Technology Focus: Formation Evaluation (August 2014)
- Bob Harrison (Consultant Petroleum Engineer)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- August 2014
- Document Type
- Journal Paper
- 70 - 70
- 2014. Copyright is retained by the author. This document is distributed by SPE with the permission of the author. Contact the author for permission to use material from this document.
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Any oil and gas deal, whether it is acquisition, divestment, greenfield, brownfield, or out of left field, usually involves a data room, where rich seams of proprietary information can be mined for a limited period. However, this physical data room, as opposed to a virtual version where data are downloadable, is the bane of due diligence.
Some may recall caffeine-fueled assignments to paw through boxes brimming with confidential documents that allegedly held the financial secrets of a potential acquisition. The process is expensive; can be a logistical nightmare of travel arrangements, visas, and inoculations; and is always stressful because of time pressure. Data rooms are migraine inducing.
The priority of the petrophysicist on a data-room team is to access digital data for all wells—for example, logs, wireline formation pressures, and deviation surveys for depth conversion. Often neglected are the log headers themselves, which provide data on tool setup, bottomhole temperature, mud properties, and the casing program and present the logging engineer’s comments. Gathering data is less straightforward if they are in an unfamiliar language or are vintage (noncombinable tools with unfocused measurements requiring more runs). These factors require translation, tool response modeling, and increased depth matching, adding time, cost, and potential for error.
Petrophysicists audit the hydrocarbons in place by reviewing previous studies to confirm the all-important trinity of porosity, water saturation, and net pay claimed by the seller. The appropriateness of the saturation-height function in the geomodel is checked for the assumed hydrocarbon and rock type, or merely to ascertain that one was used at all. Proposed fluid contacts must be verified, no mean feat when faced with structure maps showing only oil-down-to (ODT) and water-up-to (WUT) depths, with the contact possibly being anywhere in between. Some companies assume that the fluid contact is halfway between ODT and WUT, which is a completely arbitrary approach.
In these digital days, almost everything needed to carry out petrophysical due diligence can be downloaded for off-site analysis. However, there are places where it is illegal to take data out of the country, so physical-data-room attendance is compulsory. In these instances, as in the past, the petrophysicist’s briefcase might hold color pencils, a ruler, tracing paper, chart books, and maybe a planimeter, a strange device for measuring areas within mapped contours. Yet painful memories suggest that the most important piece of equipment one should take along to a data room is probably a bottle of aspirin. JPT
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