Richard W. Crawford

Biological markers from Green River kerogen decomposition

Abstract Isoprenoid and other carbon skeletons that are formed in living organisms and preserved essentially intact in ancient sediments are often called biological markers. The purpose of this paper is to develop improved methods of using isoprenoid hydrocarbons to relate petroleum or shale oil to its source rock. It is demonstrated that most, but not all, of the isoprenoid hydrocarbon structures are chemically bonded in kerogen (or to minerals) in Green River oil shale. The rate constant for thermally producing isoprenoid, cyclic, and aromatic hydrocarbons is substantially greater than for the bulk of shale oil. This may be related to the substantial quantity of CO 2 which is evolved coincident with the isoprenoid hydrocarbons but prior to substantial oil evolution. Although formation of isoprenoid alkenes is enhanced by rapid heating and high pyrolysis temperatures, the ratio of isoprenoid alkenes plus alkanes to normal alkenes plus alkanes is independent of heating rate. High-temperature laboratory pyrolysis experiments can thus be used to predict the distribution of aliphatic hydrocarbons in low temperature processes such as in situ shale oil production and perhaps petroleum formation. Finally, we demonstrate that significant variation in biological marker ratios occurs as a function of stratigraphy in the Green River formation. This information, combined with methods for measuring process yield from oil composition, enables one to relate time-dependent processing conditions to the corresponding time-dependent oil yield in a vertical modified- in situ retort even if there is a substantial and previously undetermined delay in drainage of shale oil from the retort.

Development of a totally computer-controlled triple quadrupole mass spectrometer system

A totally computer‐controlled triple quadrupole mass spectrometer (TQMS) is described. It has a number of unique features not available on current commercial instruments, including: complete computer control of source and all ion axial potentials; use of dual computers for data acquisition and data processing; and capability for self‐adaptive control of experiments. Furthermore, it has been possible to produce this instrument at a cost significantly below that of commercial instruments. This triple quadrupole mass spectrometer has been constructed using components commercially available from several different manufacturers. The source is a standard Hewlett‐Packard 5985B GC/MS source. The two quadrupole analyzers and the quadrupole CAD region contain Balzers QMA 150 rods with Balzers QMG 511 rf controllers for the analyzers and a Balzers QHS‐511 controller for the CAD region. The pulsed‐positive‐ion‐negative‐ion‐chemical ionization (PPINICI) detector is made by Finnigan Corporation. The mechanical and elec...

Real-time, on-line determination of carbon monoxide using charge exchange with krypton in a triple quadrupole mass spectrometer

A triple quadrupole mass spectrometer (TQMS) is used as an on-line analyzer for pyrolysis products from oil shale, tar sands, and coal. Besides determining many hydrocarbon as well as 10 sulfur-containing species, it is important to determine the major oxygen-containing products: H/sub 2/O, CO/sub 2/, CO, and COS. CO is a particular challenge. It is impractical to remove the ubiquitous contribution of hydrocarbons to the ion at m/z 28 when using the normal MS mode and the product fragment at m/z in 16 MS/MS mode is unsatisfactory. With the replacement of Ar with Kr as the collision gas in the TQMS, a charge transfer reaction takes place with the CO/sup +/ ion but not hydrocarbon fragment ions of mass 28. By use of MS/MS mode with m/z 28 precursors, the major isotope of Kr at m/z 84 was monitored; this charge exchange product was linearly proportional to CO/sup +/.

Automatic Apparatus for the Determination of Helium Diffusion in Solids

An apparatus has been designed and built to determine automatically the rate of release of helium from various solids as a function of temperature. The diffusion of He in single crystals of neutron irradiated LiH is used to describe the operation of the apparatus. Samples can be maintained in a vacuum or in an automatically maintained gas (other than noble gas) atmosphere and held at temperatures from 200 to 1400°C. Helium evolved from the sample is periodically removed. A quantitative determination and standardization for He are automatically performed. If a gas atmosphere is used, this is removed from the helium by use of a titanium sublimation pump. The He which remains is then measured with a low resolution high sensitivity residual gas analyzer (partial pressure gauge). The system is capable of measuring at least 10−10 cm3 STP helium.

Gas Chromatography/Mass Spectroscopy/Infrared (GC/MS/IR) Analysis Using A SCOT GC Column, A Quadrupole MS, And A Fourier Transform Infrared Spectrometer (FTIR)

A GC/MS has been interfaced to an FT-IR so that real time MS and IR spectra are recorded on the identical sample. After much effort at optimizing the match between the GC and the IR, it was found that a nearly optimum trade-off between resolution and sensitivity was obtained using a SCOT column. To preserve the CC resolution, a makeup gas flow was used with a standard light pipe to optimize flow rates and conditions in the FT-IR. Further steps in this optimization include small sized detectors and matched light pipes which are currently being prepared. The GC/MS and GC/IR are coupled in parallel by a constriction splitter operating in Mach limited flow, with about 90% of the sample going to the infrared system. Initially, the computer library search outputs of both systems were integrated manually, but the output from the separate HP21MX (GC/MS) and Nova 3 (FT-IR) mainframes is being gradually integrated for combined data processing. Further integration of GC retention times into the qualitative interpretation is being planned. The ternary GC/MS/IR hyphenated instrument has shown the following advantages over its binary ancestors: (1) Added resolvability of overlapping peaks, particularly those involving isomers. (2) Simpler end searches by comparing the hit lists from the IR and MS spectral searches. (3) Complementary structural information on samples where library searches were unsuccessful.