A couple of recent events highlighted the ability of oil and gas operations to multiply the good in good projects and the potential for those operations to trigger disastrous consequences.

The good side of that equation earned the Norwegian Petroleum Directorate (NPD) improved oil recovery (IOR) prize for 2006. The bad side — although there is no proof that drilling operations were responsible — is the Lusi mud volcano in Indonesia that left nearly 4 sq miles (10 sq km) of land uninhabitable and put 11,000 people out of their homes.

On the good side, Baker Hughes and Halliburton jointly earned the IOR award for combined technology in horizontal and multilateral wells used to develop Troll field offshore Norway.
Troll might not have been a commercial success using standard vertical wells because of its thick oil intervals. Norsk Hydro tested two long horizontal wells, one in an 88-ft (27-m) oil column and another in a 43-ft (13-m) oil column. The field now has more than 150 horizontal wells, some with up to seven laterals. The field went from potentially no reserves in 1986 to 1.5 billion boe, and horizontal wells made it Norway’s biggest producer for some time.

Hydro earned an IOR award in 1998 for that effort, but it had help from Baker Hughes and Halliburton working together. According to the NPD, “These developments on Troll would not have been possible without the good cooperation between Baker Hughes and Halliburton, who are competitors, to get all the pieces to fit together, both during the planning of wells and in the operational phase.”

Specifically, the teams used Baker Hughes INTEQ Navigator and AutoTrak to precisely place the horizontal shafts close to the oil-water contact, but not so close that they would allow water coning. INTEQ also designed fit-for-purpose bits for the field.

Baker Oil Tools provided the Equalized Inflow Control Device, based on a Hydro patent, and provided choking that allows even inflow of oil along the long horizontal well bores, again to avoid coning. The company’s gas lift technology allows use of gas from the field’s gas cap to increase oil production.

Halliburton provided the FlexRite and ReFlexRite systems that made the horizontal wells efficient multilateral wells. Those systems streamlined the installation of junctions in the horizontal wells that made them into multilateral wells, starting with the first isolated tied-back system in the world in a Troll well in 2001. The systems allowed construction of multilateral wells in shorter rig times with lower costs than previous systems.
Troll now has 43 mulitlateral wells.

Hydro also is using the horizontal and multilateral wells at other locations, notably its Grane field, and it plans to use the technology on other installations in the Norwegian offshore and in its expanding operations offshore Brazil.

Cooperation among the companies multiplied the beneficial effects of lone technologies from any single company in the partnership.

On the other side of the coin of potential consequences, the Lusi mud volcano blew out last year, flowing between 247,000 and 5.3 million cu ft (7,000 and 150,000 cu m) of mud a day for months and possibly years.

To date, the volcano in the Porong subdistrict of Sidarjo, East Java, has destroyed four villages and 25 factories, and 13 people died when a gas pipeline ruptured beneath a holding dam built to stabilize the mud flow.

According to a team led by Durham University in the United Kingdom and published in the US journal of GSA Today, the eruption probably was caused by an exploratory well near the volcano.

Mud seeps and water seeps are common in many places in the world, but eruptions usually are preventable when operators drill for oil or gas, the Geological Society of America article added. “It is standard industry procedure that this kind of drilling requires the use of steel casing to support the borehole to protect against the pressure of fluids such as water, oil or gas. In the case of Lusi, a pressured limestone rock containing water was drilled while the lower part of the borehole was exposed and not protected by casing. As a result, rocks fractured and a mix of mud and water worked its way to the surface. Our research brings us to the conclusion that the incident was most probably the result of drilling,” said Prof. Richard Davies of the university’s Centre for Research into Earth Energy Systems.

A similar event occurred in the Pacific Rim in 1979 and required 30 years, 20 relief wells and constant monitoring before the eruption stopped, he said in a statement released by the university.

Opposing the university findings, some people have said that an earthquake in the area 2 days before the eruption could have caused the event, but a team from Durham, Cardiff and Aberdeen universities and GeoPressure Technology Ltd. say that’s not likely.

The time between the earthquake and the mud eruption was one deciding factor, they said, another was the fact that no other mud volcanoes in the area erupted, and a third was comparison with similar geological events.

Whether that well actually triggered the mud volcano’s eruption or not, the potential of oil and gas drilling operations to create disasters of this magnitude is frightening.

Let’s aim for the Norwegian example and avoid the Java consequence.

Comments