Research Article
Modeling Method of Braided River Delta Reservoir Configuration Based on Flow Unit
Dai Baixiang*
,
Yang Zhaoqiang,
Chen Kui,
Huan Jinlai,
Wang Qingshuai
Issue:
Volume 14, Issue 2, April 2025
Pages:
49-56
Received:
6 February 2025
Accepted:
27 February 2025
Published:
6 March 2025
DOI:
10.11648/j.earth.20251402.11
Downloads:
Views:
Abstract: The complex fault block oilfield in Weixinan Sag is gradually entering the middle and late development stage and the middle and high water cut stage. The complex contradictions among layers, within layers and in the plane result in low efficiency of injection water waves, complex distribution of oil and water, and difficult to accurately predict the distribution of remaining oil. The fine characterization of the internal configuration of the reservoir was carried out to characterize the strong heterogeneity of the continental sedimentary complex fault block reservoir, and the flow unit was subdivided to qualitatively characterize the differences in the reservoir quality of sand bodies at different stages in the vertical direction of the reservoir, which brought new challenges to the fine geological modeling of the reservoir. In view of the lack of well data in offshore oil fields, sedimentary laws and geological knowledge base summarized in previous studies are used to constrain the modeling of braided river delta reservoir configuration. Taking Weizhou C Oilfield as an example, sequential indication, object, truncated Gauss Multipoint geostatistics isophase modeling method is preferred to establish underwater distributary channel model based on target method. The truncated Gaussian simulation method can effectively characterize the characteristics of the transition zone, establish the flow unit model, use the flow unit constraint attribute model to establish, further calculate the reservoir heterogeneity coefficient, accurately characterize the reservoir heterogeneity, and lay a good foundation for the next step of reservoir numerical simulation and tapping the potential of remaining oil.
Abstract: The complex fault block oilfield in Weixinan Sag is gradually entering the middle and late development stage and the middle and high water cut stage. The complex contradictions among layers, within layers and in the plane result in low efficiency of injection water waves, complex distribution of oil and water, and difficult to accurately predict th...
Show More
Research Article
Geology and Petrography of Rawayya and Its Environs Part of Sheet 54SE, Bungudu Local Government Area of Zamfara State, Nigeria
Bello Aliyu*,
Zakariya Muhammad
Issue:
Volume 14, Issue 2, April 2025
Pages:
27-41
Received:
26 October 2024
Accepted:
13 January 2025
Published:
21 March 2025
DOI:
10.11648/j.earth.20251402.12
Downloads:
Views:
Abstract: The area of study is Rawayya and its environs, North Eastern Bungudu. An area of 15km² bounded by latitude 12°14'17" to 12°13'19" N and longitude 06°42'7" to 06°42'32" E was mapped on a scale of 1: 25,000. The area is accessed through major roads, footpaths, and river channels. The study area was mapped using the traverse method done with the aid of a topographical map, G. P. S (Global Positioning System), Hand lenses, Tape, compass clinometers, sack bags, and hammers to locate position, collect samples, take structural readings and store samples. Two major rock types were identified in the area. The rocks within the area comprise biotite-granite and granodiorite. The minerals identified through hand specimen field description of these rocks include: quartz, feldspar (plagioclase), biotite, and muscovite. Structures within the study area manifest an imprint of Pan-African orogeny (NNE-SSW). There was the presence of monomineral quartz veins. Other structures observed were faults, folds, joints (open and closed fractures), veins, xenoliths, and pegmatite veins. The predominant trend of the joints and veins is in the NE-SW direction. These structural features have been interpreted to be related to the Pan-African orogeny. The Petrographical analysis of the rock sample was carried out at Abubakar Tafawa Balewa University Bauchi. Using a Petrographic microscope (Thin section) identified major elements such as quartz, feldspars (plagioclase), biotite mica, muscovite, and accessory minerals such as Hornblende.
Abstract: The area of study is Rawayya and its environs, North Eastern Bungudu. An area of 15km² bounded by latitude 12°14'17" to 12°13'19" N and longitude 06°42'7" to 06°42'32" E was mapped on a scale of 1: 25,000. The area is accessed through major roads, footpaths, and river channels. The study area was mapped using the traverse method done with the aid o...
Show More
Research Article
Earthquake Source Parameters of Moderate to Small Earthquake and Scaling Relationships in the Western Himalaya: Seismic Hazard Implication
Vedprakash Thakur,
Sanjay Kumar Prajapati*,
Birendra Pratap,
Uma Shankar,
Sudipto Bhattacharje
Issue:
Volume 14, Issue 2, April 2025
Pages:
42-62
Received:
13 February 2025
Accepted:
28 February 2025
Published:
21 March 2025
DOI:
10.11648/j.earth.20251402.13
Downloads:
Views:
Abstract: The Northwest Himalayas experiences frequent seismic activity, with numerous moderate events occurring over the past century, leading to several disasters. In the present study, we conducted a comprehensive analysis of the source parameters for 125 earthquakes with local magnitudes (ML) ≥ 4.0 that occurred in the northwest region during the period from 2013 to 2019. We analyzed the P and S wave spectra using Brune's source model to investigate the self-relation and self-similarity of earthquakes in the area. The digital seismograms used in this study were recorded by sixteen permanent broad-band stations at hypocentral distances between 10 and 327 km. The average ratio of P/S wave corner frequency is found in the range of 1.1-1.9, suggesting a higher corner frequency for the P wave. The static stress drops range from 0.1 and 136 MPa with a median value of 9.8 MPa (98 bars). The obtained seismic moments range from 7.49×1014 to 1.15×1018 Nm (4.0 ≤ Mw ≤ 6.0). The source radii are between 388 and 7073 m. we established a linear relationship between local and moment magnitudes. The scaling relations obtained indicated a slight deviation from self-similarity. High-stress drops observed in some events suggest elevated frictional strength and lower strain rates within faults, while lower stress drops may indicate general fault weakness. Although a definitive correlation between seismic moment and static stress drop was not observed universally, some events with lower seismic moment values also demonstrated lower stress drops. Furthermore, the corner frequency decreased with increasing seismic moment, with a slight depth dependence observed; shallower events tended to have higher corner frequency values than deeper ones. While there wasn't a clear depth dependence of stress drop values, a more pronounced depth dependence of seismic moment was observed, indicating that deeper events generally have larger seismic moment values in our study area. This implies that large earthquakes could still leave significant stress on faults, potentially leading to future events. The present study also reveals that Mw is lower than ML for all earthquakes with magnitudes > 4.0. The coefficient of determination of the magnitude fit scale is found to be 0.91, which indicates the fit is good. Therefore, it is concluded that the newly derived magnitude scale is more consistent than the currently used ML scale for the study region.
Abstract: The Northwest Himalayas experiences frequent seismic activity, with numerous moderate events occurring over the past century, leading to several disasters. In the present study, we conducted a comprehensive analysis of the source parameters for 125 earthquakes with local magnitudes (ML) ≥ 4.0 that occurred in the northwest region during the period ...
Show More
