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Home / Issue Archive / 2008 / September #9 / TNK-BP Offers a New Dimension on 3-D Seismic

№ 9 (September 2008)

TNK-BP Offers a New Dimension on 3-D Seismic

“In Orenburg, at another mature field we decided to go straight ahead with 3D and shot around 1,500 sq. kilometers. We paid just under $5 million for the license at auction. We shot 3D – that’s probably another $15 million to $20 million. But we have probably proven a further $150 million of value in field extensions, which are now being drilled,” says Chris Einchcomb, TNK-BP Vice President for Exploration.

By Materials supplied by TNK-BP

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“In Orenburg, at another mature field we decided to go straight ahead with 3D and shot around 1,500 sq. kilometers. We paid just under $5 million for the license at auction. We shot 3D – that’s probably another $15 million to $20 million. But we have probably proven a further $150 million of value in field extensions, which are now being drilled,” says Chris Einchcomb, TNK-BP Vice President for Exploration.
 The notion of being able to peer through solid rock looking for treasures buried deep in the earth should sound as far fetched as something from Star Trek or Super Man. Yet, such work is far from being science fiction and is performed on a daily basis in the search for hydrocarbons worldwide. Rather than using Superman’s X-Ray vision, oil companies employ seismic technology, a tool that offers oilmen a glimpse of Earth’s geology as deep as several kilometers below the surface. Images obtained through the use of this technology prove especially rich if high-quality 3D seismic is employed. This technology offers oil companies an efficient tool to develop not only greenfield projects, but successfully maintain mature oil fields. The correct and timely acquisition of 3D conducted at very mature and significantly depleted fields can make a difference big enough to become a decisive factor in continuing to operate an otherwise commercially unviable project. “It’s unlikely 3D will find another billion barrels in these older fields,” says Chris Einchcomb, TNK-BP Vice President for Exploration, adding, however, that a good quality 3D seismic study can really change the life of a mature field. More than 80 percent of Russia’s oil production today comes from mature fields, where production began as early as the 1960s and 1970s. Today TNK-BP leads Russia’s oil sector in 3D seismic acquisition. It accounts for more than 25% of the country’s seismic market.
And although costly and extremely technologically complex, 3D seismic is already yielding returns at TNK-BP’s mature production sites allowing drilling to be much more accurate and revealing undrilled satellites and closures in mature fields.
“Last year in particular and certainly this year, a lot of the Upstream businesses are seeing the value driven by examples like Kamennoye, Bakhilovsky and Orenburg where 3D can make a difference in development”, says Einchcomb.
At Bakhilovsky field, one part of a large group of oil fields in the Business Unit East region, 3D seismic acquisition has shown a number of accumulations. This resulted in an increase in daily well output from just 10 tons a day to 120 tons a day in newly drilled exploration wells.
“At scale this can transform a business,” says Einchcomb.
“Also, in Orenburg, at another mature field we decided to go straight ahead with 3D and shot around 1,500 sq.  kilometers.
We paid just under $5 million for the license at auction. We shot 3D – that’s probably another $15 million to $20 million. But we have probably proven a further $150 million of value in field extensions, which are now being drilled.”
Most of the fields in Orenburg have also been developed since the late 1960s and saw production peaks back in the 1970s.
However, after a couple of decades of steady output decline these old fields are seeing new growth. Production would have not reached current levels without the application of up-to-date technologies such as 3D seismic.
Seismic technology had been applied in the Soviet oil sector for decades. Initially it was only 2D seismic – a series of sparsely spaced profiles, used primarily as a tool for identifying potential hydrocarbon-bearing structures, which were then drilled.
3D-seismic technology was introduced in the Soviet Union in the 1980s and is not a truly new concept. According to Einchcomb, just like with any other technology the success is tightly connected to having the best quality, in this case for each of 3D acquisition, processing and interpretation.
“What has happened is an increase in the quantity of 3D acquisition and a significant increase in the use of various applications of 3D,” says Sergei Ostapenko, Director of Brownfield Exploration and Appraisal Department, pointing to the progress made in 3D application that took place since the inception of TNK-BP. “3D seismic provides a means to analyze reservoirs and do it through a variety of methods. In the old days we mainly focused on just understanding the outline of the geological structure,” says Ostapenko.
3D seismic technology was not used in the USSR across the board – a gap that TNK-BP is planning to close shortly.
TNK-BP’s strategic plan to cover all of its 15 top fields by 3D will be achieved by next winter, instead of in 2010 as initially planned. Thereafter, only Samotlor field, once the main Soviet oil production base and one of the planet’s largest oil fields would remain outstanding. Conducting 3D seismic acquisition over all of Samotlor would require covering an area of 4,000 sq. kilometers, or over 3.5 times the size of Moscow.
This is underway now. It will take another two years and be completed during 2010.
The aggressive application of 3D seismic technology is reflected in the company’s policy on investment into exploration and development.
“In the first year of the company, we probably spent in the order of $15 million on seismic. This year we will spend about $150 million. This is a ten-fold increase,” says Einchcomb.
The surge in spending is also reflected in the volume of work done. In 2003 using only five crews, TNK-BP shot about 500 sq. kilometers of 3D and 2,000 kilometers of 2D.
2007 saw TNK-BP utilizing 28 crews, which shot just over 6000 sq. kilometers of 3D and over 5,500 kilometers of 2D.
“2D programs have increased, but the real increase has been in the 3D seismic,” says Einchcomb. Broad 2D seismic is often used to provide an initial understanding of the subsurface before beginning work on obtaining a much denser and informative 3D picture.
Often, the licenses that TNK-BP acquires already have 2D seismic data, allowing the company to proceed directly to 3D seismic acquisition.
“We are now moving into the stage where we are using 3D to better focus exploration and development activity. And it has given us a much better picture of the subsurface”, says Einchcomb.
Ostapenko also notes that at TNK-BP’s oil fields located in Orenburg and on many Western Siberian projects, the company now prefers to move straight to 3D seismic acquisition.
TNK-BP is also working on further streamlining and perfecting the application of 3D seismic, as accuracy and precision directly affects overall costs and returns ratio.
“TNK-BP spends a billion dollars a year on development drilling. If your success in development drilling is 80 percent, then you are effectively wasting $200 million every year on development wells that don’t give you the kind of results that you want,” Einchcomb notes.
A lot of work is being done on collecting a database that would allow better visualization of complex subsurface structures.
Even today, there is still not enough information on the behavior of various types of geological structures in Russia’s oil-bearing provinces, like Western Siberia. So seismic in Russia is currently not used for quantitative assessment. It’s qualitative, Einchcomb says. So far experts are looking for potential oil, or hydrocarbon bearing structures. But with better understanding of the rocks’ properties, exploration and development results can become more predictive in terms of finding actual reservoirs.
“Somewhere like Western Siberia and Orenburg – our main areas – the current understanding of the rocks and fluids and the seismic response is still in its infancy,” says Einchcomb.
However, every TNK-BP field screened with 3D technology has brought not only new hydrocarbon finds, but also accumulated knowledge to help analyze data elsewhere in the future.
Some progress has already been made in Yugra, in Khanty-Mansiisk Autonomous District, where TNK-BP is developing new fields.
“There, we are using seismic attributes whether it’s amplitude response, or coherency, or seismic inversion techniques that can actually predict reservoir quality. The prediction accuracy is really good,” says Einchcomb.
Another area of streamlining lies in forging closer links between all the stages of 3D acquisition and interpretation.
For the most part, TNK-BP currently hires crews for acquisition and uses the services of WesternGeco, part of the Schlumberger group, for processing the data. Interpretation is carried out mainly by contractors but the goal according to Einchcomb, is to unite interpretation and processing quality control under one roof within the company.
“We want to improve our own in house seismic interpretation skills and drive more integration between geology, geophysics, engineering and ultimately development drilling. That’s not something you can change overnight. I think it would have to be three or five years before you could say: everything is being done efficiently in house,” says Einchcomb.
Work is also underway to look into the feasibility of generating preliminary products in the field and passing it to interpretation teams while the detailed seismic processing is conducted. Through such a link the data gathering process could then be adjusted to generate a better result, while the whole process, which currently takes about 24 months from start to finish, could be accelerated. This is also important as fieldwork on gathering initial seismic data can only be done during winter months. If not requested on time, any additional or clarifying data may not be available until the following winter. Alas, most of Russia’s hydrocarbons-bearing provinces tend to turn into swamps once the temperatures rise above zero which makes logistics more difficult, seismic data quality poorer and acquisition less efficient.
The whole process from sedning out field crews to conducting seismic acquision is a lengthy and painstaking task, consisting of many stages.
An average seismic crew can shoot about 1000 kilometers of 2D and up to 400 sq.  kilometers of 3D seismic per season. The data includes the rocks and subsurface structures’ reaction to seismic waves created by either explosions or special machines that send vibrations through the ground. It is then turned into a seismic cube with lots of traces in it. It is from these traces that the final color three-dimensional images appear, offering a data rich picture of things deep beneath the earth’s surface.
Improvement in the safety performance of crews working on seismic acquisitions is also one of the company’s primary goals, even if the crews are sub-contracted and not members of TNK-BP staff.
“Before the arrival of BP we didn’t consider it necessary to think about work safety of our subcontractors. We thought that those were their problems. Now, their work safety issues are treated just as seriously as our own,” says Ostapenko.
In addition to allowing experts to “see” through the landmass, 3D technology is effectively a tool for traveling back in time. The final product – a seismic cube – not only helps to pinpoint locations of oil-bearing structures, but offers a glimpse of ancient landscapes. A trained eye can spot paleo-rivers, atolls that once rose within long-vanished seas and even impact craters left by meteorites that hit the planet hundreds of millions of years ago.
“We have got some great images now in Orenburg and the Uvat project in southern Tyumen, where we can see paleo-riversystems and other geological features,” says Einchcomb.
Around Orenburg, TNK-BP’s experts have found pre-historic atolls, while a meteorite impact crater was spotted in the Pulytinsky license.
“There is an example of something that is fully accepted to be a meteorite impact crater in the North Sea. We think we have found something very similar in Western Siberia,” says Einchcomb. “You just recognize it because it’s round and as an impact crater it has a hole in the middle and a very concentric pattern.”
The depth to which 3D and 2D seismic allows oil companies to “see”, varies depending on the geology of a specific region – namely the depth at which the crystalline basement lies where the rocks are generally hard and absorb most of the seismic energy preventing further penetration of the seismic sound or shock waves. That solid rock represents some of the earliest stages of the Earth’s existence dating back as far as the Archaean period – 3.8 billion years ago to 2.5 billion years ago, when life-forms have not yet exceeded the scale of bacteria. In some cases, such as TNK-BP’s Bolshekhetsky project located on the territory of Krasnoyarsk Region and Taimyr Atonomous District, the basement lies as deep as 6-7 kilometers below the surface – a depth which would swallow 18 Empire State Buildings stacked end to end.
The excitement of seeing the images of the long-gone world, however, does not seem to interfere with the main purpose. Better understanding of ancient depositions simply helps to find oil. While for some, being able to tell apart an ancient reef from an ancient platform sounds like an exciting opportunity to look closely at a pre-historic landscape, the truth is – reefs tend to have better reservoirs than platforms.
In another example, TNK-BP experts just recently identified a group of reefs lying some 3 kilometers below the surface at the Peshkovsky project in Samara region.
Dated back to the Devonian era, or some 375 million years ago, when prehistoric fish already inhabited the planet’s oceans and first amphibians were making their first steps on the dry land, those reefs grew in a shallow sea.
Today, however, they can be a perfect reservoir for oil, says Ostapenko, since the reefs appear to have a good overlying seal above them – in simple words a tight lid, allowing oil to accumulate in the porous body of the ancient coral colony.
“They are complex structures and they are not large at all. Without 3D seismic, we would have never spotted them and would have never decided to drill them,” says Ostapenko.
And if a few test wells strike oil, there are usually other similar structures for TNK-BP to explore nearby based on that experience.

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