Unconventional/complex reservoirs

Unconventional Shale Reservoirs Meet Cancer Genome Sequencing

A case study presented at ATCE took medical science to a new low—into the depths of the Permian Basin for application to downhole reservoir drainage diagnostics.

Digital screen with DNA strands and data background. Double helix structure. Nucleic acid sequence. Genetic research. 3d illustration.
Source: JuSun/Getty Images/iStockphoto.

The cross-industry development and application of technologies is the epitome of innovation and ingenuity. The more divergent the industries are, the more the unique ways of thinking strike us as remarkable.

Technology transfer between the oil and gas industry and other sectors isn’t new. Many examples can be found in medical science, space exploration, and renewable and sustainable technologies. In this JPT issue, the technologies of Oceaneering Space Systems and Impossible Sensing Energy are featured.

A case study presented at the 2023 SPE Annual Technical Conference and Exhibition took medical science to a new low—into the depths of the Permian Basin for downhole reservoir drainage diagnostics (RDD).

The coauthors, a subsurface and wells manager and a chapter manager, surveillance, analysis, and optimization and pilots at Chevron Technology Ventures (CTV), described using genome sequencing for cancer detection and treatment in a successful proof-of-concept (POC) test conducted from 2017 to 2019.

Nampetch Yamali and Daniel Emery explained in SPE 215052 how in 2017 CTV was given the task of identifying technology to assess vertical drainage dimensions to estimate drainage volumes from fractured wells. The goal was to minimize interference from offset wells and co‑developments to optimize reservoir recovery in unconventional fields.

At that time, the technologies and their capabilities were limited. Although subsurface microbial DNA sequencing for upstream assets has found applications in enhanced biocide and corrosion inhibition, reservoir sweet spot indicators, and tracer technology, use of the technique was thought also to have potential in horizontal well development planning via RDD.

Learning of a genomic sequencing technique for cancer cell identification in humans at the biology and biochemistry department at the University of Houston, the wheels started turning at CTV with thoughts it could be developed and adopted for RDD.

Similarities were seen because RDD uses in-situ subsurface microbial DNA to infer the depths from which fluids drain after fracturing a horizontal well and optimizes well spacing on a pad, especially in stacked reservoirs.

The predictive analytics platform mapped the hydrocarbon footprints of geologic subzones by using noninvasive DNA testing tools. The unique DNA markers for RDD were extracted from mud and cuttings from the horizontal and vertical drilling sections. DNA from produced fluids was also collected.

The authors wrote, “Produced fluids collected at two-to-four-week intervals at the wellhead are mapped to the RDD framework. They are ‘lineage traced’ back to shale and tight rock. Drainage heights and percentage of contribution from these locations is computed adapting DNA sequencing and data analytics pipelines which were developed for lineage tracing cancer cells, breaking off from the primary tumor and metastasizing to distant sites back to the tissue of origin.”

After validating the DNA extractions, CTV conducted a blind test using only the DNA data to determine the landing zones for each of the four wells in the pad. Using clustering methods, the results of the blind test accurately identified all landing zones within an acceptable margin, according to Yamali and Emery.

The next step in the trial analyzed the DNA of the produced fluids. “Preliminary results showed drainage height estimates for each horizontal well.”

In 2021, the study continued with an additional four new field trials in the Permian Basin for application of the technique to zonal production identification. The authors wrote, “Although the results from the POC were positive, subsurface DNA RDD technology is a novel technique within the oil and gas industry, and advanced applications are still evolving. This combination naturally gives rise to more general skepticism and a need to thoroughly evaluate the technology from operational, economic, and accuracy perspectives.”

The paper describes the ongoing cross-disciplinary work being done by petroleum engineers, geologists, microbiologists, and stratigraphers to fully evaluate this method of RDD. It further details CTV’s wider approach to “accelerate the innovation life cycle, from pilot stages to widespread adoption at scale,” emphasizing the need for leaders’ support for nonconventional thinking and approaches.

As the close of 2023 approaches, I’d like to take this opportunity to wish you the best in 2024 on behalf of the JPT Editorial Review Board and the JPT staff.

We’ll be kicking off the new year with the commemoration of JPT’s 75th anniversary. Each issue will include an article dedicated to the evolution of technology and industry practices over the seven and a half decades JPT has covered the upstream industry. In January, Trent Jacobs and Stephen Rassenfoss will revisit technological advancements since JPT’s 50th anniversary in 1999. Since then, over 25 million B/D have been added to the global supply thanks in very large part to advancements in drilling, completions, and reservoir technologies. Join us as we explore these along with some predictions made 25 years ago and the surprising realities of where the industry stands today.