Browsing by Subject "Permian Basin"
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Item Authigenic clays and stylolites in the carbonate reservoirs of the Permian Basin(Texas Tech University, 1997-05) Kumar, AnishAuthigenic clay minerals are found in back-reef carbonate rocks ofthe Upper Permian Artesia Group ofthe northwestern shelf of the Delaware Basin. The authigenic clays are located in the vugs and pore spaces of the carbonates. Stylolites from these rocks do not show clays of authigenic origin, however detrital clays and other minerals such as illite, quartz, feldspar, and pyrite are accumulated in the stylolite seams in these carbonates. Authigenic clays in pores and vugs of carbonate samples were studied using x-ray diffraction, and electron imaging such as SEM, TEM, and STEM. Dickite is the predominant authigenic clay mineral. It occurs mostly in euhedral hexagonal platelets. Authigenic illite is rarely observed, and it occurs as laths and fibers.Item Correlating petrophysical and flood performance in the Levelland slaughter field(2005-05) Watson, Marshall C.; Lawal, Akanni S. L.; Heinze, Lloyd R.The Levelland and Slaughter fields combined have produced over 1.6 billion bbls from 1937 to date from 6000 wells and currently produce 6% of the oil in Texas. Most of the field is under water and CO2 flood operations. This project investigates reservoir and petrophysical characteristics of various areas in the Levelland Slaughter field in order to assess relation to performance of secondary and tertiary recovery. The benefits would be to use this relationship to identify depositional environment/facies where little to no core data exists. In areas where no flood has been installed, the relationships developed herein could assist in the ability to predict flood recovery and the method of development. The Levelland Slaughter field is similar to several other ramp type, carbonate fields in the Permian Basin. Results once applied and proved successful in the Levelland Slaughter field not only could be applied to many other fields in the Permian Basin, but also to similar oil reservoirs all over the world. The first objective was to divide the field into areas of like depositional environments. This entailed identifying depositional environments via log, core and production analysis. The objective is to integrate geology and production into the study to ascertain whether like data can be considered, especially in an east west sequence across Levelland Slaughter. There are three depositional environments at Levelland Slaughter as follows; shelf with shoals, lagoonal and intertidal/near shore. Once subdivided, relationships between petrophysical properties and secondary recovery rates are developed utilizing Lucia’s rock fabric classification and production plot methods demonstrated by Reza Fassihi of BP. Fassihi demonstrated the method of plotting water cut against fractional secondary oil recovered enabled one to derive the matrix/fracture flow and storage capacity relationships. Based on curves developed by Fassihi, one can conclude there is little to no natural fracturing in the reservoirs in the Levelland Slaughter field. Lucia demonstrated that by plotting porosity against permeability in carbonate reservoirs, one could derive the type of rock fabric and detect facies changes. Net pay for primary and secondary recovery can be different and are dependent primarily on permeability and water saturation. Water saturation varies within the pay zone in lower permeability reservoir rock. Below a given permeability, water saturation increases and become movable. In consideration of the fore going, a typical Levelland well in the 1950’s produced water free, but later, prior to waterflooding, produces 20 to 50% water cut. For secondary waterflood recovery considerations, a critical water saturation exist where an oil bank does not develop, thus resulting in prolong recovery periods or little to no recovery from that particular reservoir rock. From the Lucia classification and Fassihi plots, it appears that most of the rock fabrics are similar and only differ in permeability. This is possibly due to anhydrite inclusion that was deposited in the more permeable rock, thus leaving the lower permeability mudstone porosity intact. Some localized areas could have improved reservoir due to subtle changes in elevation. These elevation changes are critical in the western area because small sea level changes caused substantial areas to go from subtidal to intertidal to supratidal/mud flats. Each of the fore mentioned steps resulting in a reduction in reservoir quality due to salt precipitation or anhydrite inclusions. This does not apply to shoal areas, located at shelf margins, because they were never supratidal, thus there are no evaporates. Thus the higher permeability rock demonstrates higher primary recoveries as well as much greater Secondary to Primary ratios (S:P).Item Correlating petrophysical and flood performance in the levelland slaughter field(Texas Tech University, 2008-05) Watson, Marshall C.; Lawal, Akanni S. L.; Heinze, Lloyd R.The Levelland and Slaughter fields combined have produced over 1.6 billion bbls from 1937 to date from 6000 wells and currently produce 6% of the oil in Texas. Most of the field is under water and CO2 flood operations. This project investigates reservoir and petrophysical characteristics of various areas in the Levelland Slaughter field in order to assess relation to performance of secondary and tertiary recovery. The benefits would be to use this relationship to identify depositional environment/facies where little to no core data exists. In areas where no flood has been installed, the relationships developed herein could assist in the ability to predict flood recovery and the method of development. The Levelland Slaughter field is similar to several other ramp type, carbonate fields in the Permian Basin. Results once applied and proved successful in the Levelland Slaughter field not only could be applied to many other fields in the Permian Basin, but also to similar oil reservoirs all over the world. The first objective was to divide the field into areas of like depositional environments. This entailed identifying depositional environments via log, core and production analysis. The objective is to integrate geology and production into the study to ascertain whether like data can be considered, especially in an east west sequence across Levelland Slaughter. There are three depositional environments at Levelland Slaughter as follows; shelf with shoals, lagoonal and intertidal/near shore. Once subdivided, relationships between petrophysical properties and secondary recovery rates are developed utilizing Lucia’s rock fabric classification and production plot methods demonstrated by Reza Fassihi of BP. Fassihi demonstrated the method of plotting water cut against fractional secondary oil recovered enabled one to derive the matrix/fracture flow and storage capacity relationships. Based on curves developed by Fassihi, one can conclude there is little to no natural fracturing in the reservoirs in the Levelland Slaughter field. Lucia demonstrated that by plotting porosity against permeability in carbonate reservoirs, one could derive the type of rock fabric and detect facies changes. Net pay for primary and secondary recovery can be different and are dependent primarily on permeability and water saturation. Water saturation varies within the pay zone in lower permeability reservoir rock. Below a given permeability, water saturation increases and become movable. In consideration of the fore going, a typical Levelland well in the 1950’s produced water free, but later, prior to waterflooding, produces 20 to 50% water cut. For secondary waterflood recovery considerations, a critical water saturation exist where an oil bank does not develop, thus resulting in prolong recovery periods or little to no recovery from that particular reservoir rock. From the Lucia classification and Fassihi plots, it appears that most of the rock fabrics are similar and only differ in permeability. This is possibly due to anhydrite inclusion that was deposited in the more permeable rock, thus leaving the lower permeability mudstone porosity intact. Some localized areas could have improved reservoir due to subtle changes in elevation. These elevation changes are critical in the western area because small sea level changes caused substantial areas to go from subtidal to intertidal to supratidal/mud flats. Each of the fore mentioned steps resulting in a reduction in reservoir quality due to salt precipitation or anhydrite inclusions. This does not apply to shoal areas, located at shelf margins, because they were never supratidal, thus there are no evaporates. Thus the higher permeability rock demonstrates higher primary recoveries as well as much greater Secondary to Primary ratios (S:P).Item Facies, depositional environments, and reservoir properties of the Shattuck sandstone, Mesa Queen Field and surrounding areas, southeastern New Mexico(Texas A&M University, 2004-09-30) Haight, JaredThe Shattuck Sandstone Member of the Guadalupian age Queen Formation was deposited in back-reef environments on a carbonate platform of the Northwest Shelf (Permian Basin, New Mexico, USA) during a lowstand of sea level. At Mesa Queen Field, the Shattuck Sandstone is a sheet-like sand body that averages 30 ft (9.1 m) in thickness. The Shattuck Sandstone includes deposits of four major siliciclastic environments: (1) fluvial sandflats, (2) eolian sand sheets, (3) inland sabkhas, and (4) marine-reworked eolian sands. Fluvial sandflat deposits are further subdivided into sheetflood, wadi plain, and river-mouth deposits. Dolomites, evaporites, and siliciclastics that formed in adjacent coastal sabkha and lagoonal environments bound the Shattuck Sandstone from above and below. The Shattuck Sandstone is moderately- to well-sorted, very fine-grained subarkose, with a mean grain size of 98 ?m (3.55?). Eolian sand sheet, wadi plain, and marine-reworked eolian facies comprise the productive reservoir intervals. Reservoir quality reflects intragranular and intergranular secondary porosity formed by partial dissolution of labile feldspar grains, and pore-filling anhydrite and dolomite cements. Vertical successions and regional facies patterns support previous interpretations that these deposits formed during a sea-level lowstand and early stages of the subsequent transgression. Facies patterns across the shelf indicate fluvial sandflats prograded over coastal and continental sabkhas, and eolian sand deposition became more common during sea-level fall and lowstand. During subsequent transgression, eolian sediments in the upper portion of the Shattuck Sandstone were reworked as coastal and lagoon environments became reestablished on the inner carbonate platform.Item Regional analysis of Residual Oil Zone potential in the Permian Basin(2014-08) West, Logan Mitchell; Tinker, Scott W. (Scott Wheeler)This study provides independent analysis of Residual Oil Zones (ROZs) in the Permian Basin from a regional perspective, focusing on the formation mechanism and present ROZ locations. Results demonstrate widespread potential for ROZs, defined here as thick volumes of reservoir rock containing near-residual saturations of predominantly immobile oil formed by natural imbibition and displacement of oil by dynamic buoyant or hydrodynamic forces. Previous work suggests hydrodynamic forces generated by regional tectonic uplift drove widespread oil remobilization and ROZ creation. To test the hypothesis, uplift and tilting are quantified and the resulting peak regional potentiometric gradient used as a physical constraint to compute and compare predicted ROZ thicknesses from hydrodynamics for several ROZ-bearing San Andres fields with known ROZ thicknesses. Late-Albian Edwards Group geologic contacts, which are interpreted to have been deposited near sea level prior to uplift, are used as a regional datum. Approximate elevations determined for the present datum show ~1800 m of differential uplift since Edwards deposition, with an average regional slope of ~0.128˚. This post-Edwards tilting increased the pre-existing regional structural gradient of the San Andres Formation to ~0.289˚. Using the calculated post-Edwards gradient results in to prediction of ROZ thicknesses from hydrodynamics that is consistent with measured ROZ thicknesses at several fields. When compared with countervailing buoyancy forces, hydrodynamics is calculated to be the more dominant driving force of oil movement for reservoirs with structural dips less than 1.5˚, which is the common dip for San Andres Formation platform deposits where ROZs have been identified. To predict the location of ROZs, ROZ-related oil field properties were identified and analyzed for over 2,800 Permian Basin reservoirs. A strong basin-wide correlation between API and crude sulfur content is consistent with the expected outcome of oil degradation driven by oil-water interaction, and supports the use of API and sulfur content as proxies for ROZ potential in the Permian Basin. Spatial analysis of sulfur data shows that the highest probability for ROZ existence exists in Leonardian through Guadalupian-age reservoirs, distributed primarily in shelf and platform areas of Permian structures. Combined, these results support the widespread potential for ROZs across the Permian Basin generated primarily by regional scale tilting and resultant hydrodynamic forces.