Data handling key to success of major seismic surveys

Paul Boughton

Thanks to improvements in data handling, many of the latest seismic surveys - from the Seychelles and the Falklands to Iraq and Albania - are revealing promising oil and gas reserves. Eugene McCarthy reports.

Australian energy company WHL Energy says that the largest seismic acquisition survey programme ever conducted in the Republic of the Seychelles, comprising a 19,609 km 2D seismic survey (143 lines), has been successfully completed by Fugro Data Services and Geomahakarsa.

This survey, using the vessel Geo Artic, was conducted on a collaborative basis with the Republic of the Seychelles. In total WHL Energy commissioned 7887 km of 2D seismic acquisition (of the total) over 16 leads found within its large Seychelles holdings. Initially WHL Energy had only intended to acquire 7000 km of 2D seismic, however the board commissioned the acquisition of further 887 km based on the positive results following the initial seismic data review and an independent expert report from Isis Petroleum Consultants.

Isis' studies have confirmed the potential of 12 leads across four different plays in WHL Energy's Seychelles exploration holdings and estimated that these leads have the potential to contain unrisked mean oil in place of between 166m and 5.44b bbl/lead.

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WHL Energy chief executive officer David Rowbottam commented: “The 2D seismic acquisition campaign over our project area is now complete and we expect to receive all required data within the coming weeks, at which time interpretation will begin. Interpretation of that highly valuable data will enable the company to aggressively progress the refinement of key drilling targets for a proposed farm-out in early 2012 ahead of the drilling programme targeted for late 2012.”

Meanwhile Desire Petroleum, a company wholly focused on the North Falkland Basin, has advised that its 3D seismic operations are ongoing with the Polarcus Nadia vessel, in a joint programme with Rockhopper.

To date, approximately 1485 km2 of data have been acquired in the Desire operated part of the programme. The company anticipates that a further 195 km2 will be acquired to complete the programme. Processing of the new seismic data is in progress and initial indications are that data quality is good.

Priority areas have been identified in the East Flank play between Ninky and Sea Lion, and over the Ann/Orca South prospect. The processed data from these priority areas is expected to be available in July. The full, merged data will be available later in the year, which will provide coverage over the southern part of the East Flank play and the Helen prospect.

Desire remains optimistic that existing prospects can be significantly de-risked using the new seismic data and that new prospects will be identified, particularly within the East Flank play which is widely developed within the Desire operated licences.

Company chairman Stephen Phipps commented, "On completion of the Ninky well, Desire will have funds of circa US$37 million which, while more than adequate for our share of rig and vessel demobilisation, completion of our 3D seismic acquisition, processing and interpretation plus general working capital needs, is insufficient to drill further wells. Given our continuing confidence that oil will be discovered on Desire's acreage, further wells will need to be drilled and, therefore, once the results of the Ninky well and the 3D seismic have been analysed, we will review all financing options available with the intention of rejoining the drilling campaign later in the year if possible".

OMV has discovered gas on the North West Shelf of Australia in the Zola-1 exploration well. This represents one of the largest gas discoveries by the company. Zola-1 is located in the WA-290-P exploration permit and is around 100 km from the Western Australian coast.

The discovery well Zola-1 and the subsequently drilled sidetrack appraisal well Zola-1/ST-1 have confirmed the existence of sandstone layers with 130 m of net gas pay in an area south of the giant Gorgon gas field. New 3D seismic data will be acquired to further assess the potential of the discovery.

The sidetrack appraisal well to the original Zola-1 discovery well was drilled down to a total depth of 4713 m (true vertical depth). An extensive wireline measurement and pressure testing programme confirmed the presence of gas within several high quality sands of the target Triassic Mungaroo Formation. The well and sidetrack were drilled in a water depth of 285 m and encountered 130 m of net gas pay. Both will be plugged and abandoned as per plan.

In order to further assess the development potential of Zola, OMV and its partners in WA-290-P, Apache (operator), Santos, Nippon Oil Exploration and Tap Oil, have agreed to acquire a new high resolution 3D seismic survey over the permit, which is likely to commence shortly.

Jaap Huijskes, member of the OMV executive board responsible for exploration and production (E&P), stated: “Zola-1 is one of OMV's biggest gas discoveries and is the result of a successful and safely carried out exploration and appraisal drilling campaign. We are very proud of OMV's exploration activities in Australia, which have culminated in this significant discovery on the North West Shelf. The next step will be to further appraise the gas discovery, including the acquisition of a new 3D seismic survey."

Beach Energy and its joint venture partner San Leon Energy have commenced an 840 km2 3D seismic survey in the Durresi Block, offshore Albania.

San Leon is operator of the joint venture and, through a subsidiary, holds a 75 per cent interest in the Durresi block with Beach holding the remaining 25 per cent. Beach has agreed to pay 50 per cent of the seismic programme costs, rather than its 25 per cent working interest requirement, in exchange for an option which, if exercised after review of the seismic data, will give Beach a 50 per cent working interest in the licence moving forward.

Petroleum Geo-Physical has been contracted to carry out the survey using the Ramform Vanguard seismic vessel. The 3D seismic programme will evaluate a number of prospective targets in the Durresi Block, including the A4-1X discovery, in preparation for drilling in 2012.

The A4-1X gas condensate field was discovered in 1993 and is located 30 km off the southern coast of Albania. San Leon estimates the discovery to contain approximately 38m bbl of circa 51 API condensate and 150b ft3 of gas. The joint venture is also exploring potentially significant oil and gas targets adjacent to A4-1X.

The Durresi block is situated on the proven Apulian Margin, which extends from Italy into Albania. Southern Albania contains a highly prolific petroleum system, including one of the largest onshore oil accumulations in Europe, the Patos-Marinza field, which is estimated to contain up to 5.7 billion barrels of original oil in place.

Gazprom Neft has completed a 3D field seismic survey at the Badra deposit in Iraq. The Iraqi Oil Exploration Company (OEC), who Gazprom Neft contracted in November 2010, carried out the seismic survey.

The survey was conducted over an area of 165 km2. The processing and interpretation of the data received is scheduled for completion in November 2011.

The Badra deposit is located in an area with a challenging profile, with a significant part of the field surface requiring the clearance of mines. During the preparation for the seismic profile, work was carried out to remove weapons over an area of approximately 12 000 km2.

Finally, ARKeX has begun a BlueQube Marine gravity gradiometry survey in the Red Sea. The survey for Saudi Aramco covers three blocks off the western coast of Saudi Arabia.

 The objective of the survey is to assist oil and gas exploration by improving the definition of the top and flanks of salt bodies within the survey area (Fig. 1). The BlueQube gravity gradiometry data will be used to enhance geological and velocity model building to improve 3D seismic imaging. The contract was signed in conjunction with the Shoaibi Group, a leading Saudi Arabian oil and gas technology and service provider, who will be providing commercial assistance on the project.

Surveying on the first block has already commenced and all three blocks should be completed by the end of Q2 2011, after which the vessel will be available for follow on work in the area.

CGGVeritas breaks data transmission record

Text: CGGVeritas has announced that its equipment subsidiary Sercel has broken the seismic recording channel capacity barrier with the launch of the Giga Transverse. The new Giga Transverse is offered as an add-on set of equipment to upgrade the channel capacity of the Sercel 428XL land seismic acquisition system. It is of particular benefit for SuperCrew high-channel-count surveys.

According to the company, the new Giga Transverse boasts the fastest transmission rate in the industry, increasing the new optical transverse cable’s capacity from 10,000 to 100,000 channels in real time per line. With this outstanding quantitative step-change, Sercel says it is in a stronger position than ever to meet the challenges set by the ever increasing capacities of SuperCrews for whom crossing the one-million-channel milestone is no longer a dream but a fast-approaching reality.

With the higher channel capacity, higher transmission rate and simplified deployment offered by the addition of the Giga Transverse, the performance of the 400 series, which is the undisputed leader in land acquisition with a worldwide installed base of three million channels, is further enhanced.

Sercel ceo Pascal Rouiller said: “We are pleased to announce this breakthrough in land acquisition, which is particularly critical for the growing SuperCrew market for high-density wide-azimuth acquisition. With the addition of the Giga Transverse, the 428XL is truly the most flexible acquisition system in our industry.”

Fig. 1. The survey will improve the definition of the top and flanks of salt bodies within the survey area.

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