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A novel technology (electrokinetics) is proposed to improve acidizing operations, i.e., increase the penetration distance. The acid dissolves the carbonates (limestones/dolomites), enlarging the pores and increasing the width of pre-existing fractures. This gives rise to an increase in permeability. The principal acid commonly used is hydrochloric (HCl), which is pumped through tubing. Aqueous solutions of hydrochloric acid (usually 15%) are pumped into the carbonate formations to enlarge the pores and pre-existing fractures. Without application of D.C. current, the penetration distance is usually very short, especially in tight rocks. However, the penetration distance of acid is very short. By applying D.C. current, one can drive the acid for long distances into the formation being acidized.
In this paper, we present a malicious node detection scheme using
confidence-level evaluation in a grid-based wireless sensor network. The sensor
field is divided into square grids, where sensor nodes in each grid form a
cluster with a cluster head. Each cluster head maintains the confidence levels
of its member nodes based on their readings and reflects them in
decision-making. Two thresholds are used to distinguish between false alarms
due to malicious nodes and events. In addition, the center of an event region
is estimated, if necessary, to enhance the event and malicious node detection
accuracy. Experimental results show that the scheme can achieve high malicious
node detection accuracy without sacrificing normal sensor nodes.