Summary:
Local Geology
General Stratigraphy Surficial geologic units overlying the area in and around the Crane Operation are predominantly comprised of undifferentiated Quaternary Age unconsolidated deposits, ranging from aeolian (windblown) sheet sands and dunes to alluvial sands, silts, clays, and caliche. Geologic mapping shows additional surficial stratigraphic units present in the vicinity of the project; however, the surface geology in and around the Crane Operation is primarily comprised of these aeolian sand deposits.
Exploration completed on the Crane property indicate two surficial sand units being present, an upper clean sand unit (dune and sheet sands) and an underlying clayey cover sand unit (Judkins Formation). The following text discusses the strata encountered in and around the Crane Operation, in depositional order:
-Fredericksberg Group A thick unit of limestone, dolomite, marl, and caliche, which represents the basal unit encountered at the Crane Operation. An unconformity separates this unit from the overlying Judkins formation, which differs significantly in age.
-Judkins (Blackwater Draw Equivalent) Formation The Judkins Formation is a brownish-red, argillaceous (clay-rich) sand body consisting of fine- to medium-grained quartz which may be silty and calcareous. This formation represents the first major period of dune building to affect the area and includes minor amounts of interdune pond sediments.
-Quaternary Sheet and Dune Sands Most of the subject property is covered by Quaternary sheet and dune sands generally consisting of fine- to medium-grained quartz sand grains, mixed with varying degrees of clays and silts.
The structural features of the Quaternary sands in and around the Crane Operation are relatively non-descript. While the unit exhibits variable thickness over the area, it is unaffected by folding or faulting. Underlying the surficial sand units is the limestone basal unit, which defines the mineable limit of the sands on and around the subject property. Due to the lack of structural features encountered, there are no known geological features that are believed to materially affect a proppant sand mining operation in the immediate area; as such, the deposit is considered to be of low geologic complexity.
Surficial geologic units overlying the Crane Operation are predominantly comprised of undifferentiated Quaternary age unconsolidated deposits, ranging from aeolian (windblown) sheet sands and dunes to alluvial sands, silts, clays, and caliche. The top 12 in. of the sand unit is generally contaminated with surface debris and organic content and is considered overburden.
The surface sands on the property consist of two distinct intervals that are both mineable sand: 1) an upper loose sand unit, and 2) a lower “sandstone” unit. Underlying the total mineable surface sand deposits is the hard, limestone basal unit which commonly results in the presence of caliches. The upper sand as generally consisting of unconsolidated, fine- to medium-grained, well sorted and subangular to rounded sand grains, ranging in thickness from 13 to 46 ft. The clean sand is noted as containing generally less than 15% fine (clay) material. The lower sand is described as a clayey, hard sandstone interval, with very fine- to medium-grained, subangular to rounded sand grains, ranging in thickness from 0 to 25 ft. The lower sand is noted having a higher (15–45%) clay content. The two sand units are generally mineable from the ground surface down to the basal limestone unit. Combined thickness of both sand units ranges from 10 to 80 ft across the property.
The sand mined at the Crane Operation is processed to produce proppant sand. Proppant sand is a naturally occurring, high silica content quartz sand with grains that are generally well-rounded. The main difference between proppant sand and other sands is that proppant sand grains are relatively pure in composition and consisting almost entirely of quartz; other sands have numerous impurities that may be cemented to the quartz grains. The pure quartz composition of proppant sand grains, along with being well-rounded and spherical in shape, gives these sands the characteristics (crush strength, high acid solubility, low turbidity) that are sought after by oil and gas producers for use in developing wells.