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October 5, 2007
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Home / Issue Archive / 2007 / September #9 / Transforming the HSE Risk Profile in Land Seismic Operations

№ 9 (September 2007)

Transforming the HSE Risk Profile in Land Seismic Operations

By Allen Balla for Input/Output

_editor_Page_2_image1.jpg Surface access is one of the most important privileges that an E&P company can obtain. For a seismic acquisition company, surface access makes the difference between running a profitable business and not running one at all. Good health, safety, and environmental (HSE) practices, through responsible management of people, vehicles, and surface footprint, can help E&P operators and their acquisition contractors increase the odds of an access grant.
In the early days of 2D seismic operations, land access was not that difficult to obtain. Surface footprints were limited to the extent of a linear line, operations were not especially obtrusive, and a landowner would often see the activity end in a day or two.
As seismic evolved toward 3D, the operational footprint became more noticeable. Instead of a few stakes in the ground and a few flags placed by a couple of surveyors, more people and vehicles covered large swaths of the surface. These factors equated not only to increased HSE exposure, but also to increased landowner sensitivities. Throughout the world, companies often found their requests for access denied and, in the most extreme cases of HSE indiscretions, had their production licenses revoked.

The pressures continue to build

High-quality exploration opportunities have dwindled in many areas, in part because legacy seismic data has often been insufficient to support new waves of exploration and exploitation. Although E&P firms and seismic contractors would like to re-acquire seismic over lands that may have been previously imaged, they are being forced to re-examine their explicit or implicit contracts with the landowners.
In some cases, stakeholders were promised that a single, legacy dataset would be acquired only once, with quality and utility that would be sufficient to last throughout the generations. Given current environmental mindsets and perceptions of broken promises, going back to re-secure access may not be easy.
This re-acquisition pitch is being hindered by the fact that contractors are deploying ever-larger systems to support E&P companies’ desires for densely sampled data. Instead of deploying thousands of source and receiver locations in an individual survey, the industry is moving toward tens of thousands.
Without a re-think of land seismic operations, oil & gas company goals and landowner objectives seem destined to remain out of balance. Increasing station counts will drive greater numbers of vehicles and higher risks of surface disturbance. Moreover, to support these large recording templates, the number of surveyors, line crews, vehicle operators, troubleshooters, and support and management personnel will increase exponentially.
If traditional surveying methods are employed, more stakes and flags will be required, which will increase the trash burden and risks for wildlife and grazing stock. If traditional cable-based recording equipment is used, it will be on the ground longer, due to the time it takes to shoot through the spread and the complexity of troubleshooting and repairing systems that utilize cable-based telemetry.
One can imagine that acquiring the next generation of densely sampled seismic data is going to become a much more “in your face” experience for everyone involved, which will escalate costs for both the contractors and the oil & gas companies, possibly beyond what the resource may economically be worth. No one wins in this scenario.

A new approach – cableless acquisition systems  

To address the apparent conflict between dense sampling and HSE-aware, landowner-friendly seismic operations, one must revisit the entire seismic imaging workflow. At the root of the problem is cable-based telemetry, a legacy our industry inherited from the earliest days of seismic.
Troubleshooting can be the most dangerous operation in seismic recording. For a cable system, a fault often causes large failures of many stations that require an immediate intervention. Troubleshooting or repairing the system quickly becomes an imperative, sometimes at the expense of safe operations. In a cableless system, each recording point operates as an autonomous node; one fault will not bring down the entire system and acquisition operations can continue as planned. As a result, cableless systems promise a major leap forward in HSE performance for the seismic contractor and their customers.
The contrast in weight between a cable-based versus Cableless recording system is astonishing; cableless is only about 20 percent of the weight of large-scale cable systems. In terms of HSE impacts, mobilizing four semi-trucks (cableless) instead of ten (cable-based) to ship gear to the field equates to reduction in both road miles and parking footprint in the staging area, which equates to less fuel use, greenhouse gas emissions, and surface and visual impact.
Less weight also affects transportation at the acquisition site itself. In I/O’s recent deployment of the cableless FireFly® system at Wamsutter for BP, helicopters were used for equipment deployment and retrieval. While the advantages of a helicopter – little or no surface damage, faster and more efficient operations, and fewer people – would accrue in either a cable-based or cableless operation, weight is no friend of air operations. By employing specifically designed heli-bags for FireFly, productivity improved from 24-36 stations per load to 54 stations per load. In future operations, some E&P companies or seismic contractors may choose to further increase the amount of channels per flight.
Weight also affects the productivity and the safety of the layout crews that walk the lines for deployment and retrieval. When using a cableless system like FireFly, the number of bodies in a layout or pickup crew can be reduced from four to two because of the design of the equipment and the hardware, software, and methods used for deployment.
In practice, the average equipment weight carried per FireFly crew member is less than for a typical cable operation, with the recording equipment load starting at 37 lbs for a two-man crew. The carrying bags are designed to be worn on one’s back using a comfortable backpacking frame like those found at REI or similar outfitters. This design frees the hands of crew personnel so they always have a hand free for a potential three point stance, helping them avoid slips, trips and falls. In addition, taking the weight out of their hands also prevents hand and wrist strain.

Software and digital technologies complement the cableless revolution

Field operations are further supported by a new generation of software-based tools which, for FireFly, are sold under the trade name Connex™ and developed by I/O subsidiary, Concept Systems. Key functionalities include optimal survey planning, topographic slope analysis, navigation and positioning, and route planning. Collectively, these help to minimize safety risks and prevent encroachment into environmentally sensitive areas.
One of the more exciting uses of the Connex tool is real-time surveying, sometimes referred to as stakeless or integrated surveying. Stakeless surveys have several advantages, including accuracy, reduction in site visits, reduced costs, and improved HSE risk profiles. Traditional seismic survey operations involve a crew manually marking shot points and receiver and line locations with flags, stakes, and biodegradable paint. Unfortunately, significant delays are often experienced between surveying and acquisition, which allows weather, animals, and human interference to degrade the survey preparations. As a result, multiple visits are often required to mark and quality control receiver and source locations. Whatever the technique, and even if the survey markings did not degrade, there is always the potential for human error in placing the receiver array or positioning the sources.
LiDAR (Light Detection and Ranging) is another technology that is changing the way surveying and acquisition operations are performed.
LiDAR involves taking an air photo (or rather, tens of thousands of them) using a laser beam as the light source. Since it is digital, LiDAR data can be used in various ways. One of the most common is to support development of a digital elevation model of the surface topography.
The elevation model enables maps – including natural and man-made features – to be output in a digital format. When incorporated into route plans, field crews can avoid known obstacles and journeys over topographically challenging areas. The route management system within Connex guides people, shot-hole rigs, and vibrators to their deployment positions along a safe path and with the least amount of visibility and disturbance to the surface. This system also delivers on-line safety briefings and contains a warning system that highlights potential dangers along the route execution.
Based on recent benchmarks at both Wamsutter and the northeast Texas survey for Apache, crews using Connex were moving both more quickly and more safely.

Conclusion

To meet society’s needs for hydrocarbons, E&P companies and seismic acquisition contractors require access to both public and private lands.
As the search for oil and gas becomes more challenging, the latest technologies will be called upon to deliver higher resolution images of the subsurface. To increase image quality and utility, there has been a clear and continual increase in the number of source points and receiver channels utilized on the average land seismic survey.
Unfortunately, this is accompanied by an increase in equipment, personnel, risk to health and safety, and potential for environmental degradation. With landowners increasingly concerned about how their acreage is accessed and by whom, a new approach is required. Fortunately, an emerging set of technologies – centered upon cableless acquisition systems and the software-based enablers that complement them – seem to have arrived on the scene just in time. They promise to restore the balance among landowners, E&P firms, and seismic contractors by delivering densely sampled, HSE-friendly data in a cost effective way.

For more information contact Allen Balla at [email protected].

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