Oil & Gas News
Monday, 31 August 2009
Marine Seismic Survey: The General Principles
Dr. Richard Stocker, PhD, MSc. Senior Geoscience Consultant
Pablo Alvarez, MSc., BSAT. Senior HSE Advisor
VISION PROJECT SERVICES (UK) LTD., Dorset, England.
Any client contemplating a marine seismic program should be cognizant of the general principles for seismic acquisition. The details are also very important but the brevity of this article precludes their discussion. If the client adheres to the general principles, the right consultants and contractors will attend to the details.
All seismic acquisition should flow from well-defined exploration objectives. These are geological objectives translated into seismological objectives, that is, the characteristics and attributes of the finally processed seismic data. They dictate the acquisition design and the technical specifications.
The Contract - Stand-by Time
The best contract is turnkey with chargeable stand-by time. The turnkey provision puts the responsibility on the seismic contractor to be logistically efficient when the crew can work but acknowledges situations out of the contractor's control when the crew cannot. In such circumstances, the contractor should be compensated for the operating expenses. If extensive standby time occurs and the cont
An instrument engineer should conduct a pre-production audit and act as a resource throughout the entire program. Consultants to perform the dockside verifications and calibrations of the positioning equipment and to examine the positioning data from the first acquired data are the norm.
Client representatives for real time verification to ensure the work complies with the technical and HSE specifications. Extensive QC seismic processing or final data pre-processing on board may require a seismic processing client representative.
For marine acquisition the standard is two sets of rotating client representatives, one for seismic and one for navigation-positioning. Commonly the client only requires an initial HSE audit before the vessel leaves port. At sea, the seismic and navigation-positioning client reps have responsibility for overseeing HSE. Some clients may also require a technical audit, which is conducted partly at the dockside, and at sea during the initial deployment of the equipment (energy source and streamer(s))
Selecting Consultants and Contractors
The simple answer is to select personnel who have done a good job previously but this begs the question. For individuals, recommendations from trusted and knowledgeable colleagues who have worked with the people are the best method. Given the gravity of this decision, a telephone interview is warranted.
Selecting a seismic contractor is much more difficult than selecting individuals. Many, if not most seismic contractors have many crews. Not all are of equal quality. The composition of crews change with time. What was a good crew may become less so and vice-versa. Many seismic contractors divide the world into different administrative regions and the regions may not have the same attitude toward HSE and data quality. Every seismic contractor, to hear them speak, is dedicated to world-class HSE procedures and data quality. However, seismic contractors are not charitable organizations. In effect, seismic contractors sell the time of their personnel and rent their equipment to the client. The better the HSE procedures and the higher the data quality, the more time is required to complete the program and often more equipment is necessary. World class HSE and high-resolution data cost more – as a client do not expect something for nothing from your seismic contractor.
The technical and HSE specifications must be part of the package sent to the seismic contractors bidding on the work. How else can the seismic contractors bid appropriately? The client should involve the consultants in writing said specifications. The instrument engineer should comment on the appropriateness and the reliability of the instruments and sensors proposed by the bidders. One seismic contractor may propose equipment with a significant advantage. Remember that the specifications are the "rules of the game" that the "referees", i.e. the client representatives enforce. Poor rules leave the client representatives powerless.
The Acquisition Design
The mantra of all seismic acquisition is acquiring data which meets the exploration objectives at minimum cost. Clearly, this goal cannot be accomplished with imprecise exploration objectives. Even with precise exploration objectives the acquisition design can overdesign or under-design the program. Overdesigning the program means the exploration objectives will be met but the cost will be unnecessarily high. Under-designing the program means the data will at best only partially meet the exploration objectives. The client needs two independent designs to consider.
The seismic industry has made remarkable technological and methodological progress over time. The issue for the client is, do you need the "latest and greatest equipment and/or methodology"? For marine acquisition do you need MAZ or WAZ methodology? If you do, be thankful it is available. If not, it represents overdesign. For an expert and objective discussion of these issues read the books and papers by Gijs Vermeer.
The Technical Specifications
The technical specifications, despite their importance, are the bete-noir of acquisition. Learned treatises, papers and meeting presentations consider acquisition design. Very little public discussion of technical specifications is available. Seismic contractors have their internal specifications but generally are loath to disclose them
Since the technical specifications concern what constitutes lost data and the percentage of lost data that is acceptable, the seismic processor should be the ultimate decider. For example, it is not the signal-to-noise ratio on the raw records that is important but the signal-to-noise on the final processed data. How seriously does a channel failing a particular test degrade the trace? What tests can be failed and still have acceptable data? The instrument engineer knows the effect of a test failure on the amplitude and phase characteristics of the response but only the seismic processor knows if incorporating such data would do more harm than good.
In the field, the observers have to make the judgment whether to record or stand-by in real time. They require numbers for the maximum permissible ambient random noise and how many channels can be above the limit. They need to know what tests to run on the instruments and sensors and what are the tolerances. The instrument engineer has the expertise to advise the client on the tests and tolerances. The seismic processors, given they have at least a sample of the seismic data, know the maximum permissible ambient random noise and how many channels can be above the limit. The recommendations of the seismic processors can then be translated into the numbers required by the observers.
Extensive and Comprehensive Start-up Meeting
An extensive and comprehensive start-up meeting should be conducted after the seismic crew has completely mobilized and just before the parameter testing, Attendees should include the client, client representatives, the instrument engineer if possible, the heads of department from the seismic crew, the party chief, the country manager and the seismic contractor regional HSE and technical gurus if possible. All technical and HSE specifications should be discussed deliberately and thoroughly, and then agreed to as appropriate and doable by all parties.
Parameter Testing - Production Testing
To reduce the expense of parameter testing all relevant data should be analyzed prior to generating an acquisition design. Existing seismic and well data are the most valuable. Clients need to do their homework.
The ultimate parameter testing is production testing. A production test acquires an appropriate interval of fullfold seismic data along a production line and then evaluates the parameters from the fully processed seismic data. The client has either to have the data fully processed on-board or have fast-track seismic processing on shore.
The final concept is that of seismological areas. The optimal values of acquisition parameters for a given seismological area differ from those of adjacent seismological areas. Differences in bathymetry, near-surface and subsurface geology create seismological areas. The larger the program area the more likely there is more than one seismological area. Each seismological area requires a separate parameter and production testing.
Approaches to Seismic - Rational versus Budget-Constrained
The principles stated form the basis of rational seismic exploration in which data meeting the exploration objectives is the independent variable and cost the dependent variable. Hopefully the budget for the project is adequate. Cost is the independent variable in the opposite approach, which may be termed budget-constrained seismic or you-get-what-you-get seismic or hope-and-pray seismic. This approach is quite common, in fact probably the more common. Again, one hopes the budget is adequate, otherwise the data will only partially met the exploration objectives or may not meet them at all. One may contemplate the aphorism that the most expensive seismic data is data that fails to meet the exploration objectives.
Health, Safety and the Environment
For the HSE professional, marine seismic offers the advantage that Safety is an integral aspect of all marine operations following IMO (International Maritime Organization) regulations as well as IAGC and OGP directives on this subject.
All personnel and crew in a boat can only board after following minimum training, which ensures that HSE is part of the marine mind set.
Still, HSE in marine operations is a demanding task. Many sets of regulations must be followed to ensure compliance with "best practices". One example is MARPOL, the International Convention for the Prevention of Pollution From Ships (1973, modified by the Protocol of 1978). Guidelines and regulations are clearly explained there, so the role of the HSE personnel is to manage a complex system, as opposed to implementing one.
Training and drills are also clearly stated and scheduled. That leaves the HSE personnel the freedom to concentrate on the quality and effectiveness of the training program, as opposed to whether these drills are performed (or which ones should).
Still, high seas operations are complex scenarios. In streamer marine jobs, the handling of the heavy equipment poses clear dangers. Proper planning, from fully fledged operations (those that are not routine) to the daily "Tool Box Meetings" must be carried out, and documented. The TBM's can be used specifically for planning and reviewing procedures, which may have a higher level of risk if the crew begins to see them as routine and "easy". It is the role of the HSE professional and Heads of Departments to foresee problems that break with this routine and can lead to incidents.
In Ocean Bottom Cable (OBC) jobs, the key issue is the use of several different types of crafts. HSE must ensure that different regulations and levels of seaworthiness mesh together, and that maintenance and safe practices cover all procedures. OBC also calls for land bases, mixing both land aspects with marine. This usually leads to duplicate or "extended" HSE departments.
These must ensure that emergencies in both land and sea are taken care of while not relying on the same personnel and services. The intrinsic spreading of personnel, crafts and equipment over both sea and land make these operations more complex than the Streamer jobs, calling for a more detailed planning of the initial aspects of the operation, as well as the day to day after the job has started.17:02 2 Comments
Auramarine - new challenger in the market for ballast water treatment systems
Auramarine Ltd is the world's leading manufacturer of heavy fuel oil supply systems and other auxiliary units for marine and power station engines. The company is now applying its wide-ranging experience in liquid flows to a new sector that benefits the environment.
Auramarine is bringing out Auramarine Crystal Ballast, Ballast Water Treatment System (BWTS). Thanks to technological innovations featured in this system, it is energy-efficient, compact and easy to install. Additionally, Auramarine's solution does not affect the time required for ballasting or de-ballasting operations, or increase the duration of port calls.
With Auramarine Crystal Ballast, extremely promising results have been obtained. The project is currently entering an intensive type approval testing phase. It is progressing on the projected schedule, and the first system type approvals and final products are expected to reach the market in the second half of 2010. With this novelty product, Auramarine is aiming for a remarkable share in the BWTS market. Up to year 2019, the market potential is estimated to be substantial, as around 50,000 ships should be equipped with BWTS.
Broad understanding of ballast treatment
Auramarine has dedicated significant amounts of time and funds to develop a BWT System that can cope with the requirements of various ships and harbours. In the Crystal Ballast project, Auramarine had four main goals: the company was determined to provide the best practical solution for shipowners and yards around the world. The project also strived for comprehensive understanding of ballast water conditions and flows onboard ships, and aimed at a system that could be adjusted and fitted for various vessel types and ballasting operations. Finally, the product had to be competitive as regards its size, weight, energy consumption and cost-effectiveness, both at the time of installation and in operation.
UV-C - ballast water treatment of the future
Auramarine's solution is based on utilising UV-C radiation. The UV-C solution presents indisputable advantages, and the technology concerned is already familiar from such as treating drinking water and wastewater. The advantages of using UV radiation as a disinfection process are clear. This purely physical disinfection process has been tried, tested and proven in many land and marine applications. No harmful by-products are formed in the process, nor does it require the production or storage of chemicals on board. The system presents no danger of overdose or underdose, as only naturally occurring processes are used. The process does not result in any changes in the physical parameters of the water, such as its pH value, temperature, salinity, taste, odour, or colour, and a system based on UV-C technology has a relatively low overall energy consumption.
Destructive invasive species continue to spread with ship ballast waters
Every year, states and the fishing industry incur costs amounting to millions because of alien species that are carried from one water system to another in the ballast water of ships. In February 2004, the International Maritime Organisation (IMO) adopted a convention that aims at controlling the spread of harmful alien species carried in ballast waters.
The only way of restricting the further spreading of invasive species through ballast water is to ensure that all states ratify and implement the BWM Convention, and all vessel operators fit appropriate technology on all ships.
About Auramarine LtdAuramarine is the world's leading supplier of auxiliary equipment for large diesel engines and turbines. Auramarine products are designed and manufactured to suit all major diesel engines available as marine power sources today. Another customer segment of the company is the diesel based power station industry worldwide. A steady and dependable supply of electricity is of major importance for any power station, and Auramarine products play a crucial part in providing this supply. The total number of skid mounted auxiliary units produced is well over 9,000 since their production begun three decades ago. posted by The Rogtec Team @ 16:26 0 Comments
Friday, 28 August 2009
Russian onshore seismic acquisition
Integra is one of the world's leading geophysical companies with over 40 crews operating in Russia and Kazakhstan as well as having an international presence. In Russia, the company's subsidiary, Integra Geophysics, is one of the leading companies by volumes acquired and Azimut Energy Services, it's Kazakhstan subsidiary, leads the industry in acquisition volumes. The company has acquired 2D and 3D seismic surveys for all of Russia's leading oil companies (Gazprom, Rosneft, LukOil, TNK-BP etc) and in Russia and Kazakhstan has a growing reputation with international oil companies like ENI, Shell, Chevron and BG after acquiring major 3D surveys over some of the world’s largest oil and gas fields.
Since 2006 Integra has been investing in new equipment and technology to improve health and safety (HSE) and operational performance. The result is that that the company is now equipped with some of the most advanced geophysical equipment available including a fleet of modern ION and Sercel vibrators and recording systems. This allows Integra to compete with some of the world's leading geophysical companies and implement technology routinely used in other areas of the world.
In the summer of 2008 Integra Geophysics conducted a heli-portable seismic operation for TNK-BP in the Uvat region of West Siberia. The objectives of the survey were to improve operational efficiency, reduce the impact of seismic operations on the environment and test the viability of summer operations in areas where winter acquisition is the norm. Helicopter seismic operations are widely used in Canada and the USA to over come logistical challenges in mountainous terrains. Equipment is moved by helicopters thus reducing the need for heavy cross-country vehicles which can cause a long lasting impact on the environment.
The absence of helicopters suitable for heli-portable operations in Russia meant the company had to work closely with service provider UTair to acquire 2 AS350 helicopters and access Canadian pilots to train their Russian counterparts to conduct operations. Equipment required to carry large amounts of ground equipment and slings and hooks to allow helicopters to pick up equipment on the fly was also acquired. Restrictions on satellite receiver technology to help with positioning limited the full impact of operations.
The Uvat region is heavily forested and requires a significant amount of tree cutting. Typically shot and receiver lines are cut to a width of 4 metres to allow the passage of cross-country vehicles and tree-cutting is both labour intensive and a significant HSE risk. In summer, the region is very boggy and the movement of vehicles causes deep ruts and restricts movement. The use of helicopters allowed Integra to reduce the amount of tree-cutting and limit the use of vehicles thus reducing the impact on the environment.
In the Uvat region helicopters were used to move geophysical ground equipment and demonstrated nearly a 2 fold increase in productivity measured by the average number of shot points acquired per day with a daily maximum of over 700sps/ day. The increased costs of helicopter operations can be offset by increased efficiency and reductions in vehicles and personnel. Future operations could be extended to include movement of drilling equipment as well as seismic recording equipment.
Over the last few years the biggest contributor to seismic industry fatalities and injuries was tree-cutting. The industry cuts a significant volume of trees every year, approximately 300,000 line kilometers, and tree-cutters are exposed to significant HSE risks due to falling trees and debris. The efficiency of seismic operations is also dependent on the quality of line preparation. Typically tree cutting operations are carried out in summer to ensure residual tree stumps are cut to a minimum - stumps visible above winter snow cover often limit the movement of drilling equipment. The disposal of cut trees and debris is both time consuming and a requirement to allow the safe passage of vehicles. This adds to the time and risk of manual tree-cutting operations.
In 2007, Integra purchased a mulcher to test the efficiency and suitability of equipment regularly used in other areas of the world for tree-cutting. The equipment was deployed on the same summer project as the heli-portable operations in the Uvat region. The advantage of mulchers is that the number of people involved in tree-cutting operations is reduced from a typical 5 man manual tree-cutting crew to a single operator who is totally enclosed in a safe cabin. The machine effectively "pushes-over" trees and a series of teeth, on a rotating drum, chop the fallen trees in to a fine mulch of wood chips that are deposited behind the machine.
The deployment of mulchers has demonstrated a significant reduction in HSE incidents on tree felling operations with no incidents to date. The effectiveness of mulcher operations has also been proven with a single mulcher capable of clearing between 4-5 kms/day compared with a typical 1km average for a tree-cutting brigade. The advantage of the debris left after mulcher operations is that it provides a flat surface through the cut line that allows a safe and efficient "road-way" for drilling and seismic recording vehicles to follow. A further advantage of a better roadway is that there is less stress on cross-country vehicles and therefore reduced equipment failure and maintenance.
Average operational costs for mulchers and manual teams are comparable but reduced camp sizes and lower HSE risks demonstrate the benefits of such technology. The down-turn in North American seismic market means operators in Canada and the USA are now able to offer high quality machines suitable for the Russian terrain and climatic conditions. Now many leading seismic operators are now looking to stimulate the Russian contracting industry to provide a significant volume of mulchers for the 2009-10 winter season.
High productivity vibroseis acquisition
Approximately 50% of Integra's projects use vibroseis seismic sources. These are commonly used on the flat terrains of the Russian tundra and Kazakhstan Steppe. Individual vibroseis shot points typically use 4 vibrators simultaneously vibrating for up to 20 seconds, known in the industry as a sweep. Oil companies normally request up to 4 or 6 sweeps per shot point. Average survey acquisition rates for Integra operations are between 250 - 300 shot points per day. Daily productivity can be as high as 400 - 500 sps / day depending on weather conditions and terrain. Standard 3D seismic surveys require the acquisition of 20 - 25,000 shot points which will generally take 3-4 months to acquire - the normal duration of the Russian winter season.
Globally, acquisition companies have started to deploy multiple fleets of vibrators and significant volumes of ground equipment to increase vibroseis productivity. This means oil companies are able to acquire larger surveys or high data density coverage during a single operating season. In 2009 Azimut Energy Services has been contracted by a consortium of oil companies to conduct a 3D seismic survey requiring over 250,000 shot points in a area of complex field infrastructure. At typical acquisition rates this would normally take over 2 years to acquire but the consortium's requirement was to acquire the entire data set in 2009.
Working closely with the operator, Azimut was able to design a survey that could be completed within 9 months. The requirement was to utilize up to 10 vibrators, 18,000 channels and 19,000 geophone groups. With it's combined Russian and Kazakhstan resources the company was able to offer the consortium top quality HVA-IV ION vibrators and Sercel 428 ground equipment. The survey design called for 4 groups of 2 vibrators working in both flip-flop and slip-sweep acquisition mode acquiring a single sweep at each shot point. The chosen deployment of the vibrator groups allowed simultaneous operations with some groups vibrating and acquiring data whilst others travelled to a subsequent shot point. 18,000 channels were deployed in the field with an active spread of 9,900 channels. The 428 central electronic system was upgraded to handle the large active spread and new communication equipment acquired to allow the central electronics to "manage" the vibrators and distribution of the channels in the active spread.
The current operations are impressive and have almost certainly set a record for daily production in Russia and Kazakhstan. To date over 100,000 shot points have been acquired in just over 2 months with an average daily productivity of -1700 sps / day. The highest productivity achieved to date was just under 2900 sps / day, the equivalent of 6 seismic parties under normal conditions.
The handling of such daily volumes and advanced electronics has not been without its challenges but the experience gained on this survey will allow Integra to offer advanced acquisition technology to oil companies in Russia and Kazakhstan and allow it to compete globally with western seismic acquisition companies.16:03 0 Comments
Finding Petroleum in The Digital Oil Field
Much is made of the fact that the oil & gas resources of our planet will last many more decades: this is evident if one digs into the most recent BP annual Statistical Review of World Energy. It is also true that much of this petroleum still needs to be found, whether in new discoveries or upgrades of existing discoveries or increases in the recovery factor of currently producing fields or even in the resurrection of currently abandoned fields.
Finding Petroleum in the future will take us to tougher areas, more complex geology, more difficult reservoirs and, unless we are very smart, much higher Finding Costs. It would be wrong, ironic and a great shame if, as companies increased expenditures coming out of the current downturn, they find less barrels and molecules due to tough problems and rampant oil field service prices!
In currently producing fields, this translates into inventing the most efficient and effective way of finding additional petroleum. After all, there is an old adage which says "the best place to look for petroleum is in a producing field!"; in technical terms, this equates to increasing ultimate recovery factors from where they might be perceived to be today, say 25-30%, to 60 or even 70+%.
In my opinion, for many oil & gas companies the best way to do this will be to simply adopt The Digital Oil Field in all its aspects. For some excellent insights into this concept, I refer you to a presentation by David Latin of BP. You can also find a detailed description of BP's Field of the Future concept on the company's web-site.
However, there is a risk that in the current economic climate, installation of a Digital Oil Field, entailing heavy upfront capital expenditure for long-term operating benefit, may be seen as an expensive luxury. This is an understandable if not entirely sensible view point: we are in "Hard Times", not because oil & gas prices are desperately low but because the lesson we have learned from the volatility of the last 12-18 months is that future oil & gas prices are desperately uncertain.
Nonetheless, the right question is – how do we dramatically reduce the costs of the Digital Oil Field so that installation makes sense at (almost) any oil or gas price?
Let's focus on one of those technologies that is especially relevant to the recovery factor question, namely seismic monitoring. How could we ensure that it makes economic sense to shoot 3D seismic - and repeat 3D, also known as 4D - on any producing oil/gas field in Russia and the FSU? Drawing on lessons from the proliferation of 3D seismic technology in the 1990's, the key seems not to attack prices directly but to focus on significant reductions in cycle-time, that is, the time between planning a survey and obtaining a useful sub-surface interpretation that finds areas of un-swept petroleum. In other words, faster led, and will lead, to cheaper and better.
It seems pretty clear how not to do this. Old-fashioned onshore acquisition techniques, involving cutting swathe after swathe through the tundra or the wheat fields and armies of men lugging vast quantities of cable around, up mountains, across roads and rivers, through swamps, seem like - and should be - a thing of the past, on efficiency, effectiveness and HSE grounds. Likewise, ultra-high-resolution techniques - no matter how unique their inventors might think they are - do not seem to be the way forward either, although it would be interesting to see authenticated cycle-time and cost/sq km comparisons published, perhaps on the InterNet.
Instead, we should be looking to the wireless, cable-less systems on offer from ION, OYO Geospace or iSeis, and the innovative approach to sources advocated by Ian Jack.
I have documented evidence from the previously mentioned offshore 3D history that an intense focus on doing things faster will lead to cheaper (dramatically reduced unit costs), in turn meaning that many more, bigger, 3D surveys will be commissioned.
Contractors should therefore see this as a golden opportunity to take part in the dramatic growth of onshore 3D and 4D rather than as a threat to their established systems. 14:33 1 Comments