US 6,441,618 B2 · Method and apparatus for monitoring the advance of seawater into fresh water aquifers near coastal cities

Abstract

Sensors are permanently placed in the ground near observation and injection wells in order to passively and continuously monitor the status of seawater advance toward fresh water aquifers near coastal cities as well as the status of fresh water injected into the injection wells. Such sensor devices are installed in the ground and electrically connected to surface acquisition equipment that would, without human intervention, transmit acquired data to a centralized facility for processing and interpretation. Various types of sensors can be used: the sensors used for general reservoir monitoring and/or the sensors used for leak detection, soil heating, and temperature mapping. Alternatively, a special type of sensor can be designed and provided for the purpose of monitoring the status of seawater advance toward fresh water aquifers.

Claims20

Dependent claims

A method of passively and continuously monitoring a status of seawater advance toward fresh water aquifers which are located adjacent coastal cities, one or more observation wells being located in the fresh water aquifers adjacent said coastal cities, comprising the steps of:

installing sensors in or around said observation wells,
using said sensors, monitoring the advance of said seawater toward said fresh water aquifers.

A method of monitoring an advance of seawater toward a fresh water aquifer, an observation well penetrating said fresh water aquifer, said observation well having a casing, comprising the steps of:

locating a resistivity array within or around said casing of said observation well, an aquifer being located around said resistivity array;
using said resistivity array, measuring a resistivity value or a conductivity value of a water based substance in said aquifer around said resistivity array, the values of said resistivity or conductivity being representative of a presence or an absence of either seawater or fresh water in said water based substance in said aquifer.

A method of using an observation well which penetrates a water aquifer in an earth formation that is located near coastal cities to measure and obtain data representative of a characteristic of the water in said aquifer, said observation well having water disposed therein, comprising the steps of:

(a) locating an electrode inside said observation well, a depth of said electrode in said observation well being known;
(b) using said electrode, determining when a level of said water in said observation well traverses said electrode thereby determining a free head level of said water in said observation well through knowledge of said depth of said electrode in said observation well;
(c) locating a resistivity array within or around a casing of said observation well, said casing being disposed within said water aquifer in said earth formation;
and
(d) using said resistivity array, determining a resistivity of a water based substance disposed around said casing within said aquifer, said resistivity being representative of a presence or absence of seawater in said aquifer and being determinative of any advance of said seawater into said aquifer.

2 more elements

Dependencies are inferred from the claim text.

Method and apparatus for monitoring the advance of seawater into fresh water aquifers near coastal cities

Life of this patent

Method and apparatus for monitoring the advance of seawater into fresh water aquifers near coastal cities

Life of this patent

Abstract

Claims20