will have to find a corporate partner, secure a patent from Shell and overcome scepticism about an idea that has been dubbed "greening the desert." But she is used to remarkable odds.

"It's not easy, because oil and gas [are] still a bit of a man's world," says Pieter Kapteijn, who worked with Dr Khatib at Shell in the late 1990s. "Only if the company actually makes it a policy to pull the women through the ranks and spends more time thinking about how to pull them through the ranks do you see a difference."

Dr Khatib did not advance by keeping quiet. In November, she listened to a speech by the UAE's Opec governor at the Petroleum Institute, where she spends four out of five days a week helping to launch an academic centre dedicated to natural gas. She had a question for Ali al Yabhouni. Did he, she asked, think there could eventually be such a thing as the Organisation of the Gas Exporting Countries?

Asking provocative questions is Dr Khatib's style, said Mr Kapteijn, who is now the director of technology and innovation for Maersk Oil.

"She's opinionated, she's really assertive," he said. "I'm a little biased. We Dutch love that sort of stuff."

Dr Khatib's rise from a top technology office at Shell began in the war-torn neighbourhoods of Beirut. With a father trained in engineering who sold fruit and vegetables and a mother who married at the age of 13 because she was an orphan, Dr Khatib, who is now 56, had a serious childhood. At the age of 11, taken with the idea of studying engineering in London, she stopped wearing sweaters on all but the coldest days to begin an early climate adjustment.

In 1975, with conflict breaking out in Lebanon, she left for the UK to pursue advanced degrees in engineering, pushed by her parents' wish that she live far from danger.

In London she began to see the link between the environment and the energy industry that she aspired to join. A classmate had invited her to smoke a cigarette, a first for the 21-year-old who had never even touched a shisha. Just after she lit up, Dr Khatib's department head appeared.

"He came in and saw me, you know, puffing. That was my first cigarette and my last one," she said. "He said 'shame on you. You're supposed to clean up the environment, not pollute it.' And that was it."

That environmental awakening was the beginning of a career that combined the business of extracting fossil fuels from the ground and conserving the world's resources. One of the common problems in the oil and gas industry is that large amounts of water are pumped up along with the fuel, more so as fields age. In Oman, for example, every barrel of oil was accompanied by eight barrels of water.

Once recruited from academia to Shell in Houston, Dr Khatib carved out a speciality managing that water flow and finding ways to extract more oil out of the ground to increase the lifespan of a field.

"People think if you work for an oil industry, which is a polluter, or a chemical industry as a polluter, it's wrong," she said. "But if you think about it, people want the energy. So if they want the energy, give them the most appropriate energy."

Working as an oil and gas engineer in the 1980s required Dr Khatib to venture to places where no woman before had set foot. While conducting research for a post-doctoral degree in the UK, Dr. Khatib and a colleague visited a British refinery to collect an oil sample. Her male colleague went in, but she was stopped and told that no women were allowed on site, Dr Khatib recalled. "I said, 'OK, where is that coming from? I'm an engineer. We have permission'."

Told to wait for her colleague, she was escorted to a porter's room plastered with photos of naked women.

"It was so humiliating, sitting in there," she said.

There were similar incidents once she joined Shell. Dr Khatib recalled workers answering her questions by addressing her male colleague.

"Men didn't know how to react and behave with women around them, because neither their mother or sister or wife worked," she said. "So they've never been in a working environment with women with them. When I used to go offshore, the first day not only the fact that I am so knowledgeable but that I am a woman - … they were scared. The second day they start realising I'm competent, I know what I'm talking about, I'm trying to help them. The third day they work with you."

Such experiences have earned her the privilege of flying around the world to represent Shell, at one point sitting alongside the UN secretary general Ban Ki-moon to speak about the status of women in the workplace.

While Dr Khatib was working with Shell in Houston, a friend told her she should meet another employee at the company, a Texan man who had converted to Islam a decade earlier and who happened to know Dr Khatib's father.

"No," Dr Khatib remembered telling her friend. "Why don't you go and introduce yourself to him? I'm not going to marry, I'm busy offshore, going everywhere."

But she did agree to lunch. The following day, the man, now a senior adviser at an Abu Dhabi Marine Operating Company, asked her and her parents to dinner. Dr Khatib, then 30, was nine years younger and still working her way up the payscale - but she had met her future husband. She recalls him saying: "There will be a time when you're going to make more money than I am, and that doesn't bother me." And she recalls her response, too. "He's the man I want to marry."

Dr Khatib these days splits her time between being on the road - a third of last year was spent outside the country - her house in Khalifa City and a spacious office at the Petroleum Institute where she keeps two computer monitors, one for the university and one for Shell.

Most days begin at 4.30 am. When she can she likes to go in her garden to marvel at the nests of baby birds.

"I like to walk in the morning, talk to birds, talk to the trees - talk to them." she said, sounding breathless. "Don't you see, it's a miracle! From a seed you have a tree."

She hopes that one day her avocado plants will thrive on water drawn from under the sand. A technology she developed at Shell uses solar power to pump water from beneath the desert to the surface, where a membrane will filter the water. The remaining mixture of salt and water will then be pumped deep underground.

She wants to spend more time on this project next year as her work with the Petroleum Institute eases.

Meanwhile another man needs her help. Her mobile plays the tune of Beethoven's Fur Elise. "This guy's calling me big time," she says, bringing her BlackBerry to her ear.