The carbonate reservoir
quality is strongly reliant on the compaction
process during sediment burial and other processes such as cementation
and dissolution. Porosity and pore pressure are the two main factors
directly affected by mechanical and chemical compactions. Porosity
reduction in these carbonates is critically dependent on the overburden
stress and subsidence rate. A variable sediment influx in younger
basins may lead to changes in the reservoir quality in response to
increasing lithostatic pressure. Deposition of molasse sediments as
a result of the Himalayan orogeny caused variations in the sedimentation
influx in the Potwar Basin of Pakistan throughout the Neogene times.
The basic idea of this study is to analyze the carbonate reservoir
quality variations induced by the compaction and variable sediment
influx. The Sakesar Limestone of the Eocene age, one of the proven
carbonate reservoirs in the Potwar Basin, shows significant changes
in the reservoir quality, specifically in terms of porosity and pressure.
A 3D seismic cube (10 km2) and three wells of the Balkassar
field are used for this analysis. To determine the vertical and lateral
changes of porosity in the Balkassar area, porosity is computed from
both the log and seismic data. The results of both the data sets indicate
2–4% porosities in the Sakesar Limestone. The porosity reduction
rate with respect to the lithostatic pressure computed with the help
of geohistory analysis represents a sharp decrease in porosity values
during the Miocene times. Pore pressure predictions in the Balkassar
OXY 01 well indicate underpressure conditions in the Sakesar Limestone.
The Eocene limestones deposited before the collision of the Indian
plate had enough time for fluid expulsion and show underpressure conditions
with high porosities.
Wireless local area networks (WLANs), known as Wi-Fi, are widely deployed to meet the enhanced needs of data-centric internet applications, such as wireless docking, unified communications, cloud computing, interactive multimedia gaming, progressive streaming, support of wearable devices, up-link broadcasts and cellular offloading. Wi-Fi networks typically adopt the Distributed Coordination Function (DCF)-based Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA), which uses the Binary Exponential Back-off (BEB) algorithm at the MAC layer mechanism to access channel resources. Currently deployed Wi-Fi networks face huge challenges towards efficient channel access for denser environments due to the blind exponential increase/decrease of a contention window (CW) procedure that is inefficient for a higher number of contending stations. Several modifications and amendments have been proposed to improve the performance of the MAC layer channel access based on a fixed or variable CW size. However, a more realistic network density-based channel resource allocation solution is still missing. An efficient channel resource allocation is one of the most critical challenges for future highly dense WLANs, such as High-Efficiency WLAN (HEW). In this paper, we propose a Channel Collision-based Window Scaled Back-off (CWSB) mechanism for channel resource allocation in HEW. In our proposed CWSB, all contending stations select an optimized CW size for each back-off stage for collided or successfully transmitted data frames. We affirm the performance of the proposed CWSB mechanism with the help of an Iterative Discrete Time Markov Chain (I-DTMC) model. This paper evaluates the performance of our proposed CWSB mechanism in HEW Wi-Fi networks using an NS3 simulator in terms of the normalized throughput and channel access delay compared to the state-of-the-art BEB and a recently proposed mechanism.
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