What's new in exploration

Once, I was a volunteer science teacher in a Houston-area private school. I taught biology students this line—every molecule in your body, including those controlling your DNA, unless it arrived recently from outer space, came from a very old, earth-based rock. That rock likely was derived from an earlier rock, and so on. Therefore, you really are billions of years old, no matter how nature has reassembled you to look the way that you do today.

I would tell chemistry students that the rocks, therefore, are collections of minerals that are molecular and sometimes crystalline in nature; they can be predicted, measured and reduced further to create alternate compounds or minerals. Such class torture would include Stoichiometry and Darcy to point out that molecules are constantly in motion [disequilibrium] and changing form, requiring an understanding of mass balance and/or conservation of mass.

I would instruct physics students that the DNA molecule, formed from a garden variety of atoms, was nothing more than a highly ordered assembly, also of constantly moving particles, whereby all of nature was subject to the energy laws of physics. Further, those laws, operating inside the atoms, making the molecules, assembled as your DNA, determined if you would be a camel or a human. All those DNA molecules, all identical within you, determined what part of you became a brain, a foot or a backside part.

Oil is also very dynamic—always changing, always moving. Hydrocarbons change physical and chemical states constantly, back and forth, over time, temperature and pressure. While reservoir tests, worldwide, showed no liquid oil is more than 1 million years old in its current state, that does not mean those molecules are that young. Common belief among some geo’s, accountants in senior management, and people who watch Jurassic World, is that today’s oil is from dinosaurs, or at least the plants that the creatures ate. Where did the molecules come from for the plants, and where did all that CO₂ come from to feed the plants? Where are those molecules now? Some are in the keyboard below my fingers. A few billion escaped into outer space, but most stayed on, or near, the planet.

What’s new in exploration? The focus has changed slightly from using seismic data seeking buried mountain ranges with anticlinal traps, and from mapping Peter Vail-stratigraphic traps with accumulations of gas that show AVO, to searching for ancient burial grounds of those early collections of detritus, organic ooze and swampy reductions that nowhere show up as amplitude on seismic.

Hydrocarbon generation naturally results from maturation of buried organic matter. Organic matter (organic carbon) in sediments underlying the oceans is derived from different sources (Emeis and Kvenvolden, 1986), including marine phytoplankton, Phytobentos in shallow water with sufficient light, Bacteria, and Allochtonous (i.e., land derived) material. Organic matter undergoes changes in composition with increasing burial depth and temperature. The three steps in the transformation of organic matter to petroleum hydrocarbons are diagenesis, catagenesis and metagenesis. Petroleum hydrocarbons exist as gaseous, liquid and solid phases, depending on temperature, pressure, burial time, and system composition. http://www-odp.tamu.edu/publications/tnotes/tn30/tn30_2.htm

The industry has focused on, and made some effort at finding, those molecular-sized, semi-mobile accumulations of hydrocarbons, still called late-stage kerogens, that remain in some collectable physical state. And not just in Western Canada. Exploration teams that I have talked to have looked in Eastern Canada as a north extension to the U.S. Appalachians, as well as Poland, Kazakhstan, Patagonia, West China, West Namibia, South Africa, and yes, Illinois. None of these places are seismic attribute-friendly. All were chased by old fashioned basin and range geology.

Follow this geologic description from Australia. Look at the detail and the emphasis they place on generation: http://www.pir.sa.gov.au/__data/assets/pdf_file/0005/58226/pgsa_vol2_2nd_10.pdf. I also point to the many Journal of Petroleum Geology papers on source rock and generation: http://www.academicconcepts.net/concepts/423/hydrocarbon_generation.htm.

One has to conclude, that nature is not much better than engineers in flowing all the liquid organics out of a rock, especially over a normal 8-12-year field life. Given our appetite as consumers, perhaps that is intentional. Most of our oil and gas is still in the ground for future generations of explorationists to find and extract. Sorry King Hubbert.

Some leading groups in the O&G community have rediscovered thinking at the molecular level of exploration and are looking for “old” hydrocarbons in any physical state. This process may become their new exploration frontier. The study of reservoir dynamics and fluid flow within a rock is changing in definition [i.e. shale oil]. That means micro- to nano-geochemistry will be reborn, maybe paleontology. Certainly, micro-paleontology needs a boost, as does creation of newer applications of electromagnetic and resistivity technologies, surface and borehole.

The truth is that over the last 40 years, a great deal of reservoir work, and almost all shale oil work, has taken place without the benefit of seismic and the fervor of amplitude analysis. I have been in the offices of several production companies, where there were no geos, no workstations, and no seismic data. What does that mean?  

About the Authors

William (Bill) Head

Contributing Editor

William (Bill) Head is a technologist with over 40 years of experience in U.S. and international exploration.