Abstract Hyperspectral core imaging as a commercial technology is fairly new to the oil and gas industry, providing a rapid and non-destructive method for mapping mineralogy of drill core and cuttings. The technology makes use of infrared spectrometers that collect imagery across the visible, near infrared, short-wave infrared and thermal (long-wave) infrared range that contains information related to a variety of mineral species, and in some cases including mineral chemistry and texture. In this paper we illustrate how the mineralogical information can be used directly for a variety of applications relevant to reservoir quality, including mineral mapping, sedimentological mapping and upscaling of micro information to the well scale. Statistical analysis allows the data to be used to segment cores into different rock types, and via calibration to quantitative mineralogical techniques, the data can be used to construct continuous curves of quantitative mineralogy, total organic content and production parameters.

Abstract Faults have complicated shapes. Non-planarity of faults can be caused by variations in failure modes, which in turn are dictated by mechanical stratigraphy interacting with the ambient stress field, as well as by linkage of fault segments. Different portions of a fault or fault zone may experience volume gain, volume conservation and volume loss simultaneously depending on the position along a fault's surface, the stresses resolved on the fault and the associated deformation mechanisms. This variation in deformation style and associated volume change has a profound effect on the ability of a fault to transmit (or impede) fluid both along and across the fault. In this paper we explore interrelated concepts of failure mode and resolved stress analysis, and provide examples of fault geometry in normal faulting and reverse faulting stress regimes that illustrate the effects of fault geometry on failure behaviour and related importance to fluid transmission. In particular, we emphasize the utility of using relative dilation tendency v. slip tendency on fault patches as a predictor of deformation behaviour, and suggest this parameter space as a new tool for evaluating conduit v. seal behaviour of faults.

ABSTRACT The northern segment of the Edwards (Balcones Fault Zone) Aquifer is an important source of water for municipalities, industry, and landowners in central Texas. Rapid population growth in this part of Texas has increased interest in the north segment of the aquifer and heightened concerns about groundwater availability. The aquifer consists of Cretaceous limestone stratigraphic units that crop out along its western margin and dip toward the east. Groundwater primarily flows from the aquifer outcrop recharge zones toward discharge zones along perennial rivers and streams in the outcrop area and to a lesser extent toward deeper parts of the aquifer, eventually discharging by cross-formational flow to overlying stratigraphic units, such as the Del Rio Clay, Buda Limestone, and Austin Chalk. Groundwater isotope compositions in the aquifer indicate that groundwater flow is most active in the unconfined parts of the aquifer and that most recharge occurs during late fall and winter months, even though highest monthly precipitation occurs during the spring. Pumping from the northern segment of the Edwards (Balcones Fault Zone) Aquifer is ~6.8 × 10 7 L/d, having peaked at ~1.0 × 10 8 L/d in 2004, but still up from ~3.4 × 10 7 L/d in the 1980s. Most of this pumping (~90%) is for municipal uses. However, in the rural northern and heavily urbanized southern parts of the aquifer, domestic and manufacturing uses, respectively, account for a significant portion of total pumping.

ABSTRACT The Uvalde Pool comprises the western portion of the San Antonio segment of the Edwards (Balcones Fault Zone) Aquifer. Assessment of available data on the hydrogeology of Uvalde County confirms the conceptualization that the Edwards Aquifer in Uvalde County to the west of the city of Knippa acts as a partially separate groundwater basin. This portion of the Edwards Aquifer is referred to as the Uvalde Pool. The Edwards Aquifer to the east of the Uvalde Pool is referred to as the San Antonio Pool. A constriction in groundwater flow between the two pools, referred to as the Knippa Gap, and marked differences in groundwater elevations on either side of the Knippa Gap are the motivation to treat the Uvalde and San Antonio Pools as separate hydrogeological features. The Uvalde Pool is unique because it is the only place where the Edwards Aquifer is in hydraulic communication with the overlying and younger Buda Limestone and the Austin Chalk Aquifers. Given the karstic nature of the Edwards Aquifer in the Uvalde Pool and its relatively limited spatial extent, the Uvalde Pool is characterized as a highly transmissive aquifer, but with relatively limited storage capacity.

Abstract: Identification of the best sequence of planktonic foraminiferal events that is reproducible across the Coniacian–Santonian boundary interval is determined by comparison of data from three reference sections: the Cantera de Margas section at Olazagutia in northern Spain (Global Boundary Stratotype Section and Point [GSSP] for the base of the Santonian Stage), the Ten Mile Creek section in southern Texas (candidate GSSP stratotype for the base of the Santonian Stage), and Tanzania Drilling Project (TDP) Site 39 drilled in Tanzania. In the stratotype section, the GSSP is marked by the lowest occurrence of the inoceramid Cladoceramus undulatoplicatus (= Platyceramus undulatoplicatus ), which occurs within the planktonic foraminiferal Dicarinella asymetrica Zone, and by secondary microfossil events and a negative 0.3‰ excursion in δ 13 C. The same bio- and chemostratigraphic records have been identified in the Ten Mile Creek section in Texas. In Tanzania, Globotruncana linneiana , a GSSP secondary planktonic foraminiferal marker event, has been used in the absence of Cl. undulatoplicatus and of correlative chemostratigraphic tie points. The planktonic foraminiferal composition in the three stratigraphic sections is similar, although discrepancies are observed in the reproducibility of some bioevents. Similarities between sections include the same order of appearances of the index species Sigalia carpatica , Costellagerina pilula , and G. linneiana in the Cantera de Margas section and TDP Site 39, and the absence of the single-keeled globotruncanids ( Globotruncanita stuartiformis , Globotruncanita elevata ) in the Cantera de Margas and Ten Mile Creek sections. This apparent diachronism mostly pertains to the paleobiogeographic distributions and ecological preferences of species that developed and diversified under specific paleoenvironmental conditions. Overall, the study of the three sections allows derivation of a more accurate and reproducible sequence of planktonic foraminiferal events across the Coniacian–Santonian boundary interval. It demonstrates the reliability of the surface dweller C. pilula as the best proxy for recognition of the base of the Santonian Stage from epicontinental to open-ocean depositional settings and in a wide range of paleolatitudes.