Horizontal Drilling Gives New Life to an Old Oil Play

Editor’s Note: This is the last article in our Tuesday series ‘Unconventional Oil Exploration’

This is our sixth and final article in a series of posts on oil and gas exploration and production of unconventional oil resources, which are classified as such due to the novel technologies required to extract them. Tight oil is unconventional oil found in low permeability shale and sedimentary rock formations. Tight oil deposits were once considered technically unrecoverable, being too complex and expensive, if not impossible, to access, but thanks to advances in horizontal drilling and multistage hydraulic fracturing (fracking) technology, tight oil is now being extracted at a rapid rate.

As explained in Unconventional Oil Exploration, Part 4: Tight Oil,companies may drill for tight oil at an established site when the conventional, easily-accessible oil starts to taper off but data indicates the presence of tight oil. A prominent example of this is the Permian Basin, a more than 100 year-old oil field located in West Texas and southeastern New Mexico. The Permian’s tight oil plays have seen a significant rise in activity compared to newer production areas such as the Eagle Ford Shale and Williston Basin (which contains the Bakken Shale) since 2013, when the practice of horizontal drilling combined with fracking began in earnest.

While many operators in the area still conduct vertical drilling instead of or in addition to horizontal drilling, the use of horizontal drilling in the Permian Basin is gaining momentum. According to a recent report from the U.S. Energy Information Administration (EIA), by the end of 2013 the Permian Basin accounted for half of the total increase in horizontal drilling in the United States and was operating 215 oil-directed horizontal rigs, compared to the Eagle Ford Shale with 173 rigs and the Williston Basin with 164 rigs. During the first quarter of 2014, the number of Permian Basin rigs increased at a rate more than four times the increase in the Eagle Ford and Williston Basin.

The Permian Basin, named for the Permian Period which occurred 250 to 300 million years ago, is approximately 250 miles wide and 300 miles long and contains various fields stacked on top of each other, most notable the Spraberry, Wolfcamp, and Bone Spring formations which range from a few hundred to tens of thousands of feet deep. In addition to oil and natural gas, the Permian Basin is a major source of potash and sulfur.

Even though tight oil production is well underway in the Permian Basin and many of the sweet spots have been identified, challenges remain to maximize well productivity. Volumes of stratigraphic and lithographic data must be translated to form reservoir characterization models to determine which areas are most favorable to hydrocarbon production. Portable x-ray fluorescence (XRF) analyzers are emerging as extremely useful tools in both conventional and unconventional oil and gas exploration & production (E&P) for data collection and interpretation.

XRF technology can be used to analyze a variety of sample types common in the upstream E&P industry, including drill cuttings, cores, surface outcrops, and piston-cored sediments that are used in the exploration of hydrocarbons. Because the inorganic chemistry, and ultimately the mineral composition of the rocks, give geologists important information about how the hydrocarbon is hosted within the rock and how it will be produced, the elemental analysis of those rocks is critical. Portable XRF cannot analyze hydrocarbon fluids, but it can analyze bulk elemental chemistry (including major and trace elements) of a reservoir that reflects properties that influence porosity, permeability, fracturability, and productivity.

With this rapid on-site real time elemental analysis capability anywhere in the field, portable XRF analyzers can produce volumes of valuable geochemical data. Now portable XRF analyzers are available that can transfer this data to mobile GIS software to be translated into maps or logs to identify areas for more detailed investigation.

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