Geology topics

I.R. Kaplan

Publications and source records attributed to I.R. Kaplan.

3 recordsLinked to original sources

USGS2004

Thermal alteration of Cretaceous black shale from the Eastern Atlantic. III: Laboratory simulations

Laboratory thermal alteration (pyrolysis) experiments were carried out on composited Cretaceous black shale samples from DSDP Hole 368. Dried rock samples (low water-rock ratio) were heated in an inert atmosphere in the range of 250–500°C and the resultant bitumen and kerogen concentrates were characterized. Pyrobitumen forms initially (250°C), then major hydrocarbon generation occurs from 300–360°C and oxygenated products ( e.g. alkanoic acids) have a maximum yield at 330–360°C with minor generation to 500°C. Dealkylation of the aromatic hydrocarbons to the parent polynuclear aromatic hydrocarbons occurs above 400°C. The kerogens become more aromatic with increasing pyrolysis temperature (atomic H/C decreases from 1.2 to 0.5 and vitrinite reflectance increases to 3%). The temperature ranges of pyrobitumen, bitumen, and PAH formation in dry pyrolysis experiments are of utility in correlating with field data on ore genesis.

Atlantic Ocean, Cape Verde Rise↗

USGS2003

Insights into oil cracking based on laboratory experiments

The objectives of this pyrolysis investigation were to determine changes in (1) oil composition, (2) gas composition and (3) gas carbon isotope ratios and to compare these results with hydrocarbons in reservoirs. Laboratory cracking of a saturate-rich Devonian oil by confined, dry pyrolysis was performed at T = 350-450??C, P = 650 bars and times ranging from 24 h to 33 days. Increasing thermal stress results in the C15+ hydrocarbon fraction cracking to form C6-14 and C1-5 hydrocarbons and pyrobitumen. The C6-14 fraction continues to crack to C 1-5 gases plus pyrobitumen at higher temperatures and prolonged heating time and the ?? 13Cethane-?? 13Cpropane difference becomes greater as oil cracking progresses. There is considerable overlap in product generation and product cracking. Oil cracking products accumulate either because the rate of generation of any product is greater than the rate of removal by cracking of that product or because the product is a stable end member under the experimental conditions. Oil cracking products decrease when the amount of product generated from a reactant is less than the amount of product cracked. If pyrolysis gas compositions are representative of gases generated from oil cracking in nature, then understanding the processes that alter natural gas composition is critical. ?? 2003 Elsevier Ltd. All rights reserved.

Organic Geochemistry↗

USGS1988

Composition and stable-isotope geochemistry of natural gases from Kansas, Midcontinent, U.S.A.

More than 28??1012 ft.3 (79??1010 m3) of natural gas and 5.3??109 bbl (8.4??108 m3) of oil have been produced in Kansas, U.S.A., from Paleozoic carbonate and sandstone reservoirs on structural uplifts and shallow embayments along the northern margin of the Anadarko basin. A heavily-explored, geologically well-characterized state, Kansas is an excellent place to study hydrocarbon migration and to test geochemical models for the origin of natural gases. Immature to marginally-mature rocks of eastern Kansas (Cherokee and Forest City basins) produce mixed microbial and thermogenic gases. Gases in this region have wetness = 0.03-51%, methane ??13C = -65 to -43??? and methane ??D = -260 to -150???. Gases from central and western Kansas (Nemaha uplift to Hugoton embayment) are entirely thermogenic and have wetness =4-51%, methane ??13C = -48 to -39??? and methane ??D = -195 to -140???. Ethane and propane ??13C-values throughout Kansas vary from -38 to -28??? and from -35 to -24???, respectively. Mature thermogenic gas (generated from source rocks in southwestern Kansas and the Anadarko basin with 1.0% ??? Ro ??? 1.4%) is recognized throughout the state. Lateral migration into shallow reservoirs on the Central Kansas and northern Nemaha uplifts and in the Cherokee basin probably occurred along basal Pennsylvanian conglomerates and weathered Lower Paleozoic carbonates at the regional sub-Pennsylvanian unconformity. Early thermogenic gas (generated by local source rocks with Ro ??? 0.7%) is recognized in isolated fields in the Salina and Forest City basins, in Ordovician reservoirs beneath the sub-Pennsylvanian unconformity in the Cherokee basin, and in reservoirs generally above the unconformity in the Cherokee and Sedgwick basins, the eastern Central Kansas uplift and the Hugoton embayment. ?? 1988.

Chemical Geology↗