The Westbay System is multilevel groundwater monitoring technology that allows sealing of multiple monitoring zones in one borehole for testing and monitoring purposes.
Casing
The delivery system consists of two sizes of casing which were developed to fit two ranges of borehole sizes.
MP38 System has an inside diameter of roughly 38mm (1.5in) and is generally used in boreholes or casing whose inside diameter ranges from 76mm (3in) to 115mm (4.5in).
MP55 System has an inside diameter (ID) of 55mm (2.25in) and is generally used in boreholes or casing whose ID ranges from 98mm (3.9in) to 170mm (6.25in).
Both systems are designed for operation at maximum depths that range from 300m (1,000ft) to over 1,500m (5,000ft).
Both systems are available in plastic and in stainless steel. Steel systems are used in situations where tensile strengths, hydraulic pressures or temperatures are higher than would be suitable for the plastic systems.
Regular Couplings
Couplings joining the casing together consist of regular couplings and port couplings. Regular couplings simply join two pieces of casing together, while port couplings provide a controllable pathway for formation fluids on the outside of the coupling to reach the inside of the coupling.
Measurement Ports
The measurement port is the heart of the MP System. Measurement ports are used for the majority of the pressure measurement and fluid sampling operations. Each measurement port coupling has a small check valve that contains a spring that keeps the valve closed so that it will not open due to the application of an exterior fluid pressure. The measurement port is operated by means of a MOSDAX* probe that is lowered into the borehole, locates the measurement port and opens the port valve.
Pumping Ports
In contrast to the measurement port, a pumping port coupling has several relatively large openings. The total area of these openings is approximately equal to the cross-sectional area of the inside of the casing. A sliding sleeve valve controls the pumping port openings. Either mechanical or hydraulic operating tools operate pumping port valves.
Packers
Different levels (monitoring zones) in a borehole are separated by placing impervious layers of backfill around the outside of the casing between monitoring zones or by using water inflated packers.
Westbay has developed a series of modular hydraulically inflated packers that are mounted on plastic or stainless steel mandrels. Each packer has an individual inflation valve attached to the packer. After the packers have been positioned in the borehole, a packer inflation tool is lowered into the borehole and packers are inflated individually.
Magnetic Collars
Magnetic collars can be attached to the outside of the casing near components that will be visited frequently. The collars contain ceramic magnets. When a probe passes by a magnetic collar, a reed switch in the probe is triggered and a "beeping" noise is heard at the surface. This assists the probe operator in determining the location of the probe in the borehole.
Specialized Components
A number of special components are available. These include:
Y-connectors that permit twin–tubes to be installed in the upper part of the drillhole. This arrangement permits pumping to occur in one tube while sampling and pressure monitoring occur in the other.
Telescopic casings that can extend or be compressed after installation. These protect the casing components should there be a tendency for the borehole to lengthen or shorten in the future.
A borehole completion kit that permits de-stressing of the plastic casing during installations in deep boreholes.
Tools for Casing Installation and Recovery
Packer Inflation Tools: Each casing system (MP38 and MP55) has a specific tool to inflate packers. These tools have associated winches, hoses and control units for handling the packer inflation activities.
Pumping Port Operating Tools: The operation of pumping ports requires tools that will open and close the pumping port valve. A separate mechanical "open/close" tool is available for the plastic MP38 System. Hydraulic pumping ports for the steel MP38 System and the MP55 System are operated by a modified MOSDAX sampling probe or by a special tool.
Casing Recovery Tools: Casing recovery tools are available for those projects where it is necessary to demonstrate recovery capability before installation proceeds.
Since its introduction in 1978, Westbay System has been used for a variety of applications around the world, including:
Groundwater basin management
Using Westbay System to construct a three-dimensional network of monitoring zones provides the data necessary to observe groundwater behavior on a "macroscopic" scale. This detailed data allows basin managers to optimize the use of groundwater resources.
Environmental and geological repository site characterization studies
Westbay System has been used in the nuclear waste research programs in Canada, the United States, Japan, Spain, the United Kingdom, Switzerland, France, and South Korea.
Scientists involved in studying the possibility of burying nuclear waste deep underground agree that the most likely pathway for radionuclides to return to the biosphere is through groundwater.
As a result, careful evaluation of groundwater conditions is critical to determine the feasibility of an underground disposal site. The detailed, defensible data collected through Westbay System provides the key to a thorough understanding of groundwater conditions at a proposed repository site.
Deep contaminant monitoring projects
Information on the vertical distribution of fluid pressures and chemistry is the key to characterizing, managing and remediating contaminated groundwater sites. Westbay System enables you to collect the data you need to identify the problem—affordably.
Geotechnical studies for landslides, ground settlement, mines, tunnels, and dams
Engineers and geologists involved in the geotechnical sector have received vital pore pressure data and water chemistry information using Westbay System technology on large construction projects that involve slope stability, dewatering and settlement.
Because fluid pressures and displacements are two of the most important parameters in the study of slope stability, Westbay System has been used on some of the largest landslide and slope stability studies ever undertaken.
Draw on our knowledge and experience to help you select equipment and develop well designs to meet your technical objectives, borehole conditions and Westbay System capabilities. We'll start by asking you about your project and help you select the best Westbay System components and type of borehole completion method for your particular situation. Our Westbay System casing can be installed in an open hole, through a temporary guide tube or in a cased well. The type of seals (e.g., packers) selected must match the drilling equipment and the expected borehole dimensions and stability conditions. Where packers are not used, monitoring zones can be sealed by backfill.
Field installation
Our on-site technician helps your installation proceed smoothly. We work with your field installation team according to a well-proven process:
Approve the monitoring well design.
Visually inspect and lay out the Westbay System casing components in sequence.
Record the serial numbers for each packer, measurement port, and pumping port.
Assemble each casing joint and test the hydraulic seals.
Lower the casing into the borehole.
Test the hydraulic integrity of the entire casing string.
Inflate the packers sequentially from bottom to top, recording the inflation pressure and volume of water used for each packer.
Measure fluid pressures at each measurement port to confirm proper operation and check the annular hydraulic seals between monitoring zones. When QA zones have been added between monitoring zones, pressure measurements in them help confirm packer seal quality.
Maintenance and repair
Westbay System monitoring well components require little maintenance. That said, we recommend that you invest in a comprehensive maintenance, service and QA program for the portable measurement and sampling equipment for good QA of monitoring data and to support their continued reliable operation. Our maintenance programs can include annual recalibration of sensors, parts replacement, and priority response when you require repairs.
Operator training
We'll train your field operators to meet our high standards and yours. We provide training in all aspects of operating Westbay wells, including:
Pressure profiling—with pressure probes or sampling probes.
Sample collection using a Westbay sampling probe and accessories.
Using pumping port open/close equipment and any pump supplied, if you plan to carry out purging.
Hydraulic testing using pumping ports.
Deployment, programming, downloading, and recovery of automated data acquisition equipment.
Operating procedures, QA checks, and routine equipment maintenance in the field.
QA testing and review
Our technical services staff can also advise you on quality assurance testing and evaluation and, upon request, will review your data to verify that your equipment is operating properly.
Westbay System casing is available in two sizes:
Westbay55 (55 mm ID): Install larger diameter casing deeper, providing you greater flexibility and upgrade potential.
Westbay38 (38 mm ID):Functions like Westbay 38 but with a smaller diameter.
Operational capability:
Variation of system size and material of construction provides operational capability ranging to depths of greater than 1,200 m (4,000 ft) in boreholes or wells ranging in size from 76 mm (3 inches) to 160 mm (6-1/4 inches) and larger. Varying well completion methods are available to meet specific project requirements and/or hydrogeologic environments.
Operating specifications can vary considerably from project to project. We can help you to choose the system that best meets your requirements.
Schlumberger Water Services provides innovative groundwater monitoring and sampling instruments, field data acquisition accessories, and software for environmental data management, analysis, visualization, conceptual modeling and simulations, with a complete range of training and support services for environmental consultants, government agencies, industry, and educational/research institutions.
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