The ability to gather and analyze data from unconventional oil and gas plays, of which the permeability is not fully understood, has become more critical as exploration and production companies pursue more unconventional oil and gas in the U.S. and worldwide.
Houston-based PetroArc International offers technology that allows producers to get a more accurate picture of the permeability and porosity of oil and gas reservoirs from core, plugs and cuttings, as well as the tools to analyze and store that data on a laptop computer.
Established in 2005 to provide high-quality, high-resolution imagery to the oil and gas and medical science industries, PetroArc’s approach to measuring permeability in oil and gas plays differs from other companies. Instead of flowing gas through a sample to estimate permeability, PetroArc’s approach involves analyzing permeability using image analysis.
Commonly used techniques for permeability measurement involve assessing the ease with which a fluid will flow through a clean, dry sample. Problems arise when the sample is fractured or otherwise incompetent because the fluid always takes the path of the least resistance. This means that the permeability measurement reads higher than it should be, said PetroArc President Christopher M. Prince. By using image analysis, PetroArc can estimate the permeability of core and core plugs using a methodology that doesn’t involve injecting a fluid, no cleaning or ovens, and can be completed in a shorter timeframe.
PetroArc’s approach has been successfully tested in shale plays such as the Barnett and Haynesville, as well as tight gas sands from Asia, and conventional plays in Africa and the Gulf of Mexico.
HDCuttings imagery was designed to address an underutilized resource for reservoir characterization: well cuttings. While they do not have precise depth control, well cuttings are good indicators of lithology, an inexpensive means for correlation in frontier terrains.
When examined at 40x magnification, well cuttings can be used for grain size analysis, composition, and when coupled with log-derived porosity, permeability. Recent work suggests that the shape of the cuttings may provide a way to distinguish between fractured and non-fractured zones within the well. Being able to analyze data from well cuttings and plugs is even more critical given that obtaining a sample from shale plays, which are fragile, can be a difficult task.
The company founders recognized that the type of high-resolution, large-format imaging and image analysis would be of little value without the appropriate tools. To take full advantage of this technology, the company developed several virtual microscope systems geared towards specific analytical tasks.
The company offers fully portable core scanners and staff that can be dispatched worldwide to handle an exploration and production company’s imaging needs. These scanners can image core at resolutions ranging from 300 to 11,000 dpi under both white and ultraviolet light.
PetroArc’s proprietary software, which can be installed on a laptop, also enables a company to archive information for analysis up to months and years after a project is complete. Their ‘TenEx’ core imagery is imaged at 1360 dpi, the equivalent of looking at the core through a 10x hand lens. As a standard image files, the imagery would be difficult to use, PetroArc uses a wavelet compression technology to reduce the file size by 95 percent without any noticeable loss in pixel resolution or color fidelity. This allows for a quick download onto a laptop for viewing.
Smaller producers who may not have access to the lab equipment for testing can utilize the company’s scanning services. A number of companies that can’t afford 3D seismic technology may be left to drill and hope for the best.
Once data is gathered, the company’s CORSystem provides unparalleled access to a company’s imagery and data. Like other software packages, CORSystem provides one-click access to well logs, plug data, and reports. Unlike other packages, the software bundles a virtual 40x hand lens for viewing core, a petrographic microscope for viewing thin sections, and a reflected light microscope for viewing core plugs and well cuttings. Each of these contains tools for performing descriptive and analytical tasks.
PetroArc’s MicroPet 3.0, contains all of the tools and capabilities of a standard petrographic microscope, as well as additional tools for analysis of the pore network. HDMicro 2.0, the virtual reflected-light microscope for examination of core plugs and cuttings, contains an array of tools designed to allow the user to rapidly assess grain size, texture, color and composition. It can be used with conventional imagery, but it was designed to be used with HDPlug or HDCuttings imagery ranging from 40x-80x magnification.
Karen Boman has more than 10 years of experience covering the upstream oil and gas sector. Email Karen at [email protected]