Lixia Zhang
Tongwei Zhang
Paul C. Hackley
2017
<p><span>An organic petrology evaluation and a determination of solid bitumen reflectance </span><span class="equationTd inline-formula"><span id="MathJax-Element-1-Frame" class="MathJax" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mrow><msub><mi>BR</mi><mi mathvariant="normal">o</mi></msub></mrow></math>"><span id="MathJax-Span-1" class="math"><span><span id="MathJax-Span-2" class="mrow"><span id="MathJax-Span-3" class="mrow"><span id="MathJax-Span-4" class="msub"><strong><span id="MathJax-Span-5" class="mi">BR</span></strong><sub><span id="MathJax-Span-6" class="mi">o</span></sub></span></span></span></span></span></span></span><span> were completed for organic-rich Triassic Yanchang Formation mudrocks (</span><span class="equationTd inline-formula"><span id="MathJax-Element-2-Frame" class="MathJax" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mrow><mi>n</mi><mo>=</mo><mn>15</mn></mrow></math>"><span id="MathJax-Span-7" class="math"><span><span id="MathJax-Span-8" class="mrow"><span id="MathJax-Span-9" class="mrow"><i><span id="MathJax-Span-10" class="mi">n</span></i><span id="MathJax-Span-11" class="mo">=</span><span id="MathJax-Span-12" class="mn">15</span></span></span></span></span></span></span><span>) from the Ordos Basin, north-central China, as part of a larger investigation of “shale gas” resources. These data were integrated with information from Rock-Eval programmed pyrolysis to show that the samples are in the peak oil window of thermal maturity and that organic matter is dominated by solid bitumen with minor amounts of type III kerogen (vitrinite and inertinite) from vascular land plants. Describing a “kerogen type” for these rocks based strictly on parameters determined from programmed pyrolysis is misleading because the original organic matter has converted to hydrocarbons (present as solid bitumen), a large proportion of which may have been expelled into adjacent reservoir facies. However, based on the comparison with immature-early mature lacustrine mudrock (Garden Gulch Member of Green River Formation) and marine shale (Boquillas Formation), we suggest that the original organic matter in the organic-rich samples examined for our study may have been type I/II kerogen with hydrogen index values of </span><span class="equationTd inline-formula"><span id="MathJax-Element-3-Frame" class="MathJax" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mrow><mo form="prefix">&gt;</mo><mn>700</mn><mtext>&#x2009;&#x2009;</mtext><mi>mg</mi><mtext>&#x2009;</mtext><mi>HC</mi><mo>/</mo><mi mathvariant="normal">g</mi></mrow></math>"><span id="MathJax-Span-13" class="math"><span><span id="MathJax-Span-14" class="mrow"><span id="MathJax-Span-15" class="mrow"><span id="MathJax-Span-16" class="mo">></span><span id="MathJax-Span-17" class="mn">700</span><span id="MathJax-Span-18" class="mtext"> </span><span id="MathJax-Span-19" class="mi">mg</span><span id="MathJax-Span-20" class="mtext"> </span><span id="MathJax-Span-21" class="mi">HC</span><span id="MathJax-Span-22" class="mo">/</span><span id="MathJax-Span-23" class="mi">g</span></span></span></span></span></span></span><span> TOC.</span></p>
application/pdf
10.1190/INT-2016-0111.1
en
Society of Exploration Geophysicists
Organic petrology of peak oil maturity Triassic Yanchang Formation lacustrine mudrocks, Ordos Basin, China
article