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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 65 (1981)

Issue: 7. (July)

First Page: 1364

Last Page: 1364

Title: No Title Provided: ABSTRACT

Author(s): R. P. Von Herzen, J. A. Helwig


The drilling of deep wells on the continental margins provides a means to augment the relatively sparse heat-flow data in this geologic province. For this purpose we have analyzed data from the COST B-2 well in the Baltimore Canyon basin off New Jersey. Although the temperature gradient to nearly 5 km depth is relatively well determined from successive bottom hole temperature measurements at several depths in this hole, very few cores suitable for the determination of thermal conductivity (K) were taken. We have determined K for various lithologies from transient needle-probe measurements on selected samples of drill cuttings. The appropriately average in-situ conductivity (K), over the depth intervals between temperature measurements, is estimated by using lithology and orosity determinations over the drilled section.

The correlation of K with grain size of clastic sediments is probably related to quartz content. A relatively large uncertainty in the estimated value for limestone produced only a small uncertainty in heat flow. Shale K values show a significant decrease below 3,350 m depth.

Comparison of K with laboratory results shows the large effect of in-situ porosity and temperature. The uppermost estimate of Q (1.30 HFU at 1,220 to 3,068 m) may be low owing to unrealistically low estimate of K; the reason for an even lower estimate of Q (0.78 HFU) deeper than 4 km is uncertain. The most consistent and reliable values (1.26 to 1.30 HFU) are for the depth interval between 1,220 and 4,104 m. The implications of these measurements for the maturation of hydrocarbons on passive margins will be mentioned.

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