TRENDS: CONTRACTORS' CHALLENGES, ABILITIES

Mark H. Houston
Halliburton Geophysical Services
Houston

The fortunes of the geophysical industry in the U.S., as measured by the crew count, look like the Dow Jones averages with its historical ups and downs, with one exception: The stock market has gone up over time; the geophysical crew count has not.

What's going on here? Have we as an industry failed to keep up with competitive demands of the world market and been replaced? Or have we done our jobs too well and glutted the market with our productivity?

The answers I believe are that no, we have not failed to keep up but that the majority of exploration activity is now international, not domestic. And yes, we have had great exploration success in the past, which has reduced the incentives for additional exploration without a significant reduction in finding costs, but developing technology will further decrease finding costs. These decreased finding costs achieved through more efficient operations will support sustained, long-term exploration efforts in a climate of restricted oil price increases.

What then can we expect for the oil exploration industry in the 1990s?

PROSPERING IN THE '90S

Successful exploration service companies in the 1990s will have several characteristics that will enable them to flourish and not just survive. They will be balanced, international companies able to adapt to the business cycles that will inevitably occur within individual exploration areas.

These companies will market integrated services that will provide prospect imaging and interpretation tools for data acquisition and computer processing within land, transition zone, and marine environments. Downhole measurements will be combined with seismic imaging to provide explorationists with estimates of reservoir and rock properties. The successful companies will be adroit in the use of new and emerging technology.

A balanced spread of activity over a worldwide spectrum of business climates and the flexibility to rapidly adapt to changing conditions will be needed to control the boom-bust cycles and to maintain long-term stability. Without such stability the industry will be unable to attract and hold the highly motivated and trained people that are the lifeblood of any industry.

Within the context of the exploration industry, the role of the geophysical contractor has changed.

Rather than just a vendor of standardized acquisition and processing services as defined by the oil and gas exploration companies, the contractors have become the source of technological innovations in both equipment and techniques.

This shift has been driven by a substantial decrease of internal research and development funding by oil companies, by an oversupply of geophysical crews and computing capacity, and by a cost overhang of proved reserves compared with replacement reserves.

TECHNOLOGICAL ADVANCES

The development of 3D seismic is a prime example of the industry's response to new technologies. 3D seismic acquires and processes a volume of subsurface data and provides a map-style view of the geology.

2D seismic acquires and processes vertical slices of subsurface data and provides only a vertical slice view of the geology. Although first introduced in the 1970s, the 3D method was not generally accepted as a useful, albeit expensive, tool until the 1980s.

Within the past several years 3D has grown to include 50-60% of all marine work, and 15-20% of all land work. This rapid growth was stimulated by the success of the method in reducing overall development costs and risks but was made possible by the development of key technologies by service and instrumentation companies.

In both land and marine environments a large number of recording channels is required to achieve the economies of scale that make efficient 3D data acquisition possible. The 3D method emphasizes the areal collection of data. Recording systems with 1,000 channels or more employ digital data telemetry in order to cope with the volume of data. The sheer size of these large 3D crews has meant that efficient crew and data management have become the keys to acquisition profitability.

The continued and rapid growth of computer capacity has enabled our industry to tackle problems and prospects with new computational techniques that would have been uneconomic just a few years ago.

Advances in hardware have been coupled with the creation of efficient software algorithms designed to sharpen our subsurface eyesight. Our ability to image complex subsurface structures has dramatically improved the probabilities of drilling success and has helped to reduce overall risk and cost through the whole cycle of prospect discovery, development, and production lifetime.

The introduction of the interpretation computer workstation has had perhaps the most visible impact on the exploration process. Without this powerful interactive display and analysis tool the explorationist would be severely handicapped in handling the enormous volume of data from a 3D seismic survey. The maturation of these interpretation systems and the high value content of 3D seismic will result in additional demand for 3D surveys over 2D surveys.

EMERGING TECHNOLOGIES

The bulk of our seismic technology development efforts will be focused on how to reduce the overall acquisition, processing, and interpretation costs of 3D surveys.

The use of computers on field crews will continue to grow as "small" computers expand their computational power. Automated, comprehensive quality control of the field data will be mandatory to guard against the potential loss of significant revenue due to downtime on large, capital-intensive field systems.

Data management procedures will be used to ensure the smooth flow of these large data volumes from acquisition through processing. Multicable and multisource systems will continue to grow in size and complexity until system reliability and logistics impose economic limits.

Multisensor seismic systems, 3-component geophones for land, and dual sensor hydrophones and geophones or hydrophones and accelerometers for marine, will gain acceptance only if the substantial additional acquisition and processing costs are justified by results in the form of more-reliable and consistent rock property reservoir estimations.

The introduction of small, inexpensive satellite-based Global Positioning System (GPS) receivers will benefit both land and marine applications by decreasing surveying time and by increasing positioning reliability. The use of differential GPS techniques will provide dynamic 1 m positioning accuracies for marine surface positions and in conjunction with acoustic ranging devices will enable location of all subsurface sources and receivers to better than 5 m accuracy.

This location accuracy is not required for today's seismic imaging methods but may be necessary for tomorrow's high resolution surveys.

A secondary benefit of the use of the GPS system is the availability of a very precise, worldwide, time clock that can be used to time-stamp and synchronize events. The use of common, synchronized clocks is a simple, effective way to tie together several seismic recording systems.

PROCESSING

As the computing power of small and medium sized computers has expanded into the performance range of what used to be considered the domain of a mainframe computer, the industry has sought to develop software that can be run on a variety of machines. Because for most systems the cost of software exceeds the cost of hardware, designers have attempted to construct modular codes that will reduce the long-term costs of software maintenance and increase the longevity of the individual modules.

A trend within the seismic industry is to create software to run under the UNIX operating system, which will allow the programs to run on a mix of platforms. The old software was usually written for a particular operating system and tuned for specific machine hardware.

The trick will be to attain the flexibility of the new and to retain the efficiency of the old.

Most of the seismic imaging methods that are used in 3D processing assume that the subsurface properties are slowly varying and axially symmetric in a plane parallel to the earth's surface. But we have documented evidence that rocks are anisotropic and that some prospects can show a directional variation in seismic velocities of as much as 10%.

These variations can affect the 3D image and perhaps can be used to better characterize the reservoir.

As we increase the spatial sampling density of a 3D survey, we are able to resolve geologic detail with a finer grain, but we pay a penalty in increased acquisition and processing costs. To offset these higher costs our survey strategy has been to trade seismic fold coverage for areal coverage.

For example, a typical dual cable marine crew with a single source can collect two subsurface common depth point (CDP) lines of nominal 60-fold data. That same crew with a dual source can collect four lines of nominal 30-fold data.

Economies of scale will continue to favor the increase in areal coverage at the expense of fold coverage. We will have to learn how to do a better job of acquisition quality control and process imaging in order to make better use of this low fold data.

INTERPRETATION

As workstations and software become more capable we will be able to perform more complex seismic analyses that reach down closer to the raw data. The explorationist will be able to do interpretive processing on a larger portion of his prospect and accomplish the task in a manner that will not be intrusive to the flow of the interpretation process.

The workstation will be the focus of efforts to integrate seismic reflection data with geophysical data such as vertical seismic profiles (VSP), well log, and other reservoir data into a coherent database that can be directly input into supercomputer models used to predict fluid content and fluid flow within the reservoir.

The fortunes of the geophysical industry depend heavily on the timely introduction and intelligent use of technology. We must learn how to manage the new technologies in order to compete with other economic sectors for capital and talent. This effort requires a long-term commitment to programs of professional training and job enrichment, quality management, and R&D investment.