Publishing Venue
The IP.com Prior Art Database
Abstract
With a significant portion of the oil and gas industry currently exploring and exploiting unconventional reservoirs, certain processes and procedures that may have been at one time a reliable standard are now less adequate for evaluating the wide range of new reservoir challenges that have emerged in recent years. Many of the shales that are hydraulically stimulated are higher in clay content and often lower in material hardness than more conventional sandstones and carbonates. Evaluating proppant conductivity for a given stimulation treatment, frequently relies on the interpretation of data from a conductivity cell test to determine which proppant type, size, and amount will provide the best and most economical results for the hydraulic fracture treatment. In selecting the core wafers for the testing, it is not uncommon that the testing will use either: 1) a generic core that is commercially available such as Ohio Sandstone, or 2) a series of cores taken from the actual formation in which proposed fracture treatment will be placed. In several instances with the unconventional reservoirs of today, both of these testing procedures are insufficient to adequately discern the proppant with optimal performance. The generic cores, though often very uniform in the consistency of its rock properties, are typically a far deviation from the geomechanical rock properties expected in the targeted reservoir. Actual core from the reservoir, which is much more costly to obtain, is intrinsically a closer match to the expected geomechanical rock properties. However, actual core is subject to the lithological heterogeneity common in unconventional reservoirs, which creates an additional variable when testing proppant, and causes a dependence of the testing results on the quality of the chosen core sample, rather than solely on the proppant pack. A change in testing procedure to use synthetic core wafers manufactured specifically to match certain mechanical properties, would allow repeatable testing results that allow for a closer representation of the actual reservoir intended for the hydraulic fracturing treatment.
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Enhanced Conductivity Cell Testing to Provide Repeatable Results that Emulate Expected Proppant Embedment
Abstract
With a significant portion of the oil and gas industry currently exploring and exploiting unconventional reservoirs, certain processes and procedures that may have been at one time a reliable standard are now less adequate for evaluating the wide range of new reservoir challenges that have emerged in recent years. Many of the shales that are hydraulically stimulated are higher in clay content and often lower in material hardness than more conventional sandstones and carbonates. Evaluating proppant conductivity for a given stimulation treatment, frequently relies on the interpretation of data from a conductivity cell test to determine which proppant type, size, and amount will provide the best and most economical results for the hydraulic fracture treatment. In selecting the core wafers for the testing, it is not uncommon that the testing will use either: 1) a generic core that is commercially available such as Ohio Sandstone, or 2) a series of cores taken from the actual formation in which proposed fracture treatment will be placed. In several instances with the unconventional reservoirs of today, both of these testing procedures are insufficient to adequately discern the proppant with optimal performance. The generic cores, though often very uniform in the consistency of its rock properties, are typically a far deviation from the geomechanical rock properties expected in the targeted reservoir. Actual core from the reservoir, which is much more costly to obtain, is intrinsically a closer match to the expected geomechanical rock properties. However, actual core is subject to the lithological heterogeneity common in unconventional reservoirs, which creates an additional variable when testing proppant, and causes a dependence of the testing results on the quality of the chosen core sample, rather than solely on the proppant pack. A change in testing procedure to use synthetic core wafers manufactured specifically to match certain mechanical properties, would allow repeatable testing results that allow for a closer representation of the actual reservoir intended for the hydraulic fracturing treatment.
Description
Proppant conductivity testing and evaluation is an important part of optimizing a hydraulic fracturing treatment design for a given reservoir formation. The type of proppant used in the treatment will have an effect on the extent of the various conductivity damaging mechanisms that occur to the proppant pack. In conductivity cell testing, as well as several other proppant qualifying procedures, industry standardized processes are in place to help ensure processes are accurate and repeatable regardless of the laboratory they are performed in (Kaufman et al., 2007). In conductivity cell testing, proppant is placed between two core wafers, and under an elevated stress and elevated temperature environment, the cond...
