Diagenetic Controls on Reservoir Character of the Lower Permian Wolfcamp and Bone Spring Formations in the Delaware Basin, West Texas

2020 ◽  
Author(s):  
Arwin Dobber ◽  
Robert Goldstein
Keyword(s):  
Lower Permian ◽  
Delaware Basin ◽  
West Texas

Eustatic controls on stratigraphy, chemostratigraphy, and water mass evolution preserved in a Lower Permian mudrock succession, Delaware Basin, west Texas, USA

2015 ◽  
Vol 3 (1) ◽  
pp. SH11-SH25 ◽  
Author(s):  
Hardie S. Nance ◽  
Harry Rowe
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Sea Level ◽  
Elemental Content ◽  
Lower Permian ◽  
Central Basin ◽  
Sea Level Changes ◽  
Delaware Basin ◽  
West Texas ◽  
Central Basin Platform

Bone Spring (Leonardian) mudrock successions in Delaware Basin vary between silica- and carbonate-rich facies marking depositional responses to sea-level changes. Increased Mo, [Formula: see text], and total organic carbon (TOC) record reduced oxygenation during sea-level lowstands. In a 91.4-m (300 ft) core from Sun No. 1 Houssels well and a 39.6-m (130 ft) core from Shell No. 1 Marsden well (Reeves Co., Texas), lower Bone Spring cycles comprised siliceous-calcareous mudrock couplets. The Marsden core was correlative to the upper part of the Houssels core. Cyclicity was interpreted from mineralogical calculations at numerous core horizons using energy-dispersive X-ray fluorescence (ED-XRF) measurements of elemental content. Elemental abundances enabled predicting mineralogy based on the stoichiometric relationships between elements and dominant minerals (calcite and quartz), and from average values of Si and K in published illite analyses. The average sample spacing for ED-XRF measurements was 0.24 m (0.8 ft) for the Houssels core and 0.15 m (0.5 ft) for the Marsden core. The measurements and interpretations provided: (1) information regarding comparisons in stratigraphic and geographic development of facies over the 10-km (6.2-mi) distance between wells and (2) guidance for petrographic, scanning electron micrograph, and organic matter analyses that address processes that produced different facies. Greater carbonate abundance in the Houssels core reflected the proximity to carbonate shelves on the Central Basin Platform (CBP); the greater siliciclastic abundance in the Marsden core was thought to reflect the greater distance from the CBP. Redox element (S and Mo) and TOC concentrations were greater, and [Formula: see text] values were higher in some siliciclastic-dominated intervals, suggesting that anoxia characterized sea-level lowstands when normal marine water flowing from the Panthalassa Ocean was inhibited through narrow interbasin channels or over sills. Carbon isotope ([Formula: see text]) variations suggested changes in organic matter characteristics, whereby greater [Formula: see text]-depleted organic matter was deposited during sea-level lowstands, marking: (1) reduction of shallow-marine sources or (2) increased terrigenous organic carbon contributions.

LITHOFACIES, DIAGENESIS AND RESERVOIR QUALITY EVOLUTION OF WOLFCAMP SANDSTONE-SILTSTONE SUCCESSIONS IN DELAWARE BASIN, WEST TEXAS

2016 ◽  
Author(s):  
Ziyuan Wang ◽  
◽  
Hualing Zhang ◽  
Hualing Zhang ◽  
Yue Dong ◽  
...  
Keyword(s):  
Reservoir Quality ◽  
Delaware Basin ◽  
West Texas

Complex Shear-Wave Anisotropy from Induced Earthquakes in West Texas

2020 ◽  
Vol 110 (5) ◽  
pp. 2242-2251 ◽  
Author(s):  
Regan Robinson ◽  
Aibing Li ◽  
Alexandros Savvaidis ◽  
Hongru Hu
Keyword(s):  
Shear Wave ◽  
Induced Seismicity ◽  
High Rate ◽  
Normal Faults ◽  
Permian Basin ◽  
Induced Earthquakes ◽  
Large Delay ◽  
Delaware Basin ◽  
West Texas ◽  
Shallow Earthquakes

ABSTRACT We have analyzed shear-wave splitting (SWS) data from local earthquakes in the Permian basin in west Texas to understand crustal stress change and induced seismicity. Two SWS parameters, the fast polarization direction and the delay time, are computed using a semiautomatic algorithm. Most measurements are determined in the Delaware basin and the Snyder area. In both regions, SWS fast directions are mostly consistent with local SHmax at stations that are relatively far from the earthquake clusters. Varying fast directions at one station are related to different ray paths and are probably caused by heterogeneity. In the Snyder area, most northeast–southwest fast directions are from the events in the northern part of the cluster, whereas the northwest–southeast fast directions are mostly from the southern part. The northeast–southwest and northwest–southeast fast directions could be attributed to the northeast-trending normal faults and the northwest-trending strike-slip faults, respectively. SWS results in the Delaware basin have two unique features. First, most shallow earthquakes less than 4 km deep produce relatively large delay times. This observation implies that the upper crust of the Delaware basin is highly fractured, as indicated by the increasing number of induced earthquakes. Second, diverse fast directions are observed at the stations in the high-seismicity region, likely caused by the presence of multiple sets of cracks with different orientations. This situation is possible in the crust with high pore pressure, which is expected in the Delaware basin due to extensive wastewater injection and hydraulic fracturing. We propose that the diversity of SWS fast directions could be a typical phenomenon in regions with a high rate of induced seismicity.

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