Samples of subsurface DNA taken from produced fluids or well cuttings provide a snapshot of the subsurface returning tens of thousands of DNA markers per sampling point.
INTEGRATION OF SUBSURFACE DNA AND DATA SCIENCE. From the initial analysis of Anadarko’s wells, the 174 fluid samples returned thousands of unique subsurface DNA markers.
A representative subsurface DNA log suite from a Delaware basin well summarizes DNA marker variation from more than 450 well cuttings samples taken at high spatial resolution along a single vertical wellbore.
Successful technology deployments through the Permian have involved collecting well cuttings from a vertical pilot well and applying this vertical DNA marker baseline to additional wells on the same pad.2,7 This successful project showcased that the formation end-members acquired from the vertical cuttings could be applied to wells on the same pad. UPSCALING TO FIELD-WIDE DEVELOPMENTS. For field-level development, an important factor to understand is the spatial resolution of that vertical baseline signal.
In a published case study with EP Energy in the Midland basin, subsurface DNA markers were used to determine the well that caused a frac hit.9 As part of a deployment of the subsurface diagnostics within the southern Midland basin acreage, produced fluids from six wells were collected before, and during, completions and flowback operations.
During the simultaneous frac operation of three child wells-well No. 4, well No. 5 and well No. 6-a pressure response was observed in a monitored parent well, which was well No. 2.
Subsurface DNA markers from well No. 2, before and after fracturing operations, were compared to the neighboring wells, to explore the similarity and extent of overlap of these DNA markers.