Computers & Geosciences Vol. 13, No. 4, pp. 439--440, 1987 0098-3004/87 $3.00 + 0.00 Printed in Great Britain. All rights reserved Copyright © 1987 Pergamon Journals Ltd

CONFERENCE REPORT

C O M P U T E R S & I N S T R U M E N T A T I O N IN G E O L O G Y

A. D. M. BURWELL* British Petroleum Research Centre, Exploration & Production Division, Chertsey Road,

Sunbury-on-Thames, Middlesex TWl6 7LN, U.K.

Report of a meeting held by the Geological Information Group at the Department of Geology, University of Aberdeen, 21st November 1985

About 85 geologists and computer scientists attended this meeting concerned with use of computers to con- trol, monitor, and process data from instruments used in geological and geophysical exploration and analyti- cal work. In addition to the nine papers presented, there were nine demonstrations of exploration-related use of computers for procedures such as gridding and contouring, thermal modeling and composite log dis- play.

The morning session, chaired by G. Baxter, was devoted to the acquistion and processing of downhole data. In a keynote address, P. Lloyd of Schlumberger described a powerful new logging tool for electrical imaging of reservoir sections. This tool, an adaptation of a dipmeter, provides 30--40% coverage of a bore- hole wall and generates a signal which may be processed into a 16-level white-grey-black image. The image, reflecting contrasts in resistivity, provides a 1/5 scale representation of the borehole wall which, in both porous and tight environments, frequently com- pares favorably with recovered cores. Future applica- tions of the new tool will be identification and charac- terization of fractures, study of porosity and per- meability barriers (e.g. stylolites) in carbonates, and detailed textural analysis of siliciclastics (e.g. shaly laminations in sandstones).

T. Dickinson described the GEODATANET sys- tem, currently under development by Gearhart Geodata Services, which manages and processes a wide range of data acquired during drilling. Data may be collected for up to 1000 downhole attributes. Some data are acquired automatically (e.g. drill bit weight, mud weights in/out, data from logging runs) whilst other data are acquired and input to the system manu- ally (e.g. analysis of cuttings). PDP minicomputers are used for data acquisition and storage and for subsequent data processing and display. Several dis- play applications are available, for example data may be displayed during acquisition or may be displayed in composite log form once collection is complete. The aims of this system are to assist in control of

*Present address: BP Exploration Co. pie, Britannic House, Moor Lane, London EC2Y 9BU, U.K.

drilling operations, to systematize data collection, and to improve rig-site decision making.

In a second contribution from Schlumberger, P. Delfiner described two systems, currently under development, for interpreting wireline log data in terms of lithology (LITHO) and sedimentary struc- tures (SYNDIP). The LITHO system uses data from a wide range of logs: initially, a preprocessing system uses data (e.g. from SP and resistivity logs) to mini- mize variations in other logs (e.g. neutron, sonic) which are of nonlithological origin. Corrected log data then are analyzed by computer in terms of multi- dimensional log-data space to derive a lithological- mineralogical identification, Bayesian logic being used in decision making. External knowledge may be used to limit decisions. The SYNDIP program uses microresistivity data to determine structural heteroge- neity in strata. Applications include determination of net pay in reservoirs and analysis of textural fabric.

The first afternoon session, also chaired by G. Baxter, was devoted to control of geochemical instru- ments and acquisition and processing of data from these instruments. J . Gray of the British Petroleum Research Centre described the computer-based sys- tem used by BP in their organic geochemistry labora- tories. The system is built around a Hewlett-Packard 1000 computer which runs a laboratory automation subsystem (LAS). Instruments are controlled in a variety of ways including event control modules (for autosamplers), serial links to intelligent instruments, and satellite microprocessors. The LAS acquires data via current loops connected to A/D converters which sample instrumental data at between 0.5 and 16 Hz. Software running on the HP 1000 is used to generate geochemical parameters from raw data and to create graphical output. In future, the computer system is to be enhanced to allow automatic transfer of data from the analytical system to an existing VAX-based, geochemical database.

M. Sauer described methods used by Poroperm Geochem in the processing of gas chromatographic data and in maturation modeling. A ZS0-based Trivector microcomputer, interfaced to a gas chro- matograph, is used for collection, graphical display

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and manipulation of data from oil samples. Graphical manipulation functions include scale expansion (to resolve low molecular weight hydrocarbons), back-to- back comparison of data from separate oils, and baseline corrections in quantitative analysis. The mat- uration modeling program, which runs on a micro- computer, generates age-depth plots which show sub- sidence curves for stratigraphical units. Using an ass- umed thermal gradient, color-coded areas corre- sponding to a range of values for hydrocarbon matur- ity index may be superimposed on a plot. Thus, it is possible to determine which units in a sequence have gas- or oil-bearing potential.

W. Perkins (coauthor C. Topley) described work in progress at Oxford Polytechnic: A BBC microcom- puter, interfaced to a Perkin-Elmer 5000 atomic ab- sorption spectrophotometer (AAS), is used for instru- mental control and for collection, processing and dis- play of data. In one analytical run, up to 6 (from a choice of 13) elements may be determined automatic- ally in up to 50 samples. Microcomputer-based analy- tical parameter data (e.g. oxidant-fuel ratio, stan- dards used), modifiable by the operator, are trans- ferred to memory in the AAS and used by the AAS in a semiautomatic set-up procedure. At various stages during setup, a program on the BBC micro prompts the user to take action (e.g. insert lamps, load sam- ples). Once initiated, analysis is automatic, the results (absorbance or concentration) being stored on disk or optionally displayed graphically (e.g. calibation cur- ves).

The final session, chaired by R. Howarth, consis- ted of one paper on paleontological data manipula- tion and two on field-based use of microcomputers in geophysics. During presentation of the first of these papers, B. Wells demonstrated how biostratigraphers at Robertson Research use a touch screen on a Hew- iett-Packard 150 microcomputer to enter palaeon- toiogical data. Whilst working on a slide, a biostrati- grapher touches one of up to 240 fossil names display- ed on a screen to signify the corresponding fossil's presence. Optional abundance data may be entered (again using the touch screen). A biostratigrapher may work with one of a number of standard fossil name lists constructed for different time zones, areas and micropaleontology disciplines. Input data may be

edited via conventional form-based screens or may be output on hard copies (e.g. matrix occurrence charts).

W. Sowerbutts of Manchester University provided a review of applications of microcomputers in field- based geophysics. Many modern geophysical instru- ments have solid state memories for storing survey data, keyboards for inputting associated (e.g. posi- tional) information, and serial links for off-loading data to computer. If data are to be processed/display- ed in the field, appropriate computer systems are either rugged desk-top (e.g. Apple II) or hand-held (e.g. Husky) micros linked to battery-powered periph- erals. Sowerbutts described a system, developed at Manchester, consisting of a magnetic radiometer and an ultrasonic receiver (for position fixing) both feed- ing via A/D converters into an Apple microcomputer. Data are processed and displayed in the field as con- tour maps or isometrics. Current developments in- clude computer-control of instruments and high fre- quency transfer of data using direct memory access techniques.

I. Hill of the University of Leicester described field-based use of a BBC microcomputer for process- ing and displaying digital, engineering seismic data from a Bison seismograph. The microcomputer uses a second processor and double-density disks to store SEGY format data; memory partitioning (data- programs) and program chaining are used. The sys- tem has been used successfully for conventional seis- mic refraction work; t-X and multiple planar/ irregular layer plots may be produced. A seismic re- flection processing/display system is being developed: velocity analysis, move-out corrections and constant offset corrections may be undertaken; trace sorting and trace stacking are yet to be addressed. The aim is to produce a reflection processing system, reliable in all geological environments, which can be used to provide guidance on the positioning of seismic lines.

This well-attended meeting addressed all aspects of computers and instrumentation from instrument con- trol, through data collection and processing, to data display. There was an unusually wide range of demonstrations covering many facets of exploration data processing. Thanks are due to the two chairmen, the speakers, and to the University of Aberdeen for providing a most satisfactory venue.