Traditional drill pad construction techniques for natural gas production displace the existing plant community and result in surface disturbances requiring costly soil remediation and revegetation procedures. At the Jonah natural gas field, Sublette County, Wyoming, EnCana Oil and Gas (U.S.A.), Inc. is evaluating the use of oak mats to minimize disturbance to soil and plant resources by facilitating drilling and completion activities atop continuous 15.2 centimeter thick oak platforms. One concern with both traditional and oak mat drill pad construction techniques is the potential for increases in soil bulk density. In this study, dry soil bulk density was measured before-and-after oak mat drill pad construction at 17 drill pad sites for 0-5.1, 0-15.2 and 0-30.5 centimeter depth increments to quantify changes in soil bulk density in relation to growth limiting bulk densities described in the literature. Similar bulk density measurements were taken at six conventional-reclaimed drill pads to allow comparison between the construction techniques. Of the 17 oak mat locations, four drill pad areas exhibited no statistically significant change in bulk density as a result of the oak mat procedure. Of the 13 remaining oak mat drill pads, one or more depth increments had significant soil bulk density increases of 0.06 to 0.17 g/cm 3 as a result of drilling on top of the oak mats. Literature review indicated plant growth may be impaired when the dry soil bulk density is greater than 1.5 g/cm 3. Of the oak mat soil profile depths measured, 95 % remained below this value, while a substantially higher proportion of conventional-reclaimed drill pad soil profile depths exceed this threshold.
Traditional drill pad construction techniques for natural gas production involve a cut-and-fill procedure that displaces existing plant communities and results in costly soil remediation and revegetation procedures. At the Jonah natural gas field, Sublette County, Wyoming, EnCana Oil and Gas (USA), Inc. is evaluating use of oak mats during drilling and completion activities to minimize disturbances to soil and plant resources. In this study, changes in vegetation and soil attributes were evaluated as a result of oak mat use. Overall, oak mats tended to protect plant resources, minimize weedy forb establishment and maintain the plant community in a condition similar to adjacent rangeland. On average when compared to native range, grass growth improved, forbs remained similar, and shrubs were negatively impacted in oak matted areas. Vegetative results suggest that the success and timeliness of reclamation following the use of oak mat drill pads is superior to that obtained at reclaimed cut and fill locations. Following mat removal, mean soil bulk density values changed -2.9, 2.2 and 3.7 percent for the 0 to 5.1, 0 to 15.3, and 0 to 30.5 cm depth increments. All soil bulk density values remained below recommended thresholds for rangeland environments. A costbenefit discussion indicates that in this setting, construction costs associated with oak mats are similar to those incurred by traditional cut-and-fill techniques. Drilling procedures using oak mats are more costly due to the need for a closed system for treatment of drill cuttings. However, this expense may be offset by lower reclamation costs associated with oak mat use.
dicting lime requirements are inadequate for evaluating ongoing acid production from acid rninesoils. The primary objective of this study was to develop a computerized automated rapid weathering apparatus (CARWA) that could determine. total, one-time application lime requirements for acid minesoils in a 24 hour time frame. Comparisons of CARWA lime recommendations to those determined by the laborious, time consuming manual laboratory weathering method indicate that rapid weathering is feasible.
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