applications

Continuing the search for oil by SIMON GRAY

T he use of computers for data pro- cessing in the oil exploration in-

dustry has changed dramatical- ly, not in the areas of application but in the extent to which the industry de-

pends upon computers within these fields. The huge volu.me of informa-

tion now being processed has resulted in a wide range of advanced seismic

and geophysical software packages and the emergence of the 32 bit ‘super-

minis’ which offer the power of main-

frame systems, required both for pro- cessing and to run the increasingly sophisticated peripherals, at the cost

levels of the minicomputer. By the early seventies all the obvious

oil fields had been found and it was

becoming increasingly difficult to find

gas and oil to keep pace with demand. This resulted in a tremendous upsurge of activity in the mid-seventies for field

data acquisition. But as the risks and costs involved in oil and gas explora-

Abstract: Geophysical evaluation has assumedgreat importance within the oil industry as oil exploration has become more costly and risky. The needfor efficient seismic data collection andsophrsticated onsite data analysis with fast response tzmes has led to th use of 32 bit minis. Manv consultancies supplying the oil industry now offer complete systems with modular data processing packages, image processrng and the latest hardware incorporating interactive colour graphics.

Keywords: data processing, seismology, geophysical measurement.

Simon Gray is a technical journalist

tion increased, so the demand for geophysical evaluation soared, a situa- tion which is expected to continue well

into the next century. The industry has thus found itself in transition from

a period dominated by reconnaissance activities to one that requires a cech-

nology which can provide three dimensional subsurface imaging and

adequately support the increased activity in this field. By taking a closer

look at the trends in the industry it is

possible to gain a better understanding of what was, and is, required in terms of processing power.

Seismic data collection

Original sites for oil exploration were selected from an observation of

structural features largely by the use of aerial survey and primitive seismic

survey. Twenty years ago it was not

possible to locate accurately any strata

below the surface. Seismic survey op- erations now play a far more significant part in the discovery and exploitation of oil resources both on land and be-

neath the sea as geophysicists seek to map the subsurface of the earth.

Seismic data is collected by sensors, either trawled from ships at sea or

placed on land, which measure the velocities of sound waves resulting

from controlled explosions. The seis- mic data is digitized to magnetic tape for computer processing and plotting. The resulting plot shows a seismic pro- file of the rock layers below the sea bottom or ground, which reveals faults

and other structural geophysical in-

formation from which geophysicists can detect the most favourable loca- tions for oil deposits.

Seismic data csollection techniques

and technology have advanced con- siderably over the past few years. The

need for greater fid.elity of information has resulted in twice the number of

surface collection points, and sam- pling rates have increased. Each shock

generates a huge amount of data for

collection. The Vibroseis system, for example, translates up to 8Mbyte of data per shock. A typical seismic sur-

vey, therefore, now requires the pro- cessing of approximately eight times more data than before, with vast num-

bers of crunching routines

Data analysis

After collection the data goes to spe-

cialist consultancies for post-seismic interpretation. Modern seismic pro-

cessing uses computers for a variety of data-reduction, modelling and display

techniques, to analyse and translate the digital field data, together with a wide range of advanced and special-

ized software from computer consul- tancies. The raw mformation can be

used to provide analysis in seismic and stratigrphic processing, as well as

wavelet processing, modelling and vertical seismic profiling.

Sophisticated and highly efficient database systems such as the Geo- Graphics Interpretation Data Base and Mapping System Iflrom Scott Pickford and Associates, mean that a wide vari-

~0125 no 3 april 1983 0011-684X/83/030021-02$03.00 @ 1983 Butter-worth &Co (Publishers) Ltd. 21

ety of well, map, seismic and general developed to run on Gould SEL corn- included 16 bit CPUs and integral geographical data can be retrieved and puters and Britoil has ordered a 32/87 array processors. correlated with the new data. to run the package. Operations co- At that time, DPC realised that they

vered by the Megaseis system include needed a more powerful CPU than

Complete seismic data seismic processing functions such as their existing 16 bit system. Specifical-

processing packages velocity analysis, predictive convolu- ly its requirement was for a CPU with a tion and complex trace analysis, very fast input/output system and high

Historically, data acquisition and the together with modelling and inter- computational capability. They also interpreted display were two totally pretation, navigation and mapping, needed a CPU that could accommo- separate areas but the enormous ad- and interactive colour graphics. date controllers working in a standa- vances in the computer techniques em-

Remote sensing via satellites lone mode to do tape to tape, tape to ployed have blurred the line between disc and disc to disc transfers without the two functions. Increasingly there- fore, the interpretation specialists are

offering complete seismic data proces- sing systems composed of the latest

hardware to run their own software. Seismic processing, however, de-

mands all the processing power that can be made available to handle the

vast amounts of data.

Traditionally the processing has been a job for the mainframe computer

but these are costly. In addition, the expense of having data acquisition crews onsite has led to a growing de- mand for onsite processing to achieve a

faster response, and here again the

mainframe is unsuitable. Increasingly computer consultancies have looked to the 32 bit superminis as the best

machines for their purposes, both in

terms of processing power and cost. The heavy number crunching applica-

tions can exploit fully the power of the

32 bit machines, particularly those ranges which, as in the case of the Gould SEL range offer powerful cache memory and floating point firmware to

give exceptionally fast and efficient operating speeds while still supporting

high speed input and output opera-

tions . Seiscom Delta United, system spe-

cialists to the oil industry, is offering a new generation of its Megaseis family of geophysical data processing sys- tems. This system is a very powerful complete modular data processing package specifically designed for geophysical applications, composed of the latest state-of-the-art hardware, highly sophisticated software and complete user support. Megaseis was

An increasingly large percentage of data now comes from remote sensing, that is, the use of images in various

parts of the electromagnetic spectrum acquired from satellites to produce pictures enhanced through digital

techniques. These remote sensing

techniques represent an extremely cost effective and rapid method of acquir-

ing unique information. The effect is

to create large archives of remote sensed imagery from satellites such as Landsat. From the processed imagery it is possible to obtain maps to

1: 100 000 scales of land surfaces, otherwise unobtainable because the

region is inaccessible, as well as shal- low sea-bed mapping to a depth of 30 metres.

Gould itself offers a powerful image

processing system comprising the Concept 32 range linked by a 32 bit

high speed data hardware and software interface to a Gould DeAnza II’8500

image array processor. The Gould DeAnza library of image processing software, LIPS, provides high per-

formance tools to accommodate a wide range of image processing applica- tions.

Superminis in use

In 1979 the Denver Processing Center Inc (DPC), a large independent sup- plier of data seismic processing sys- tems decided to expand its business by selling complete turnkey systems which included proprietary software developed by DPC as well as some specially designed interfaces and con- trollers. When this decision was made, DPC was using seven systems which

CPU intervention. Finally they needed a CPU that could be connected

to a vector processor. They installed a 32/77, Gould SEL’s then current top

end 32 bit system. In 1981, when looking at the even

greater projected seismic processing requirements of the eighties, DPC de-

cided it needed even more power and a more efficient way to connect the vec-

tor processor to the CPU. The com- pany became Gould SEL’s first cus- tomer for the new 32187, which offers

six times the power of the 32177, with ECL technology to provide a proces- sing speed of 3.6 MIPS and common

memory interface for the vector pro- cessing unit, as well as protecting

DPC’s large software investment.

Future industry developments

The future pattern for the remainder of the eighties will be software special-

ists and hardware manufacturers keep- ing pace one with another in maintain- ing their commitment to the industry.

For the time being at least, the main areas for enhancements are likely to be directed towards the provision of even

more sophisticated graphics terminals and plotters, such as the Seischrome II

laser plotter, since better displays pro- duce better interpretation. With the increasing costs of image processing there is also a concentration upon simultaneous data acquisition and pre- processing and more fully interactive interpretation in general. Whatever the future holds, an oil industry with- out increasingly sophisticated compu- ter systems is inconceivable. cl

22 data processing