PDO’S Khulud project: Showcase of Oman’s ambitions to harness tight gas resources

Petroleum Development Oman (PDO), the biggest producer of oil and gas in the Sultanate, says it is continuing to make headway in unlocking the gas potential of the Khulud gas field – billed as one of the deepest tight gas accumulations in the world.

Located in the Yibal-fahud area of PDO’S concession, Khulud is seen as exemplifying the Sultanate’s ambitions to harness gas resources trapped in tight-rock within reservoirs several kilometres deep underground. PDO’S ongoing efforts to tap the prodigious gas potential of Khulud were highlighted at the SPE International Hydraulic Fracturing Technology Conference & Exhibition, which opened at the Sheraton Oman Hotel on Tuesday.

Khulud’s depth and extremely tight-rock characteristics effectively make the Khazzan gas field — the centrepiece of BP’S Block 61 project — “a conventional development” by comparison, remarked Salim bin Nasser al Aufi, Under-secretary of the Ministry of Oil & Gas, in his keynote address at the event. Success in cracking Khulud, which involves the use of fracking (fraccing) operations, will be replicated in harnessing the gas potential of similar tight-gas reservoirs in the Sultanate, he noted.

Although not as mammoth as Khazzan in terms of its hydrocarbon potential, Khulud is understood to hold several trillion cubic feet (TCF) of gas in estimated resources. Hence the extensive use of hydraulic fracturing (or fracking) — a technique in which the tight rock is fractured by a pressurised liquid — to allow the trapped natural gas to escape into producing well. In remarks to journalists, Dr Ali Ghaithy (pictured), Petroleum al Engineering Director — PDO, emphasised the growing role of fracking in the majority state-owned company’s gas business. “Fracking is very important for PDO and indeed for many other companies in Oman and the wider region.

If you look at our gas business, all our reservoirs currently are very tight and we have to frack all our gas wells. This means, to make the wells economical, we have to apply fracturing technology,” Dr Al Ghaithy, who is also the Conference Chair at the SPE forum, said.

Fracking has been paramount to PDO’S gas production since the 1990s, according to the petroleum engineer. “Our gas fields in Saih Rawl, Saih Nihayda and so on, involved fractured vertical wells. Without fracking, some of our opportunities would not have been viable. Fracking is a key enabler to have made all of these gas discoveries more economical.”

Still, Khulud’s extreme depth (some 5.5km) and complexity have effectively “pushed the envelope” in the application of fracking to tap into the reservoir, the official explained. “Khulud is much deeper and tighter, and thus presents a much bigger challenge. We are working with our service providers, while also trying to optimise and improve the entire supply chain, to lower costs. It’s only when you reduce costs and produce reasonable volumes that it becomes economical for us.”

PDO is currently studying data being garnered from a number of wells that were fractured at Khulud on a trial basis. Based on the performance of these wells, PDO plans to go ahead with early production facilities before Phase 2 of its development programme gets underway.

Previous reports by PDO have indicated a strategy to bring Phase 1 into operation by 2019 with Khulud East and Khulud West delivering 2.5 million cubic metres per day of gas.

KHULUD’S DEPTH AND EXTREMELY TIGHTROCK CHARACTERISTICS EFFECTIVELY MAKE THE KHAZZAN GAS FIELD ‘A CONVENTIONAL DEVELOPMENT’