Drilling Methods Used by the Western Region Research ... · PDF fileDrilling MethodsDrilling...
Transcript of Drilling Methods Used by the Western Region Research ... · PDF fileDrilling MethodsDrilling...
Three-dimensional geohydrologic and geochemical framework analysesrequire reliable subsurface data. This includes collecting Geologic,Geophysical, Hydrologic, and Geochemical data. The Western RegionResearch Drilling Program (WRRDP) collects these data in all types of geologic environments using multiple drilling methods, geophysicallogging of holes, and installation of wells and other instruments.
Logging and ConstructionMud DrillingAir Drilling
Wireline Coring
Monitoring
Drilling MethodsDrilling MethodsUsed by the Western Region Research Drilling ProgramUsed by the Western Region Research Drilling Program
Steven CrawfordU.S. Geological SurveyWestern RegionHenderson, Nevada
Core barrel retrieved Barrel broken down Liner with core removed from barrel
Coring sample
Noimage
Scale incentimeters
205 feetScale: In feet
below landsurface
206 feet
207 feet
208 feet
209 feet
210 feet
Western Region Research Drilling Program drill rig
Wireline coring is the most efficient method for collecting cores. Cores collected using this method greatly enhance subsurface data. Using the wireline system, cores can be taken continuously, or the drill-ahead system can be used if cores are taken intermittently. The WRRDP drill rig is capable of continuous coring a hole, then switching over to traditional drill pipe to ream the hole for instrumentation.
Note: Spring retract allows core barrel to protrude beyond cutting bit in soft zones. This protects the core from mud or air invasion.
Latching up to core barrel
5-foot barrel attached to5-foot spring retract
Hoisting core barrel upto line up over wireline casing
Core barrel being tripped down hole
Extraction of liner containing core material
Proper handling and recording of core is critical prior to lab analysis.
Wireline Coring
Liner is cut and core is described
Foot interval samples show dramatic changes on small scale.
Measuring EC and Cl
Simple onsite measurementsplotting chloride profile
Cores can be immediately sealed airtight. Chemical and physical properties of the core material can then be analyzed in the lab.
Air-hammer drilling is used in hard rock and unconsolidated-unsaturated studies. Unsaturated studies use an air-hammer/under-reamer system that pulls casing down as the hole is drilled. This allows wells and instrumentation to be installed inside the casing before the casing is pulled out of the hole. Reverse air circulation is also a method offered by the WRRDP.
Cores in saturated and unsaturated zones can be taken using the push-core barrel. Two-foot cores can be analyzed for both physical and chemical properties.
The rig's 900 cfm/350 psi air compressor forces the cuttings to the surface through the diverter to the cyclone. The cyclone allows air to escape upwards while cuttings drop out through the bottom. For larger diameter holes, a backup unit can be piggy backed to the rig's compressor for additional air volume.
Drilling site using air-hammer drilling method
Casing jacks"push" casingback out ofhole with 50,000 pounds of force.
8-inch threaded casing(6-inch is also availablefor use with this system)
Air swivel diverter directs cuttings tocyclone
Air hammer
Guide device
Air
Cuttings
Cyclone
Under reamerand pilot bit
Air Drilling
Drill bit
The pickup pump "vacuums" mud and cuttings from the borehole and diverts them to the shaker or mud-filtering system.
The shaker tank serves as the mud filtration system. Once filtered the mud is then pumped back down the borehole.
Typical cuttings collected by sieving mud and/or samplingfrom the shaker screen and cones.
Dual positive displacement (piston) mud pumps force the drilling fluid down the borehole when the rig's centrifugal pump is over pressured.
These pumps are used at deeper depths.
Both Direct and Reverse mud circulation methods are offered by the WRRDP. Direct mud circulation allows the scientist to collect both sieve and shaker samples. Spot coring is also possible. This method allows for rapid drilling of larger diameter holes and reaming of pilot holes. Flooded Reverse circulation uses either mud or water + polymers and air. Samples obtained using this method are very clean and accurate.
The shaker screen separates drilling mud from coarser cuttings.
The desilter cones or desander separate the finer sands from
drilling mud.
Reliable grout seals are set using a high-pressure positive displacement piston grouter.
Mud pumps
Stabilizer
Drill bit
Stabilizer
Drill pipeor collar
Fluid pathFluid path
Mud Drilling
Reverse circulation dual wall pipe
Heat dissipation probes
Wires attached to two advanced tensiometers and seven heat dissipation probes
Instruments are wired to data-logger
0 10 200
300
600
900
1,200
1,500
0 100 200 -50 100 250 0 75 150 0 75 150 0 200 400
Caliper,in
inches
DEP
TH F
ROM
LA
ND
SU
RFA
CE, I
N F
EET
Gamma,in counts
per second
SP,in
millivolts
SpontaneousPotential Resistivity Resistivity
Electro-MagneticInduction
(Conductivity)
16-inch,in ohms
per meter
64-inch,in ohms
per meter
EM,in millimhos
per meter
Geophysical logs and lithologic informationWell site 4S/12W-25G 1-6 (Long Beach water 1)
0 5,000 10,000
Vs and Vpvelocity, infeet per sec
GROUT
GRO
UT
GRO
UT
SAN
DSA
ND
SAN
D
4 3215 6Fill
Silty sand
Silty sandSilty sand withcoarse beds
Silty sand
Silty sand
Silty sand
Sand
Sand
Sand
Sand
Coarse sand
Coarse sand
Sandy siltBedded siltwith sandlayers
Bedded siltwith sandlayers
Sand
Silty muddy sand
LithologyWell
construction
SAND
SCREENEDINTERVAL
0
300
600
900
1,200
1,500
Dep
th fr
om L
and
Surf
ace,
in F
eet
Instrumentation installed in borehole at Artificial Recharge Pond tracks downward migration of recharge through an unsaturated zone.
Well (piezometer)covered by rag
Well construction and instrumentation is performed by the WRRDP. For ground-water studies, typical construction well nests include five to six individual monitoring wells. The screened interval of each well is surrounded by a sand pack. Seals are pressure grouted into place between screened zones.
Installation of unstaturated zone study instrumentation, such as neutron logging access tubes, gas-sampling tubes, psychrometers, temperature probes, and lysimeters, are standard procedure for the WRRDP. Seismometers and strain meters can also be installed for earthquake studies.
Geophysical logging services are included in all holes the WRRDP drills. Logs are printed onsite and digital files can be e-mailed to project managers. Standard logging tools which accompany the van include the following: resistivity tool (16-inch, 64-inch, lateral gamma, SP, temp., fluid resistivity), electromagnetic induction tool (conductivity, gamma, in open or fluid-filled hole), caliper tool, and deviation tool or inclinometer. Special tools can also be also run such as the acoustic televiewer, sonic (density), spectral gamma, and the borehole camera.
Inside of van showing computer used to run logging and plotting software
Geophysical tools used
Drawworks comes with2500 feet of cable
Resistivity
Deviation
ComputerPrinter
Caliper
EMinduction
Borehole Geophysical Logging Well Construction
Logging and Construction
0
50
100
150
200
250
300
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400O-02 D-02 M-03 J-03 S-03 D-03 M-04 J-04 S-04 D-04 M-05 J-05
Date
Dep
th, i
n fe
et
Position of wetting frontAdvanced tensiometersHeat dissipation probesElectromagnetic logs
Downward movement of wetting front at VVWD recharge pond along Oro Grande Wash near Victorville, southern California
downward rate of movement ~ 0.27ft/d
From J.A. Izbicki San Diego Ca.
EM Logs forWell CM2
mS/m
Feet
Feet
CM2 EM Log1994 & 1996
Change(1994 – 1996)
CM2 EM Log1994 & 1996
Change(1994 – 1996)
100
200
300
400
500
600
700
800-800mS/m 8000
mS/m 800-800mS/m 8000
The EM log conductivitydecreased in well CM2
at 150 to 240 feet belowland surface, indicating
a retreat of theseawater front.
Feet
Feet
100
200
300
400
500
600
700
800
900
Q2 EM Log1994 & 1996
Change(1994 – 1996)
Q2 EM Log1994 & 1996
Change(1994 – 1996)
mS/m0 600 mS/m-600 600
mS/m0 600 mS/m-600 600
EM Logs forWell Q2
The EM log conduc-tivity increased
in well Q2 at800 to 850 feet
below land surface,reflecting continued
water-qualitydegradation in the
lower aquifer systemin this area.
EM data are proven with data from instruments installed in the
borehole.
Changes in EM logs over time show the downward movement of
the wetting front
The WRRDP has experience in monitoring via geophysical logging. Two examples below demonstrate the ability of Electromagnetic Induction logs (EM logs) to track both fresh water recharge through the unsaturated zone in a desert environment and seawater intrusion in coastal environments. Temperature and flow metering are other very useful logs that can be run repeatedly over time.
For more information on this USGS program contact:Steven Crawford (702) 564-4541 or e-mail: [email protected]
Monitoring
A comparison of EM logs done in 1994 (red) and 1996 (blue) shows the changes that occurred during the 2-year period.