Mohammad O. Eshkalak

Geomechanical Properties of Unconventional Shale Reservoirs

Production from unconventional reservoirs has gained an increased attention among operators in North America during past years and is believed to secure the energy demand for next decades. Economic production from unconventional reservoirs is mainly attributed to realizing the complexities and key fundamentals of reservoir formation properties. Geomechanical well logs (including well logs such as total minimum horizontal stress, Poisson’s ratio, and Young, shear, and bulk modulus) are secured source to obtain these substantial shale rock properties. However, running these geomechanical well logs for the entire asset is not a common practice that is associated with the cost of obtaining these well logs. In this study, synthetic geomechanical well logs for a Marcellus shale asset located in southern Pennsylvania are generated using data-driven modeling. Full-field geomechanical distributions (map and volumes) of this asset for five geomechanical properties are also created using general geostatistical methods coupled with data-driven modeling. The results showed that synthetic geomechanical well logs and real field logs fall into each other when the input dataset has not seen the real field well logs. Geomechanical distributions of the Marcellus shale improved significantly when full-field data is incorporated in the geostatistical calculations.

An Economic Evaluation on the Re-fracturing Treatment of the U.S. Shale Gas Resources

We investigate the economic feasibility of the re-fracturing treatment of horizontal wells producing gas from unconventional reservoirs. As a result of advancements in horizontal completions and hydraulic fracturing, the U.S. has been able to economically develop several decades of worth of natural gas from shale deposits. However, a considerable concern has risen on the economic viability of shale gas development with the reasons associated to the very fast production declines as well as recent down-turns of natural gas prices beside the raise in additional costs of new technologies. Therefore, an economic analysis required to investigate the profitability of the secondary enhanced gas recovery method, re-fracturing treatment of unconventional gas resources within the U.S. Net present value (NPV) of cash flows and internal rate of return (IRR) are calculated for different assumed gas prices considering 20 years of natural gas production from a typical unconventional reservoir. A systematic comparison is made for three scenarios, 1) re-fracturing vs. no re-fracturing (the base case scenario) 2) combination of re-fracturing and drilling new well; and 3) time-dependent re-fracturing treatment. This paper incorporated the cost of re-fracturing treatment, the cost of drilling a new horizontal well, the water treatment cost, as well as the current and future price of natural gas in the model. Findings of this work can be used to optimally develop the U.S. shale gas assets. Moreover, operators can have access to an assessment to ensure the economic success of their unconventional horizontal wells in their future re-fracturing treatments.