One of the most common subsurface data sets that is easily accessible and often underutilized is the acquired measuring while drilling (MWD) gamma ray (GR-GAPI) log. Data is acquired from a given gamma ray tool positi...One of the most common subsurface data sets that is easily accessible and often underutilized is the acquired measuring while drilling (MWD) gamma ray (GR-GAPI) log. Data is acquired from a given gamma ray tool positioned within the drill string and pulsed up to the surface through the mud column in the wellbore. Typical use of the data is for subsurface geologists, drillers and others to correlate the data to known stratigraphic signatures and steer wells through horizontal target zones. Through that correlation, an association to the geologic stratigraphic column can be made and the team of subsurface scientists adjusts where, how fast, and why they choose to continue drilling. The technique of correlation applies to both the conventional and unconventional application. In the unconventional ap</span><span style="font-family:Tahoma;font-size:12px;">plication, the data is also typically acquired along the length of the horizontal wellbore. From</span><span style="font-family:Tahoma;font-size:12px;"> a petrophysical standpoint, just acquiring a gamma ray can limit the amount of information </span><span style="font-family:Tahoma;font-size:12px;">and ability to fully evaluate the properties along the length of the well. In this study, we share</span><span style="font-family:Tahoma;font-size:12px;"> and demonstrate how to utilize the MWD GR for petrophysical evaluation beyond just a volume of shale or volume of clay interpretation. The workflow will allow full integration of a comprehensive petrophysical evaluation that can then be utilized to support all subsurface understandings and modelling efforts.展开更多
Barbed tributaries flowing in southeast directions, an asymmetric drainage divide with both the South Fork Grand River and the North Fork Moreau River, and the Jump-off escarpment-surrounded basin (interpreted here to...Barbed tributaries flowing in southeast directions, an asymmetric drainage divide with both the South Fork Grand River and the North Fork Moreau River, and the Jump-off escarpment-surrounded basin (interpreted here to be a large abandoned headcut) are examples of topographic map evidence suggesting the north oriented Little Missouri River valley eroded headward across a large southeast oriented anastomosing complex of ice-marginal melt water flood flow channels that once crossed Harding County, South Dakota. Additional evidence includes southeast oriented tributaries to the northeast oriented South Fork Grand River and multiple divide crossings (e.g. through valleys and wind gaps) on the Boxelder Creek-Little Missouri River divide (in eastern Montana and west of the Little Missouri River) and suggests deep regional erosion occurred as the north oriented Little Missouri River valley eroded headward into and across the region. Harding County is located south and west of the southwest limit of coarse-grained glacial erratic material and ice-marginal melt water flow routes logically should have crossed it. Deep melt water erosion of Harding County and adjacent eastern Montana regions to the west is not consistent with many previous drainage history and glacial history interpretations, but is consistent with deep erosion by continental ice sheets.展开更多
文摘One of the most common subsurface data sets that is easily accessible and often underutilized is the acquired measuring while drilling (MWD) gamma ray (GR-GAPI) log. Data is acquired from a given gamma ray tool positioned within the drill string and pulsed up to the surface through the mud column in the wellbore. Typical use of the data is for subsurface geologists, drillers and others to correlate the data to known stratigraphic signatures and steer wells through horizontal target zones. Through that correlation, an association to the geologic stratigraphic column can be made and the team of subsurface scientists adjusts where, how fast, and why they choose to continue drilling. The technique of correlation applies to both the conventional and unconventional application. In the unconventional ap</span><span style="font-family:Tahoma;font-size:12px;">plication, the data is also typically acquired along the length of the horizontal wellbore. From</span><span style="font-family:Tahoma;font-size:12px;"> a petrophysical standpoint, just acquiring a gamma ray can limit the amount of information </span><span style="font-family:Tahoma;font-size:12px;">and ability to fully evaluate the properties along the length of the well. In this study, we share</span><span style="font-family:Tahoma;font-size:12px;"> and demonstrate how to utilize the MWD GR for petrophysical evaluation beyond just a volume of shale or volume of clay interpretation. The workflow will allow full integration of a comprehensive petrophysical evaluation that can then be utilized to support all subsurface understandings and modelling efforts.
文摘Barbed tributaries flowing in southeast directions, an asymmetric drainage divide with both the South Fork Grand River and the North Fork Moreau River, and the Jump-off escarpment-surrounded basin (interpreted here to be a large abandoned headcut) are examples of topographic map evidence suggesting the north oriented Little Missouri River valley eroded headward across a large southeast oriented anastomosing complex of ice-marginal melt water flood flow channels that once crossed Harding County, South Dakota. Additional evidence includes southeast oriented tributaries to the northeast oriented South Fork Grand River and multiple divide crossings (e.g. through valleys and wind gaps) on the Boxelder Creek-Little Missouri River divide (in eastern Montana and west of the Little Missouri River) and suggests deep regional erosion occurred as the north oriented Little Missouri River valley eroded headward into and across the region. Harding County is located south and west of the southwest limit of coarse-grained glacial erratic material and ice-marginal melt water flow routes logically should have crossed it. Deep melt water erosion of Harding County and adjacent eastern Montana regions to the west is not consistent with many previous drainage history and glacial history interpretations, but is consistent with deep erosion by continental ice sheets.
