EXPERTISE

• Regional studies
• Reservoir studies
• Horizontal well monitoring

• Predrill studies
• Horizontal Wells
• Post-well studies

The stratigraphic team at Network Stratigraphic Consulting Ltd. has over 100 man years industrial experience, ranging geographically around much of the world, including most of Europe, Africa, the Middle East, South America and the Far East. Click here for more information.

This group of stratigraphers has an excellent background in both routine and high resolution stratigraphic studies having been actively involved in everything from wellsite biostratigraphy in frontier exploration areas through to detailed multidisciplinary multiwell studies in mature petroleum provinces.

Currently staff are involved in a number of active field development campaigns, carrying out wellsite biostratigraphy on a continuing programme of horizontal wells with additional follow up analyses to complete full stratigraphic reports. Other studies include:
- routine well analyses,
- high resolution intra-reservoir correlation projects,
- regional sequence stratigraphic reviews,
- evaluation of old biostratigraphic data/reports,
- quality auditing of existing biostratigraphic zonations
- detailed Tertiary studies as part of regional overburden evaluations.

It should also be noted that we have available to us a very experienced team of contract wellsite biostratigraphers, specialising in the monitoring of both exploration wells and horizontal production wells throughout the Paleogene succession and into the Mesozoic sequence. The latter is a particular specialist area for Network Stratigraphic Consulting Ltd., primarily in carbonate field development in the Norwegian and Danish offshore. All staff are fully qualified technically, as well as carrying all the requisite health and safety certification for work in the North Sea region (UK, Denmark & Norway).

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Regional studies
In 1998 Network Stratigraphic Consulting Ltd. was invited to review the Late Cretaceous Chalk stratigraphy of the triple point region of the Central Graben. Results of this multiwell study were presented to the JCR meeting in 1999 and published by the Norwegian Petroleum Directorate.

Network Stratigraphic Consulting Ltd. staff have carried out field wide studies on Ekofisk, Eldfisk Alpha, Eldfisk Bravo, Valhall, Hod, South Arne, Joanne, Hanze, in addition to other multiwell studies in the Danish and German offshore.

Reservoir studies
These take many different forms and are not simple well to well correlations. On Valhall we produced the first wellsite manual documenting the full involvement of biostratigraphy and its use in field development. On Ekofisk we have carried out detailed biostratigraphic studies on all the available core across the field. On Eldfisk we have undertaken biofacies studies in order to establish the variations in chalk sedimentation and its effect on reservoir properties. Biofacies studies have also been carried out on various stratigraphic units of the Miskar and Hasdrubal Fields in Tunisia.

We have completed a 34 well review of the Narve (=Hod) Formation in the Valhall Formation integrating biostratigraphy with petrophysics for the first time to create a geological model.

Horizontal well monitoring
Over 200 wells drilled to date on the Valhall, Ekofisk, Eldfisk and South Arne fields has used Network Stratigraphic Consulting Ltd. biostratigraphers at the wellsite.

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Predrill studies
The most efficient and productive horizontal drilling programmes are those which utilise all the hard work which has previously been put into appraising the field. A huge amount of data will already exist; this needs synthesising, supplementing and building into a viable stratigraphic model.

South Arne – Before the horizontal drilling programme started Network Stratigraphic Consulting Ltd. re-evaluated all the data from the exploration and appraisal wells drilled on the structure (I-1, Baron-2, Rigs-1 & Rigs-2). A Stratigraphic Model was developed which could be used and would evolve during the horizontal drilling programme.

Hanze – The Hanze field in offshore Holland benefited from a multiwell biostratigraphic appraisal study in order to identify the principal producing biofacies prior to horizontal drilling.
Ekofisk – During the early phase of horizontal well drilling on Ekofisk, a biostratigraphic re-evaluation of every previous report and all the available cored section from the reservoir was undertaken. The value of good quality data cannot be underestimated.

Miskar – Much of the production from the Miskar field comes from the Campanian – Maastrichtian Abiod Chalk Formation. In addition to this additional production from the calcispheric chalky limestones of the Turonian Bireno Formation is being evaluated with the view of establishing a Stratigraphic Model for use in biosteering horizontal wells through this secondary reservoir.

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Horizontal Wells
Network Stratigraphic Consulting Ltd. has carried out almost 200 wellsite projects since the company was established in 1994. Of these projects, approximately 80% included monitoring and biosteering horizontal wells.

Prior to the establishment of the company in June 1994, our staff were involved in all the horizontal wellsite work on the Ekofisk, Eldfisk, Valhall and Hod fields.

Staffing a horizontal well requires a two-man team working twelve-hour shifts. They carry all their equipment with them, including microscopes and laptop computers allowing sample processing, analysis and reporting.

Valhall – First with Amoco Norway and since January 1999 with BP Norge, Network Stratigraphic Consulting Ltd. biostratigraphers have been directly and intimately involved in development drilling on the Valhall and the adjacent Hod fields (over 70 wells). The reservoir sequences are zoned biostratigraphically, each zone and subzone being defined by its own suite of nannofossils and other microfossils.

Ekofisk – Network Stratigraphic Consulting Ltd. staff provided wellsite biosteering on the first horizontal producer on the Ekofisk field drilled in 1992 by Phillips Petroleum. Since June 1994 all horizontal wells on the field (total – 38) have utilised wellsite biostratigraphers, working with an evolving stratigraphic model for the field that is closely calibrated with the Reservoir Zones.

Eldfisk – Since June 1994, a total of 42 horizontal wells have been drilled on the Alpha and Bravo structures using Network Stratigraphic Consulting Ltd. wellsite staff. In addition to this biostratigraphers have also assisted in casing picks.

South Arne – Network Stratigraphic Consulting Ltd. has been involved in the development of the South Arne field in Denmark since its very beginning. Staff helped to develop the Stratigraphic Model and have been on all 19 horizontal wells drilled since the spudding of SA-1 in the summer of 1998.

Satellite structures - wellsite biostratigraphers have also been employed during the evaluation drilling of satellite structures, including Nokken (2/8-15), Trud (2/8-17), Modi- 1, Ebba and Embla, etc.

Other wellsite work includes horizontal wells on the Maureen Field, Hod Field and Tor Field as well as numerous development wells in the Greater Britannia area.

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Post-well studies
Infill analyses – following wellsite studies, infill micropalaeontology and nannofossil analyses are carried out regularly in order to provide a full cover of the whole well for both disciplines. This allows for those times when staff are working shifts offshore. Full reports are produced on all wells studied offshore.

Multiwell correlation studies – it is a simple exercise, with the Stratabugs software used in-house, to collate multiwell correlation panels showing important biostratigraphic marker events, wireline logs, etc.

Field review studies – horizontal wells generate a vast amount of very useful data that can be used in evaluating associated aspects of the field. Working and collaborating with other specialists (geophysicists, sedimentologists, etc.) We can help to ascertain facies studies, sedimentological variations, structural history, faulting, etc.