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Adaptive Approach to Seismic Acquisition as a Method for impoving Efficiency in the Development of Oilfields

by Alena Lipyavko | Oct 01, 2013

Oilfield Services No.1 2013

Russia’s capabilities in seismic exploration are quite impressive, but they are not utilized even to 50%, while the role of seismic acquisition continues to increase with the growing complexities in the geology of projects (both in new and old production regions). Essentially, seismic exploration in the oil industry can be compared to diagnostics in healthcare. The quality of a diagnostics is instrumental in  successful treatment, allowing to save on costly drugs or operations.

Over the years, leading oil and gas companies have relied on the so-called adaptive approach to seismic exploration, which includes a tough audit of competing companies based on a detailed audit of the technical level of their seismic operations, their experience, productivity, and the skills of their personnel. Based on the results of this selection process, a contract is signed between the contractor and subsoil user for three or more years. This has allowed to ensure maximum efficiency in the exploration of fieldы, at minimum costs. This is the reason why such an approach can also be implemented in Russia, where they often lead to savings in exploration.

  RUSTAM RAKHMATULIN
Senior Vice President, Sales and Marketing, CJSC GEOTECH Holding

Oil and gas exploration is a challenging business both from the technical and methodological points of view. Hydrocarbons exploration is always coupled with significant and, at the same time, objective risk. It is no secret that the scope of exploration activities in today’s Russia is significantly lower than it was in Soviet times. The rate of resource replenishment is extremely slow: a huge under-exploration of Russian resources is evident. This applies both to new (Timano-Pechora, Eastern Siberia) and traditional regions (Western Regions, Ural-Volga region, etc.).

In addition, the unallocated oilfields in our country currently include mainly small or medium-sized fields, with almost no large fields. This is an indication that, although the quality of seismic exploration since Soviet times has improved, the level of activity (taking into account the number of active crews in Soviet times and now) has significantly shrunk.

Yet, the quality of seismic surveys even today raises a host of questions. It is known that success in drilling in each specific case directly depends on the quality of the seismic surveys conducted on the field. This success does not always come with the drilling of the first exploration wells. There are a lot of examples of dry drilling both in Russia and all over the world. There is also such a parameter as the drilling success ratio, which is estimated as the ratio of discovered fields to the total number of targets evaluated by deep E&A drilling.

Globally, on average, this coefficient stands at around 0.3-0.5. In other words, only every third drilled target is a field and one should to take into account the toughening requirements for preliminary pre-drilling preparations.

Surely, 0.3-0.5 is a rough approximation of available data. Actually, each region has its own success ratio and in each region it varies in time and can vary as resources are developed. However, one way or the other, the drilling success ratio is an indication of the quality of seismic exploration.

Adaptive Approach

Currently, seismic exploration is considered the standard method for the exploration of hydrocarbon deposits. But, in effect, it is a range of methods of field exploration and subsequent processing and interpretation of data.

The capabilities of modern seismic exploration allow a subsoil user to make assumptions that are appropriate for his geological tasks, budget and needs. Evidently, this increases the responsibility of the seismic exploration company and its customer and, therefore, requires much closer technological cooperation between the parties than is actually the case.

Currently, in most cases, seismic crews operate as a blind tool: a company obtains technical specifications and has to strictly follow them.

In these conditions, the contractor is interested only in formal compliance with a customer’s requirements, but not in the final product, which often has the most serious consequences for further development of a field.

This is why, given the gradually increasing complexity of the geology of developed fields and the toughening requirements contractors and subsoil users have to meet, a complete overhaul of the current Russian approach to seismic exploration is necessary. Streamlining this process will allow customers to quickly enjoy benefits from the implementation of projects and will ensure long-term improvement of quality in exploration in general.

 Competitive Selection

What does this include? First of all, it includes a toughening of the qualification requirements on contractors. Actually, this implies abandoning the formal (money-based) principle of selection of contractors and the introduction of a complete and objective audit of competitors before selection. This particularly applies to major and challenging projects that require a more responsible approach to services, higher level of technical expertise from the contractor, and experience in project  management. It helps to keep in mind that selection of a bad contractor is akin to a time bomb: the damage caused by the poor quality of the work of the seismic exploration crew can be much greater than the cost of the seismic exploration, because such a contractor is accountable for all the mistakes made based on the conclusions drawn using the results of a poorly performed seismic acquisition. At the same time, seismic exploration accounts for only 5-10% of the total exploration budget.

Long-Term Contracting

The second component is the conclusion of long-term agreements (for three or more years) at fixed prices. This will allow to minimize a subsoil user’s expenses, a significant part of which are spent on excessive mobilization because contractors change every year. It will also reduce additional costs related to rush preparation. Evidently, all these expenses are included by contractors in the offer price during the evaluation of a project’s cost. A long-term contract allows to obviate such costs. At the same time, it reduces the risks of a subsoil user related to unexpected cost increases, since prices are fixed for the entire contract period.

Until the long-term contract expires, the scope of the work is provided without a tender and/or based on a simplified procedure by signing a work-order or an additional agreement.

High Productivity

Another prerequisite for achieving positive results in seismic exploration is maximizing the capabilities of the contractor, so that he uses time efficiently, since time  is in essence the only really non-renewable resource.

The work season is always limited (from November to March), and it is extremely important to collect a maximum amount of information within this limited time spell. This is why at the planning stage the focus should be on the productivity of a contractor and his understanding that a customer primarily is interested not in the fact of completion of the seismic survey but in the result, which is expressed in the collection of deposit structure and field geology data with maximum reliability.

It is necessary to note here that modern seismic exploration in other countries has already removed all limitations on productivity: today, it is better to make 200,000 physical observations of relatively lower quality in one project than to make 20,000 higher quality physical observations. The application of modern mathematical methods and software in the processing and subsequent interpretation of these data will allow to achieve positive results (high-quality seismic records) and will reduce the percentage errors  in subsequent drilling.

No doubt it is also necessary to maximize the diversification of field seismic acquisition, data processing, and interpretation methods by adapting them to the specific tasks of a customer. Additionally, seismic exploration companies need to be engaged as early as at the planning stage to maximize the output of a seismic exploration. The contractors, in addition to advanced equipment, should have good knowledge of the operational conditions in the survey regions.

Appraisal of Old Fields

Today, the modern capabilities available in seismic exploration should be used not only in greenfields, but also in brownfields in order to update past seismic data. This will enable to conduct follow-up exploration of brownfields both for the exploration of bypassed structures which were not found due to the low resolution of the methods that were then used and for exploring other horizons to map their reservoir properties to ensure more efficient spudding of development wells on drill pads.

Practically, the application of all of the abovementioned principles on the one hand will ensure more efficient seismic exploration for customers and, on the other hand (through an adaptive approach and improvement of the drilling success ratio), will reduce overall exploration costs and increase investment efficiency for many projects now frozen due to high exploration risks.