U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2009–1017

In cooperation with the U.S. Department of Energy/National Nuclear Security Administration 

and Babcock & Wilcox Technical Services Pantex, LLC

Analysis of Vertical Flow During Ambient and Pumped 

Conditions in Four Monitoring Wells at the Pantex Plant, 

Carson County, Texas, July–September 2008
Front cover:

Left, U.S. Geological Survey and Pantex personnel and equipment setup for pumping flowmeter measurements at monitoring well site.

Right, Pantex-owned pump hoist equipment raising pipe-deployed submersible pump in monitoring well 

with electromagnetic flowmeter being supported in well by U.S. Geological Survey borehole geophysical 

unit.

Back cover: Measuring water level in monitoring well PTX06-1056 during pumping flowmeter measurements.
Analysis of Vertical Flow During Ambient 

and Pumped Conditions in Four Monitoring 

Wells at the Pantex Plant, Carson County, 

Texas, July–September 2008

By Gregory P. Stanton, Jonathan V. Thomas, and Jeffery Stovall

In cooperation with the U.S. Department of Energy/National Nuclear Security 

Administration and Babcock & Wilcox Technical Services Pantex, LLC

Open-File Report 2009–1017

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2009

For product and ordering information:

This and other USGS information products are available at http://store.usgs.gov/

U.S. Geological Survey

Box 25286, Denver Federal Center

Denver, CO 80225

To learn about the USGS and its information products visit http://www.usgs.gov/

1-888-ASK-USGS

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the 

U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Stanton, G.P., Thomas, J.V., and Stovall, Jeffery, 2009, Analysis of vertical flow during ambient and pumped conditions 

in four monitoring wells at the Pantex Plant, Carson County, Texas, July–September 2008: U.S. Geological Survey 

Open-File Report 2009–1017, 26 p.
iii

Contents

Abstract ..........................................................................................................................................................1

Introduction ....................................................................................................................................................2

Purpose and Scope .............................................................................................................................2

Description of Study Site ....................................................................................................................2

Hydrogeology ........................................................................................................................................2

Acknowledgments ...............................................................................................................................2

Methods of Borehole Geophysical Data Collection ................................................................................4

Electromagnetic Flowmeter ...............................................................................................................5

Fluid Resistivity/Temperature Logs ...................................................................................................5

Natural Gamma Logs ...........................................................................................................................7

Analysis of Vertical Flow .............................................................................................................................7

Monitoring Well PTX01–1012 .............................................................................................................7

Data Collected .............................................................................................................................7

Flow During Ambient and Pumped Conditions ......................................................................7

Monitoring Well PTX06–1044 .............................................................................................................9

Data Collected .............................................................................................................................9

Flow During Ambient and Pumped Flow Conditions Before Redevelopment ...................9

Flow During Ambient and Pumped Flow Conditions After Redevelopment ....................11

Monitoring Well PTX06–1056 ...........................................................................................................13

Data Collected ...........................................................................................................................13

Flow During Ambient and Pumped Flow Conditions Before Redevelopment .................13

Flow During Ambient and Pumped Flow Conditions After Redevelopment ....................15

Monitoring Well PTX06–1068 ...........................................................................................................15

Data Collected ...........................................................................................................................15

Flow During Ambient and Pumped Conditions ....................................................................16

Summary .......................................................................................................................................................16

References ...................................................................................................................................................17

Appendix 1—Flowmeter Analyses of Monitoring Wells With Flow–B Numerical Model Input 

and Results .....................................................................................................................................19

1.1. Monitoring Well PTX01–1012 .........................................................................................21

1.2. Monitoring Well PTX06–1044 Before Redevelopment ...............................................22

1.3. Monitoring Well PTX06–1044 After Redevelopment ..................................................23

1.4. Monitoring Well PTX06–1056 Before Redevelopment ...............................................24

1.5. Monitoring Well PTX06–1056 After Redevelopment ..................................................25

1.6. Monitoring Well PTX06–1068 .........................................................................................26

Figures

1. Location of the Pantex Plant, Carson County, Texas .............................................................3

2. Ogallala aquifer monitoring wells logged with flowmeter at the Pantex Plant, 

Carson County, Texas ..................................................................................................................4

3. (A) Diagram of flowmeter in borehole showing zones of differing hydraulic head 

and direction of flow in the borehole, and (B) photograph of Century Model 9721 

electromagnetic flowmeter with rubber diverter installed ...................................................6
iv

4. Borehole geophysical logs plotted with calculated transmissivity and well 

construction in screened intervals of monitoring well PTX01–1012 at the Pantex 

Plant, Carson County, Texas .......................................................................................................8

5. Borehole geophysical logs plotted with calculated transmissivity and well 

construction in screened intervals of monitoring well PTX06–1044 at the Pantex 

Plant, Carson County, Texas .....................................................................................................10

6. Borehole geophysical logs plotted with calculated transmissivity and well 

construction in screened interval of monitoring well PTX06–1056 at the Pantex 

Plant, Carson County, Texas .....................................................................................................12

7. Borehole geophysical logs plotted with calculated transmissivity and well 

construction in screened interval of monitoring well PTX06–1068 at the Pantex 

Plant, Carson County, Texas .....................................................................................................14

Table

1. Pertinent information for Ogallala aquifer monitoring wells logged at the Pantex 

Plant, Carson County, Texas, July–September 2008 ..............................................................5

Conversion Factors and Datums

Inch/Pound to SI

Multiply By To obtain

Length

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre 4,047 square meter (m2

)

Flow rate

gallon per minute (gal/min) 0.06309 liter per second (L/s)

Transmissivity1

foot squared per day (ft2/d) 0.09290 meter squared per day (m2/d) 

1 Transmissivity: The standard unit for transmissivity is cubic foot per day per square foot times foot of aquifer 

thickness ([(ft3/d)/ft2]/ft). In this report, the mathematically reduced form, foot squared per day (ft2/d), is used for 

convenience.

Datums

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Altitude, as used in this report, refers to distance above the vertical datum.
Abstract

The Pantex Plant is a U.S. Department of Energy/

National Nuclear Security Administration (USDOE/NNSA)-

owned, contractor-operated facility managed by Babcock & 

Wilcox Technical Services Pantex, LLC (B&W Pantex) in 

Carson County, Texas, approximately 17 miles northeast 

of Amarillo. The U.S. Geological Survey, in cooperation 

with B&W Pantex through the USDOE/NNSA, made a series 

of flowmeter measurements and collected other borehole 

geophysical logs during July–September 2008 to analyze 

vertical flow in screened intervals of four selected monitoring wells (PTX01–1012, PTX06–1044, PTX06–1056, and 

PTX06–1068) at the Pantex Plant. Hydraulic properties 

(transmissivity values) of the section of High Plains (Ogallala) aquifer penetrated by the wells also were computed. 

Geophysical data were collected under ambient and pumped 

flow conditions in the four monitoring wells. Unusually large 

drawdowns occurred at two monitoring wells (PTX06–1044 

and PTX06–1056) while the wells were pumped at relatively 

low rates. A decision was made to redevelop those wells, and 

logs were run again after redevelopment in the two monitoring 

wells. 

Logs collected in monitoring well PTX01–1012 during ambient conditions indicate a dynamic environment that 

probably was affected by pumping of nearby irrigation or 

public-supply wells. During pumping, downward vertical flow 

of 0.2 to 2.1 gallons per minute that occurred during ambient 

conditions was either reversed or reduced. During pumping, 

a gradual trend of more positive flowmeter values (upward 

flow) with distance up the well was observed. Estimated 

total transmissivity for four production zones identified from 

Flow–B numerical model results taken together was calculated 

to be about 3,100 feet squared per day. 

Logs collected in monitoring well PTX06–1044 during 

ambient conditions before redevelopment indicate a static 

environment with no flow. During pumping there was upward 

vertical flow at rates ranging from 0.1 to about 1.5 gallons 

per minute. During pumping, a gradual trend of more positive 

flowmeter values (upward flow) with distance up the well was 

observed. Estimated total transmissivity before redevelopment 

for five production zones identified from Flow–B numerical 

model results, and transmissivity values for each zone, are 

considered to be in error because of the lack of communication 

between the well and the aquifer before redevelopment. After 

redevelopment, logs for well PTX06–1044 during ambient 

conditions indicate a near-static environment with minimal 

downward flow. During pumping there was upward vertical 

flow at rates ranging from 0.5 to about 4.8 gallons per minute. 

During pumping, a gradual trend of more positive flowmeter 

values with distance up the well was observed. Estimated total 

transmissivity after redevelopment for the same five identified 

production zones taken together was calculated to be about 

520 feet squared per day. 

Logs collected in monitoring well PTX06–1056 during 

ambient conditions before redevelopment indicate a static 

environment with no flow. During pumping there was upward 

vertical flow at rates ranging from 0.3 to about 1.5 gallons 

per minute. During pumping, a gradual trend of more positive 

flowmeter values (upward flow) with distance up the well was 

observed. Estimated total transmissivity before redevelopment 

for four production zones identified from Flow–B numerical model results taken together was calculated to be about 

450 feet squared per day. After redevelopment, logs collected 

in monitoring well PTX06–1056 during ambient conditions 

indicate a near-static environment with no flow except for a 

very small amount of downward flow near the bottom of the 

well. During pumping there was upward vertical flow at rates 

ranging from 0.7 to about 2.9 gallons per minute. Estimated 

total transmissivity after redevelopment for five production 

zones identified from Flow–B numerical model results taken 

together was calculated to be about 330 feet squared per day. 

Logs collected in monitoring well PTX06–1068 during 

ambient conditions indicate a static environment with no flow. 

During pumping there was upward vertical flow at rates ranging from 0.4 to 4.8 gallons per minute. During pumping, 

a gradual trend of more positive flowmeter values (upward 

flow) with distance up the well was observed. Estimated 

total transmissivity for four production zones identified from 

Analysis of Vertical Flow During Ambient and Pumped 

Conditions in Four Monitoring Wells at the Pantex Plant, 

Carson County, Texas, July–September 2008

By Gregory P. Stanton, Jonathan V. Thomas, and Jeffery Stovall1 

1

 Babcock & Wilcox Technical Services Pantex, Amarillo, Texas. 
2 Analysis of Vertical Flow During Ambient and Pumped Conditions in Four Monitoring Wells at the Pantex Plant

Flow–B numerical model results taken together was calculated 

to be about 200 feet squared per day.

Introduction

The Pantex Plant is a U.S. Department of Energy/

National Nuclear Security Administration (USDOE/NNSA)-

owned, contractor-operated facility managed by Babcock & 

Wilcox Technical Services Pantex, LLC (B&W Pantex) in 

Carson County, Tex., approximately 17 miles northeast of 

Amarillo. The Pantex Plant was originally constructed by 

the U.S. Department of Army for production of conventional 

ordnance during World War II. The Pantex Plant was deactivated after the war and the property reverted to the War 

Assets Administration. Texas Technological College (now 

Texas Tech University [TTU], Lubbock) purchased the installation in 1949. The Army Ordnance Corps reclaimed the 

site in 1951 for use by the Atomic Energy Commission as 

a nuclear weapons facility. Today (2009) the mission of the 

Pantex Plant is to assemble nuclear weapons for the Nation’s 

stockpile; disassemble nuclear weapons being retired from 

the stockpile; evaluate, repair, and retrofit nuclear weapons 

in the stockpile; sanitize components from dismantled 

nuclear weapons; provide interim storage for plutonium pits 

from dismantled nuclear weapons; and develop, fabricate, 

and test chemical explosives and explosive components for 

nuclear weapons to support USDOE/NNSA initiatives (U.S. 

Department of Energy, 2009). The U.S. Geological Survey (USGS), in cooperation with B&W Pantex through the 

USDOE/NNSA, made a series of flowmeter measurements 

and collected other borehole geophysical logs during July–

September 2008 to analyze vertical flow in screened intervals 

of four selected monitoring wells at the Pantex Plant. Hydraulic properties (transmissivity values) of the section of High 

Plains (Ogallala) aquifer penetrated by the wells also were 

computed.

Purpose and Scope

The purpose of this report is to analyze vertical flow 

during ambient and pumped conditions in four monitoring wells at the Pantex Plant in Carson County, Tex., and to 

document the methods of collection of electromagnetic (EM) 

flowmeter data and fluid-resistivity, temperature, and natural 

gamma logs at the Pantex Plant during July–September 2008. 

The USDOE/NNSA contractor, B&W Pantex, identified the 

four wells open to the Ogallala aquifer for the analysis. The 

wells are constructed of 4-inch-diameter stainless steel casing 

and range in total depth below land-surface datum (LSD) from 

475 to 900 feet. Data were collected at various depths below 

LSD to assess the distribution of flow in screened intervals 

and compute transmissivity values for the adjacent section of 

Ogallala aquifer. Transmissivity values were computed using 

a numerical flow model developed for analysis of flowmeter 

data.

Description of Study Site

The Pantex Plant main area of operations is bounded 

on the north by Farm to Market Road (FM) 293, on the east 

by FM 2373, and on the west by FM 683 (fig. 1). Recently, 

USDOE/NNSA purchased 1,526 acres of land east of FM 

2373 to provide access for ground-water monitoring and 

positive control over future land and ground-water use (B&W 

Pantex, writtten commun., 2008). The Pantex Plant site now 

consists of a total of 17,559 acres, of which 5,856 acres 

owned by TTU constitutes a safety and security buffer. TTU 

leases the safety and security buffer property back to USDOE/

NNSA; Texas Tech Research Farm manages the buffer zone as 

rangeland and farmland. 

Hydrogeology

The primary subsurface geologic units at the Pantex 

Plant are the Triassic-age Dockum Group (sand to clay), the 

Tertiary-age Ogallala Formation (sand to silty sand), and 

the Quaternary-age Blackwater Draw Formation (clayey 

silts) (Holliday, 1989). The uppermost of two water-yielding 

units (aquifers) in the Ogallala Formation at the study site 

is perched at depths of approximately 200 to 300 feet below 

LSD. This unit is underlain by a zone of relatively low permeability, informally referred to as the fine-grained zone, which 

consists of silts and clays that retard the downward migration 

of perched water. The perched aquifer flows radially and away 

from beneath a playa lake designated Playa 1 (fig. 2) and 

ranges in thickness from less than 1 foot near its lateral extent 

to more than 50 feet near Playa 1.

The second water-yielding unit in the Ogallala Formation, 

below the fine-grained zone, is the Ogallala aquifer. The Ogallala aquifer is the primary source of drinking and irrigation 

water for most of the High Plains region in Texas. The Ogallala aquifer generally occurs at depths of approximately 350 

to 900 feet below LSD at the study site. Because of regional 

water-level declines, the upper 150 feet of the aquifer is mostly 

unsaturated. The water level is about 500 feet below LSD and 

the saturated part of the aquifer is about 1 to 100 feet thick in 

the southern part of the Pantex Plant site and about 250 to 400 

feet thick in the northern part. The primary flow direction in 

the Ogallala aquifer at the site is north to northeast. 

Acknowledgments

The authors thank Tony Biggs, B&W Pantex, for providing technical information on the wells; and Scott McLaughlin 

and Ken Nicholson, B&W Pantex, for their many hours 

setting and operating the pump for the pumping flowmeter 

measurements.
Introduction 3

Figure 1. Location of the Pantex Plant, Carson County, Texas.

Amarillo

Canyon

Claude

Panhandle

Borger

Lake

Meredith

PANTEX

PLANT

Texas Tech University Research Farm

PANTEX PLANT

Playa 1

Playa 2

Playa 3

Playa 4

Burning ground

Zone 11

Zone 12

Zone 10

Zone 4 

60

FM 2373

FM 683

FM 293

N 0 0.5 1 MILE

N

Area enlarged

Base from Babcock & Wilcox Technical Services Pantex, LLC

0 25 50 MILES
4 Analysis of Vertical Flow During Ambient and Pumped Conditions in Four Monitoring Wells at the Pantex Plant

Methods of Borehole Geophysical Data 

Collection

The USGS collected borehole geophysical data consisting of vertical flow rates, fluid resistivity/temperature, 

and natural gamma radiation in the four monitoring 

wells (PTX01–1012, PTX06–1044, PTX06–1056, and 

PTX06–1068) (fig. 2; table 1). These data were analyzed to 

determine the direction and magnitude of vertical flow in the 

screened intervals and distribution of transmissivity in the 

adjacent section of the aquifer. 

Pertinent information for monitoring wells (well identifier, location, altitude of LSD, total depth, depth to water, total 

screen length, and number of screened intervals) (table 1) 

was provided by B&W Pantex. In addition to the logs collected for this study, the Pantex monitoring wells were logged 

by a contractor at the time of drilling (B&W Pantex, writtten 

commun., 2008). Among the logs collected at that time 

were 16- and 64- inch normal resistivity, single-point 

resistance, spontaneous potential, and natural gamma in 

wells PTX01–1012, PTX06–1056, and PTX06–1068 and 

natural gamma and neutron in well PTX06–1044. Selected 

previously collected logs (normal resistivity and neutron) were 

digitized for use in this study because only photocopies of the 

logs were available. 

All geophysical probes used in the data collection for 

this study interfaced to a Century System VI log-acquisition 

system in the USGS Texas Water Science Center logging 

unit by way of 1⁄4-inch-diameter four-conductor wireline. The 

Figure 2. Ogallala aquifer monitoring wells logged with flowmeter at the Pantex Plant, Carson County, Texas.

Playa and identifier

Boundary of Department of Energy property

Ogallala aquifer monitoring well and Pantex well identifier

EXPLANATION

0 0.5 1 MILE Base from Babcock & Wilcox Technical Services Pantex, LLC

FM 293

FM 683

FM 2373

Playa 1

Playa 2

Playa 3

Burning ground

Zone 11

Zone 12

Zone 10

Zone 4 

Texas Tech University

Research Farm

N

PANTEX PLANT

PTX01–1012 PTX06–1068

PTX06–1044

PTX06–1056

Playa 1

PTX01–1012
Methods of Borehole Geophysical Data Collection 5

Table 1. Pertinent information for Ogallala aquifer monitoring wells logged at the Pantex Plant, Carson County, Texas, July–September 

2008.

USGS site 

identifier

Pantex well 

identifier

Location 

(latitude and

longitude 

in degrees, 

minutes, seconds)

Altitude of landsurface datum 

(feet above 

NAVD 88)

Total depth 

(feet below 

land-surface 

datum)

Static depth 

to water 

(feet below 

land-surface 

datum)

Total 

screen 

length 

(feet)

Number of 

screened 

intervals

352111101352301 PTX01–1012 N35 21 11.4 

W101 35 22.6

3,572 900 500 380 3

351944101324201 PTX06–1044 N35 19 44 

W101 32 42

3,555 613 475 180 2

351806101322901 PTX06–1056 N35 18 06 

W101 32 29 

3,489 475 393 120 1

352111101323401 PTX06–1068 N35 21 11 

W101 32 34

3,519 804 508 325 2

log-acquisition system was interfaced to a personal computer 

and data storage by way of an Ethernet connection. 

Vertical flow rates were measured under ambient and 

pumped flow conditions in the four monitoring wells. Unusually large drawdowns occurred at two monitoring wells 

(PTX06–1044 and PTX06–1056) while the wells were 

pumped at relatively low rates (about 1.5 gallons per minute 

[gal/min]), which might adversely affect the accuracy of the 

calculated transmissivity values. Accordingly, a decision was 

made to redevelop those wells using common methods such as 

scrubbing the screened interval with tubing-conveyed brushes 

to loosen fine-grained material in the filter pack and then surging the well to remove the loosened material. Logs were run 

again after redevelopment during ambient and pumped flow 

conditions in the two monitoring wells.

B&W Pantex furnished a 3-inch-diameter submersible 

pump capable of reaching the existing depths to water, which 

allowed for drawdown at a pumping rate of at least 5 gal/min. 

The submersible pump was deployed using a Smeal 5T pump 

hoist rig and 1.5-inch-diameter steel pipe. The pump and hoist 

rig was operated by B&W Pantex personnel.

Electromagnetic Flowmeter

The EM flowmeter measures the rate and direction of 

vertical flow in a borehole using the principle of Faraday’s 

Law of Induction. The EM flowmeter probe consists of an 

electromagnet and two electrodes 180 degrees apart and 90 

degrees to the magnetic field inside a hollow cylinder or tube. 

The voltage induced by a conductor moving at right angles 

through the magnetic field is directly proportional to the 

velocity of the conductor (water) through the field (Century 

Geophysical Corporation, 2006). 

Generally, when using the tool to measure low-velocity 

vertical flow in small-diameter wellbores, rubber diverters 

are installed around the sensor to direct the water flow 

through the open tube in the sensor. The diameter of the 

tube and voltage response is calibrated, and the volume of 

flow is instantaneously recorded. The direction of vertical 

water flow is determined by the polarity of the response 

with upward flow being positive and downward flow being 

negative. 

The flowmeter is placed in the wellbore with a rubber 

diverter installed to direct the flow through the sensor (fig. 3). 

Relatively high hydraulic head in a transmissive zone of the 

aquifer will push the flow from that high-head zone into the 

wellbore, through the tool in the direction of a transmissive 

zone of relatively low hydraulic head, to the low-head zone 

and out of the wellbore. 

Downward flow was calibrated at a rate of 1 gal/min 

and upward flow was calibrated at a pumped rate in the well, 

which was between 1.5 and 5 gal/min depending on the well 

and development status. Flowmeter log data were collected 

in stationary and trolling conditions for both ambient and 

pumped conditions. When possible, flowmeter data were collected at the same depths during both ambient and pumped 

flow conditions.

Fluid Resistivity/Temperature Logs

Fluid resistivity logs provide a record of the capacity of 

the borehole fluid to conduct electrical current (Keys, 1997). 

Changes in fluid resistivity are measured by ring electrodes 

inside a housing that allows borehole fluid to flow through it. 

The best fluid resistivity logging results are achieved when 

logging downward into boreholes containing ambient fluid 

that has had sufficient time to stabilize. Ideally, fluid resistivity 

logs are the first logs run to record ambient conditions before 

other probes have passed through the borehole and vertically 

mixed the borehole fluid. Curve deflections on the fluid resistivity log can indicate horizontal or vertical flow, stratification 

of borehole fluid, or screen openings in cased wells. Fluid 

resistivity values also can be used in calculations with other 

logs. 
6 Analysis of Vertical Flow During Ambient and Pumped Conditions in Four Monitoring Wells at the Pantex Plant

Figure 3. (A) Diagram of flowmeter in borehole showing zones of differing hydraulic head and direction of flow in the borehole, and (B) 

photograph of Century Model 9721 electromagnetic flowmeter with rubber diverter installed. 

 (A) (B)

Production

zone with

lower

hydraulic

head

Centralizer

Upward flow in

the borehole

Production

zone with

higher head

Diverter
Analysis of Vertical Flow 7

The fluid resistivity logs collected in this study were 

converted to fluid conductivity for comparison to specific 

conductance values of ground water in the area. The fluid 

conductivity values contained in the logs for this study are 

the values recorded in the ambient borehole temperature and 

are not corrected to a standard temperature. 

A Century model 8144c multiparameter probe was 

used to log fluid resistivity and temperature. Calibration 

of the fluid resistivity logging probes was done with solutions of known conductivity/resistivity in a two-point 

calibration. 

Natural Gamma Logs

Natural gamma logs provide a record of gamma radiation 

detected at depth in a borehole. Natural gamma radiation can 

be useful in determining lithologies and contact depths of the 

strata penetrated by the borehole. Fine-grained sediments that 

contain abundant clay tend to be more radioactive than quartzgrain sandstones or carbonates (Keys, 1997). The natural 

gamma log was run in conjunction with the fluid resistivity log 

and was recorded simultaneously in natural gamma counts per 

second. 

A natural gamma sensor with a sodium iodide detector 

built into the Century 8144c multiparameter probe was used. 

The natural gamma probe is calibrated at the factory and does 

not require calibration in the field. Natural gamma count rates, 

which commonly will increase in the proximity of clay and 

shale, could be slightly increased adjacent to any bentonite 

seals in the wells.

Analysis of Vertical Flow

Flowmeter and fluid resistivity/temperature data were 

analyzed by (1) plotting the logs with existing pertinent information such as other geophysical logs and casing and wellconstruction records provided by B&W Pantex, (2) evaluating 

the flowmeter data to identify potential zones of fluid movement to or from the wellbore and the magnitude and direction 

of vertical flow, (3) evaluating the flowmeter data with the 

USGS Flow–B numerical model (Paillet, 2000) to compute 

total transmissivity and distribution of transmissivity and head 

(as depth to water) in the screened intervals, and (4) plotting 

the transmissivity and head values on the logs. 

The Flow–B numerical model of Paillet (2000) is a 

computer program developed for analysis of flowmeter data. 

The model gives estimates of transmissivities and hydraulic 

heads of two or more water-producing (flow) zones intersecting a single interval of open borehole under typical field conditions. Zone transmissivity and hydraulic head are obtained 

by running the model in a series of iterations in which 

transmissivity and head values are adjusted by trial-and-error 

to develop a best-fit match between simulated and measured 

borehole flows. The output data from the numerical model are 

in appendix 1. 

Monitoring Well PTX01–1012

Monitoring well PTX01–1012 was constructed by 

Stewart Brothers Drilling Company near the northern Pantex 

Plant property boundary (fig. 2) on April 28, 2000. The well 

was drilled 7.9 inches in diameter to a total depth of 903 feet 

below LSD and constructed of schedule 10, 4-inch-diameter 

stainless steel casing and screened to 900 feet below LSD. The 

well has slotted screen openings of 0.010 inch in the following intervals: 460–640 feet, 660–720 feet, and 755–895 feet 

below LSD. Well records indicate that 8-16 sieve-size silica 

sand filter pack material is in the annular space of the screened 

intervals, and bentonite seal is in the annular space above each 

screened interval. Static water level (depth to water) was about 

500 feet below LSD on the day of logging.

Data Collected

The USGS collected EM flowmeter, fluid resistivity, 

temperature, and natural gamma measurements on August 

13, 2008. Flowmeter measurements were collected in trolling 

and stationary modes during ambient and pumped conditions. 

Thirty-six stationary measurements were collected during 

ambient conditions, and 32 stationary measurements were 

collected during pumped conditions. The well was logged during pumped conditions on the same day the well was logged 

during ambient conditions. The pump was set at about 520 feet 

below LSD and discharged about 5.5 gal/min at the surface, 

which created a constant drawdown of about 2 feet. 

Flow During Ambient and Pumped Conditions

Logs collected in monitoring well PTX01–1012 during 

ambient conditions (fig. 4) indicate a dynamic environment 

that probably was affected by pumping of nearby irrigation or 

public-supply wells. Downward flow ranging from 0.2 to 2.1 

gal/min indicates a lower hydraulic head in the interval below 

750 feet below LSD. The highest rate of ambient flow was 

measured at the stations in the casing between screened intervals (645–655 and 725–750 feet below LSD) that contained 

a bentonite seal in the annular space. The screened intervals 

below 650 feet below LSD are losing flow from the wellbore 

to the aquifer. In contrast, the screened interval above 650 feet 

below LSD appears to be gaining downward flow from the 

aquifer into the wellbore. This lower hydraulic head observed 

below 650 below LSD during ambient conditions probably is 

caused by nearby pumping. 

During pumping, downward vertical flow during ambient 

conditions was either reversed or reduced. At depths from 700 

to 850 feet below LSD, vertical flow that was downward during ambient conditions was reduced, and at depths from 575 to 
8 Analysis of Vertical Flow During Ambient and Pumped Conditions in Four Monitoring Wells at the Pantex Plant

Figure 4. Borehole geophysical logs plotted with calculated transmissivity and well construction in screened intervals of monitoring 

well PTX01–1012 at the Pantex Plant, Carson County, Texas. [LSD, land-surface datum; ft, feet; in, inches; diam., diameter; CPS, counts 

per second; Res., resistivity; OHM-M, ohm-meters; EMFM, electromagnetic flowmeter; gal/min, gallons per minute; Trans, transmissivity; 

Ft^2/D, feet squared per day; WL, depth to water from LSD; RES(FL), fluid resistivity; TEMP, temperature; DEG F, degrees Fahrenheit] 

352111101352301

Annular 

seals

PTX01–1012

35 deg. 21' 11.4"
Analysis of Vertical Flow 9

695 feet below LSD, downward ambient flow was reversed to 

upward as a result of the pumping. 

Ambient and pumped flowmeter values were entered into 

the Flow–B numerical model, as well as other data such as 

static water level, drawdown, and well diameter. The flowmeter values were plotted in Flow–B (appendix 1.1) and visually evaluated for fluctuations in the data that might indicate 

individual flow (production) zones. In well PTX01–1012, the 

flow zones were defined as originating below the following 

depths below LSD: 600, 650, 750, and 810 feet. Measurements at depths 650 and 750 feet below LSD correspond to 

cased intervals (hereinafter referred to as blanks) between the 

sealed screened intervals and show greater differences between 

ambient and pumped flowmeter values. Greater differences 

between ambient and pumped flowmeter values in the blanks 

probably are a result of a better seal of the flow diverter on the 

flowmeter to the smooth surface of the casing in the blank 

section and the bentonite seal in the annular space more 

efficiently funneling flow through the flowmeter sensor. The 

static depth to water for each of the production zones was 

computed: 

Zone 600–650 feet below LSD, 493 feet.

Zone 650–750 feet below LSD, 498 feet.

Zone 750–810 feet below LSD, 501 feet.

Zone 810–900 feet below LSD, 502 feet.

These calculated depths indicate hydraulic head was several 

feet lower in the lower two zones than the static head for the 

entire water column (500 feet below LSD), probably caused 

by nearby irrigation or public-supply well pumping at times 

during the flowmeter measurements.

During pumping, a gradual trend of more positive flowmeter values (upward flow) with distance up the well was 

observed from about 715 to 575 feet below LSD, with fluctuations at the blanks between sealed screened intervals (fig. 4; 

appendix 1.1). 

Estimated total transmissivity was calculated to be about 

3,100 feet squared per day (ft2

/d) and is distributed among the 

production zones as indicated: 

Zone 600–650 feet below LSD about 1 percent of 

the estimated transmissivity (31 ft2/d).

Zone 650–750 feet below LSD about 60 percent of 

the estimated transmissivity (1,860 ft2

/d). 

Zone 750–810 feet below LSD about 34 percent of 

the estimated transmissivity (1,054 ft2/d).

Zone 810–900 feet below LSD about 5 percent of 

the estimated transmissivity (155 ft2

/d).

The zone of highest transmissivity (650–750 feet below LSD) 

corresponds with a sand unit at about 650–715 below LSD 

with reduced gamma counts per second and increased resistivity, which indicate decreased clay content and greater sand 

content.

Monitoring Well PTX06–1044

Monitoring well PTX06–1044 was constructed by the 

Water Development Corporation near the eastern Pantex Plant 

property boundary (fig. 2) during August 13–27, 1999. The 

well was drilled 7.9 inches in diameter to a total depth of 

622 feet below LSD and constructed of schedule 10, 4-inchdiameter stainless steel casing and screened to 613 feet below 

LSD. The well has slotted screen openings of 0.020 inch in the 

following intervals: 393–493 and 533–613 feet below LSD. 

Well records indicate that 8-16 sieve-size silica sand filter pack 

material is in the annular space at 373–622 feet below LSD. 

Static water level was about 475 to 479 feet below LSD on the 

days of logging.

Data Collected

The USGS collected EM flowmeter, fluid resistivity, temperature, and natural gamma measurements on July 25, August 

11, and September 24, 2008. Ambient logs were collected 

July 25, 2008, and pumping logs were collected August 11, 

2008, because muddy conditions delayed access to the well. 

Ambient measurements were rechecked on August 11, 2008, 

to confirm ambient conditions had not changed. Flowmeter 

measurements were collected in trolling and stationary modes 

during ambient and pumped conditions. Fourteen stationary 

measurements were collected during ambient conditions on 

July 25, 2008, and 11 stationary measurements were collected 

while pumping 1.5 gal/min on August 11, 2008. 

The pump was set at about 511 feet below LSD. The 

unusually low well yield of 1.5 gal/min resulted in 30 feet of 

drawdown. To improve well yield and reduce drawdown, the 

well screens were cleaned, and the well was redeveloped by 

B&W Pantex and subsequently logged again by the USGS 

with an EM flowmeter on September 24, 2008. After redevelopment, the pump was set at about 500 feet below LSD. 

Thirteen stationary measurements were collected during 

ambient conditions, and 11 stationary measurements were 

collected while pumping 5 gal/min. The drawdown observed 

while pumping 5 gal/min after redevelopment was about 17 

feet, considerably less than the 30 feet of drawdown before 

redevelopment while pumping 1.5 gal/min. 

Flow During Ambient and Pumped Flow 

Conditions Before Redevelopment

Logs collected in monitoring well PTX06–1044 July 25, 

2008, during ambient conditions (fig. 5) before redevelopment indicate a static environment with no flow. This lack 

of flow during ambient conditions indicates generally uniform hydraulic heads throughout the screened intervals; 

however in this case, results obtained after redevelopment 

indicate that screened intervals were not allowing adequate 

flow to enter the wellbore during ambient conditions before 

redevelopment. 
10 Analysis of Vertical Flow During Ambient and Pumped Conditions in Four Monitoring Wells at the Pantex Plant

Figure 5. Borehole geophysical logs plotted with calculated transmissivity and well construction in screened intervals of monitoring 

well PTX06–1044 at the Pantex Plant, Carson County, Texas. [LSD, land-surface datum; ft, feet; in, inches; diam., diameter; CPS, counts 

per second; EMFM, electromagnetic flowmeter; Amb, ambient; Before, before redevelopment; Gal/min (gpm), gallons per minute; Pu, 

pumping; After, after redevelopment; WL, depth to water from LSD; Trans, transmissivity; Ft^2/D, feet squared per day; RES(FL), fluid 

resistivity; OHM-M, ohm-meters; TEMP, temperature; DEG F, degrees Fahrenheit]

Altitude of log datum (ft above NAVD of 1988) 3539.11

Casing depth (ft) 613

Log datum LSD

Well name PTX06–1044

County Carson

Borehole bit size (in) 7.865

Borehole depth (ft) 622

Casing diam. (in) 4

Latitude N 35 deg. 19' 44"

Date of log 7/25,8/11,9/24/08

Owner Pantex Site ID 351944101324201

State Texas

Longitude W 101 deg. 32' 42"

Depth EMFM Amb Before Construction

-5 Gal/Min 5

Neutron

0 CPS 50

Natural Gamma

0 CPS 150

RES(FL) Amb Before

15 OHM-M 20

EMFM Pu Before

-5 Gal/Min 5

WL Depth Before

500 tF 054

WL Depth After

500 tF 054

Trans. Before

0.5 Ft^2/D 500

TEMP Amb. Before

63 DEG F 73

TEMP Pu Before

63 DEG F 73

RES(FL) Pu Before

15 OHM-M 20

EMFM Amb After

-5 Gal/Min 5

Trans. After

0.5 Ft^2/D 500

Static WL

0 1

EMFM Pu After

-5 gpm 5

TEMP Amb After

63 DEG F 73

RES(FL) Amb. After

15 OHM-M 20

RES(FL) Pu After

15 OHM-M 20

400

450

500

550

600

473

482

481

481

481

473

9/24/08
Analysis of Vertical Flow 11

During pumping there was upward vertical flow at rates 

ranging from 0.1 to about 1.5 gal/min. Upward vertical flow 

occurred at 590 to 542 below LSD, with most of the flow 

entering the well at depths below 570 feet below LSD. 

Ambient and pumped flowmeter values were entered 

into the Flow–B numerical model, as well as other data such 

as static water level, drawdown, and well diameter. The 

flowmeter values were plotted in Flow–B (appendix 1.2) 

and visually evaluated for fluctuations in the data that might 

indicate individual flow zones. To discretize the numerical 

model with consistent flow zones, the flowmeter logs collected 

after redevelopment were ultimately used for the selection of 

flow zones, which facilitated a detailed analysis of the flow 

distribution. The flow zones were defined as originating below 

the following depths below LSD: 495, 530, 555, 570, and 590 

feet. The depth to static water level for each zone was about 

475 feet below LSD, about the same as depth to the static 

water level for the entire water column (475–479 feet below 

LSD).

During pumping, a gradual trend of more positive 

flowmeter values (upward flow) with distance up the well 

was observed from about 590 to 542 feet below LSD (fig. 5; 

appendix 1.2). 

Estimated total transmissivity before redevelopment was 

calculated to be about 95 ft2

/d and is distributed among the 

production zones as indicated: 

Zone 495–530 feet below LSD none of the estimated 

transmissivity. 

Zone 530–555 feet below LSD about 0.5 percent of 

the estimated transmissivity (less than 1 ft2/d). 

Zone 555–570 feet below LSD about 2 percent of 

the estimated transmissivity (2 ft2/d). 

Zone 570–590 feet below LSD about 92.5 percent of the 

estimated transmissivity (88 ft2/d). 

Zone 590–609 feet below LSD about 5 percent of the 

estimated transmissivity (5 ft2/d). 

The zone of highest transmissivity (570–590 feet 

below LSD) corresponds with a sand unit 577–603 feet 

below LSD. However, these transmissivity values are considered to be in error because of the lack of communication 

between the well and the aquifer before redevelopment. The 

hydraulic properties listed here are for documentation of 

results only.

Flow During Ambient and Pumped Flow 

Conditions After Redevelopment

Logs collected in monitoring well PTX06–1044 during 

ambient conditions after redevelopment September 24, 2008 

(fig. 5; appendix 1.3), indicate a near-static environment with 

minimal downward flow (-0.17 gal/min) from about 495 to 

530 feet below LSD. This very low downward flow during 

ambient conditions indicates lower hydraulic head (compared 

to static water level) at the bottom of the zone (530 feet below 

LSD). No flow is apparent elsewhere in the well, indicating 

essentially uniform hydraulic head throughout the screened 

intervals; however, the lower hydraulic head at 530 feet below 

LSD must be maintained to the bottommost zone of production to prevent upward flow from occurring. 

During pumping there was upward vertical flow at rates 

ranging from 0.5 to about 4.8 gal/min. Upward vertical flow 

occurred at 590 to 514 feet below LSD, with most of the flow 

entering the well at depths between 529 and 539 feet below 

LSD. 

Ambient and pumped flowmeter values were entered into 

the Flow–B numerical model (appendix 1.3), as well as other 

data such as static water level, drawdown, and well diameter, as before redevelopment. The flow zones defined were 

the same as those defined before redevelopment, originating 

below the following depths below LSD: 495, 530, 555, 570, 

and 590 feet. The static depth to water for each of the production zones was computed: 

Zone 495–530 feet below LSD, 473 feet.

Zone 530–555 feet below LSD, 482 feet.

Zone 555–570 feet below LSD, 481 feet.

Zone 570–590 feet below LSD, 481 feet.

Zone 590–609 feet below LSD, 481 feet.

These calculated depths indicate hydraulic head was 8 to 9 feet 

lower in the zones of production from 530 to 609 feet below 

LSD than the hydraulic head for the entire water column, 

probably caused by nearby wells pumping at times during the 

flowmeter measurements.

During pumping, a gradual trend of more positive flowmeter values (upward flow of 0.5 to 2.4 gal/min) with distance 

up the well was observed from about 590 to 540 feet below 

LSD. A large increase in upward flow occurred between 540 

and 530 feet below LSD indicating the most productive zone 

between those depths (fig. 5; appendix 1.3). 

Estimated total transmissivity after redevelopment was 

calculated to be about 520 ft2

/d and is distributed among the 

production zones as indicated: 

Zone 495–530 feet below LSD less than 1 percent of 

the estimated transmissivity (1 ft2/d). 

Zone 530–555 feet below LSD about 93.5 percent of 

the estimated transmissivity (486 ft2/d).

Zone 555–570 feet below LSD about 2 percent of 

the estimated transmissivity (10 ft2/d).

Zone 570–590 feet below LSD about 3 percent of 

the estimated transmissivity (16 ft2

/d).

Zone 590–609 feet below LSD about 1 percent of 

the estimated transmissivity (7 ft2

/d). 
12 Analysis of Vertical Flow During Ambient and Pumped Conditions in Four Monitoring Wells at the Pantex Plant

Figure 6. Borehole geophysical logs plotted with calculated transmissivity and well construction in screened interval of monitoring 

well PTX06–1056 at the Pantex Plant, Carson County, Texas. [LSD, land-surface datum; ft, feet; in, inches; diam., diameter; CPS, counts 

per second; Res., resistivity; OHM-M, ohm-meters; EMFM, electromagnetic flowmeter; Amb, ambient; Before, before redevelopment; 

gal/min, gallons per minute; Pu, pumping; After, after redevelopment; WL, depth to water from LSD; Trans, transmissivity; Ft^2/D, 

feet squared per day; Fl. Cond., fluid conductivity at well; uS/cm, microsiemens per centimeter; Temp, temperature; DEG F, degrees 

Fahrenheit] 

Casing depth (ft) 475

Altitude of log datum (ft above NAVD of 1988) 3530.8

Well name PTX06–1056

Log datum LSD

Borehole bit size (in) 7.865

County CARSON

Casing diam. (in) 4

Borehole depth (ft) 500

Latitude N 35 deg.18' 06"

Date of log 7/23, 8/14, 9/23-24/08

Site ID 351806101322901

State Texas

Owner Pantex

Longitude W 101 deg. 32' 29"

Depth Natural Gamma

0 CPS 150

Temp. Amb. Before

63 DEG F 78

Fl.Cond. Amb.Before

300 uS/cm 500

Short Normal Res.

0 OHM-M 200

Long Normal Res.

0 OHM-M 200

EMFM Amb Before

-2 gal/min 2

WL Depth Before

450 350Ft

WL Depth After

450 350Ft

Trans. Before

0.5 Ft^2/D 500

Construction

EMFM Pu Before

-3 gal/min 3

EMFM Pu After

-3 gal/min 3

EMFM Amb After

-3 gal/min 3

Fl. Cond. Amb. After

300 uS/cm 500

Temp. Amb. After

63 DEG F 78

Trans After

0.5 Ft^2/D 500

Static WL

0 1

300

350

400

450

500

395

395

395

393

401

9/23/08
Analysis of Vertical Flow 13

The zone of highest transmissivity (530–555 feet below 

LSD) corresponds with a thin sand unit with somewhat 

higher natural gamma counts, which indicates moderate 

clay content, less sand content, and likely lower permeability 

than other units. The noted increase in flow entering the 

well at depths between 529 and 539 feet below LSD (fig. 5) 

could be attributed to the blank section of casing improving 

the seal of the flowmeter diverter thus forcing more fluid to 

enter the sensor in that range. If this is the case, the large 

computed percentage of flow in the zone 530–555 feet below 

LSD likely is more indicative of the transmissivity of the 

entire lower screened section below 530 feet below LSD. 

Monitoring Well PTX06–1056

Monitoring well PTX06–1056 was constructed by 

Stewart Brothers Drilling Company near the southeastern 

corner of the Pantex Plant property boundary (fig. 2) on May 

15, 2000. The well was drilled 7.9 inches in diameter to a total 

depth of 500 feet below LSD and constructed of schedule 10, 

4-inch-diameter stainless steel casing and screened to 475 feet 

below LSD. The well has slotted screen openings of 0.020 

inch in the interval 350–470 feet below LSD. Well records 

indicate that 8-16 sieve-size silica sand filter pack material is 

in the annular space at 328–622 feet below LSD. Static water 

level was about 392 to 393 feet below LSD on the days of 

logging.

Data Collected

The USGS collected EM flowmeter, fluid resistivity, temperature, and natural gamma measurements on July 23, August 

14, and September 23–24, 2008. Ambient logs were collected 

July 23, 2008, and pumping logs were collected August 14, 

2008, because muddy conditions delayed access to the well. 

Ambient measurements were rechecked on August 14, 2008, 

to confirm ambient conditions had not changed. Flowmeter 

measurements were collected in trolling and stationary modes 

during ambient and pumped conditions. Sixteen stationary 

measurements were collected during ambient conditions on 

July 23, 2008, and 11 stationary measurements were collected 

while pumping 1.5 gal/min on August 14, 2008 (fig. 6; appendix 1.4;). 

The pump was set at about 403 feet below LSD. The 

unusually low well yield of 1.5 gal/min resulted in a constant drawdown of about 7.6 feet. To improve well yield and 

reduce drawdown, the well screen was cleaned, and the well 

was redeveloped by B&W Pantex and subsequently logged 

again by the USGS with an EM flowmeter on September 23, 

2008. After redevelopment, the pump was set at about 412 feet 

below LSD. Sixteen stationary measurements were collected 

during ambient conditions, and 12 stationary measurements 

were collected while pumping 3 gal/min (fig. 6; appendix 

1.5). The drawdown observed while pumping 3 gal/min after 

redevelopment was about 13.5 feet, substantially larger than 

the 7.6 feet of drawdown before redevelopment while pumping 1.5 gal/min. 

Flow During Ambient and Pumped Flow 

Conditions Before Redevelopment

Logs collected in monitoring well PTX06–1056 during ambient conditions before redevelopment July 23, 2008 

(fig. 6), indicate a static environment with no flow. The lack 

of flow during ambient conditions generally indicates uniform 

hydraulic heads throughout the screened interval. 

During pumping there was upward vertical flow at rates 

ranging from 0.3 to about 1.5 gal/min. Upward vertical flow 

occurred at 423 to 456 below LSD, with most of the flow 

entering the well at depths below 450 feet below LSD. 

Ambient and pumped flowmeter values were entered 

into the Flow–B numerical model, as well as other data such 

as static water level, drawdown, and well diameter. The 

flowmeter values were plotted in Flow–B (appendix 1.4) and 

were visually evaluated for fluctuations that might indicate 

individual flow zones. To discretize the numerical model 

with consistent flow zones, the flowmeter logs collected after 

redevelopment were ultimately used for the selection of flow 

zones, which facilitated a detailed analysis of the flow distribution. The flow zones were defined as originating below the 

following depths below LSD: 415, 431, 453, and 460 feet. The 

static depths to water for the production zones were the same 

as the static depth to water for the entire water column (about 

392 feet below LSD).

During pumping, a gradual trend of more positive 

flowmeter values (upward flow) with distance up the well 

was observed from about 455 to 432 feet below LSD. The 

upward flow results from an apparent increase in flow below 

450 feet below LSD and remains relatively constant through 

the uppermost measurement at 423 feet below LSD (fig. 6; 

appendix 1.4). Increased upward flows are observed at 431 

and 451 feet below LSD, depths in the well that could correspond to decreased inside diameter at the threaded connections 

of screen sections, which likely improve the diverter seal on 

the flowmeter sensor to the casing. 

Estimated total transmissivity before redevelopment was 

calculated to be about 450 ft2

/d and is distributed among the 

production zones as indicated: 

Zone 415–431 feet below LSD none of the estimated 

transmissivity. 

Zone 431–453 feet below LSD about 2.5 percent of 

the estimated transmissivity (13 ft2

/d). 

Zone 453–460 feet below LSD about 95 percent of 

the estimated transmissivity (427 ft2

/d). 

Zone 460–466 feet below LSD about 2.5 percent of 

the estimated transmissivity (13 ft2/d). 

The zone of highest transmissivity (453–460 feet below LSD) 

corresponds with a sand unit 443–460 feet below LSD with 
14 Analysis of Vertical Flow During Ambient and Pumped Conditions in Four Monitoring Wells at the Pantex Plant

Figure 7. Borehole geophysical logs plotted with calculated transmissivity and well construction in screened interval of monitoring 

well PTX06–1068 at the Pantex Plant, Carson County, Texas. [LDS, land-surface datum; ft, feet; in, inches; diam., diameter; CPS, counts 

per second; Res., resistivity; OHM-M, ohm-meters; EMFM, electromagnetic flowmeter; gal/min, gallons per minute; Trans, transmissivity; 

Ft^2/D, feet squared per day; WL, depth to water from LSD; Fl. Cond., fluid conductivity at well temperature; uS/cm, microsiemens per 

centimeter; TEMP, temperature; DEG F, degrees Fahrenheit]

Altitude of log datum (ft above NAVD of 1988) 3533.88

Casing depth (ft) 804

Log datum LSD

Well name PTX06–1068

County Carson

Borehole bit size (in) 8

Borehole depth (ft) 805

Casing diam. (in) 4

Latitude N 35 deg. 21' 11"

Date of log 7/23, 8/12/08

Owner Pantex Site ID 352111101323401

State Texas

Longitude W 101 deg. 32' 34"

Depth Natural Gamma

0 CPS 150

TEMP Ambient

63 DEG F 73

Fl. Cond. Ambient

500 uS/cm 700

Short Normal Res.

0 OHM-M 200

Long Normal Res.

0 OHM-M 200

Trans Construction

0.5 Ft^2/D 500

Water Level Depth

400 550Ft

Static WL

0 1

EMFM Ambient

-5 gal/min 5

EMFM Pumping

-5 gal/min 5

400

500

600

700

800

508

508

508

508

Annular 

seals

8/12/08
Analysis of Vertical Flow 15

somewhat decreased natural gamma counts (fig. 6), which 

indicates less clay content and more sand content. 

Flow During Ambient and Pumped Flow 

Conditions After Redevelopment

Logs collected in monitoring well PTX06–1056 during 

ambient conditions after redevelopment September 23, 2008 

(fig. 6; appendix 1.5), indicate a near-static environment with 

no flow from about 401 to 456 feet below LSD. This lack of 

flow during ambient conditions indicates generally uniform 

hydraulic heads throughout the section of screened interval 

above 456 feet below LSD. A very small amount of downward 

flow occurred during ambient conditions at 461 feet below 

LSD, which indicates lower hydraulic head at the bottom of 

the zone (466 feet below LSD). 

During pumping there was upward vertical flow at rates 

ranging from 0.7 to about 2.9 gal/min. Upward vertical flow 

occurred at 456 to 423 below LSD, with most of the flow 

entering the well at depths between 456 and 451 feet below 

LSD. 

Ambient and pumped flowmeter values were entered into 

the Flow–B numerical model (appendix 1.5), as well as other 

data such as static water level, drawdown, and well diameter, 

as before redevelopment. The flow zones were defined as 

originating below the following depths below LSD: 415, 431, 

453, 460, and 466 feet. The static depth to water for each of 

the production zones was computed: 

Zone 415–431 feet below LSD, 395 feet.

Zone 431–453 feet below LSD, 395 feet.

Zone 453–460 feet below LSD, 395 feet.

Zone 460–466 feet below LSD, 393 feet.

Zone 466–475 feet below LSD, 401 feet.

These calculated depths indicate a 2- to 3-foot decrease 

in hydraulic head in the zones 415–460 feet below LSD 

and about an 8-foot decrease in hydraulic head in the zone 

466–475 feet below LSD relative to the hydraulic head for the 

entire water column (392–393 feet below LSD). Similar to the 

other wells, the head decreases likely are caused by nearby 

irrigation or supply wells pumping during the flowmeter measurements.

During pumping, a sharp increase in positive flowmeter values (upward flow) ranging from 0.7 to 1.85 gal/min 

occurred from about 456 to 451 feet below LSD and indicates 

a zone of dominant inflow. This upward flow continues up the 

well, decreases in magnitude somewhat from 446 to 436 feet 

below LSD, then increases again between 436 and 431 feet 

below LSD indicating another productive zone between those 

depths (fig. 6; appendix 1.5). 

Estimated total transmissivity after redevelopment was 

calculated to be about 330 ft2

/d—slightly lower than before 

redevelopment (450 ft2/d)—and is distributed among the production zones as indicated: 

Zone 415–431 feet below LSD about 1 percent of 

the estimated transmissivity (3 ft2/d).

Zone 431–453 feet below LSD about 15 percent of 

the estimated transmissivity (50 ft2/d).

Zone 453–460 feet below LSD about 80 percent of 

the estimated transmissivity (264 ft2/d).

Zone 460–466 feet below LSD about 3 percent of 

the estimated transmissivity (10 ft2/d).

Zone 466–475 feet below LSD about 1 percent of 

the estimated transmissivity (3 ft2/d).

The zone of highest transmissivity (453–460 feet below LSD) 

corresponds with a sand unit 443–460 feet below LSD with 

somewhat decreased natural gamma counts (fig. 6), which 

indicates less clay content and more sand content. Redevelopment resulted in the percentage of total transmissivity 

accounted for by this zone to decrease from 95 to 85 percent. 

The percentage of transmissivity of the zone accounting for 

the second-highest percentage of transmissivity (431–453 

feet below LSD) increased from about 2.5 percent of the 

total transmissivity (about 13 ft2

/d) before redevelopment to 

about 15 percent of the total transmissivity (about 50 ft2/d) 

after redevelopment. This redistribution of transmissivity is 

related not only to the redevelopment but also to the amount 

of stress on the well. Drawdown in this well increased from 

7.6 feet while pumping at 1.5 gal/min before redevelopment 

to 13.5 feet while pumping at 3 gal/min. The larger pumping 

stress caused a redistribution of flow that resulted in more 

drawdown, which caused the model to calculate a lower total 

transmissivity. 

Monitoring Well PTX06–1068

Monitoring well PTX06–1068 was constructed by 

Layne Christensen near the northeastern corner of the Pantex 

property boundary (fig. 2) during May 1–5, 2001. The well 

was drilled 8 inches in diameter to a total depth of 805 feet 

below LSD and constructed of schedule 10, 4-inch diameter 

stainless steel casing and screened to 804 feet below LSD. 

The well has slotted screen openings of 0.010 inch in the 

following intervals: 454–754 and 774–799 feet below LSD. 

Well records indicate that 10-20 sieve-size silica sand filter 

pack material is in the annular space of the screened intervals, 

and bentonite seal is in the annular space above each screened 

interval. Static water level was about 508 feet below LSD on 

the days of logging.

Data Collected

The USGS collected EM flowmeter, fluid resistivity, 

temperature, and natural gamma measurements on July 23 

and August 12, 2008. Flowmeter measurements were collected in trolling and stationary modes during ambient and 
16 Analysis of Vertical Flow During Ambient and Pumped Conditions in Four Monitoring Wells at the Pantex Plant

pumped conditions. Thirty stationary measurements were 

collected during ambient conditions, and 27 stationary measurements were collected during pumped conditions. The well 

was logged during pumped conditions on August 12, 2008, 

because muddy conditions delayed access to the well. The 

pump was set at about 531 feet below LSD and discharged 

about 4.5 gal/min at the surface, which created a constant 

drawdown of about 10 feet. 

Flow During Ambient and Pumped Conditions

Logs collected in monitoring well PTX06–1068 on July 

23, 2008, during ambient conditions indicate a static environment with no flow (fig. 7; appendix 1.6). The lack of flow during ambient conditions indicates generally uniform hydraulic 

heads throughout the screened interval with no influence from 

nearby pumping wells. 

During pumping there was upward vertical flow at 

rates ranging from 0.4 to 4.8 gal/min. Ambient and pumped 

flowmeter values were entered into the Flow–B numerical 

model, as well as other data such as static water level, drawdown, and well diameter. The flowmeter values were plotted 

in Flow–B (appendix 1.6) and were visually evaluated for 

fluctuations in the data that might indicate individual flow 

zones. In this well, the flow zones were defined as originating 

below the following depths below LSD: 565, 650, 775, and 

789 feet. Measurements at depths of 775 and 789 feet below 

LSD correspond to measurements collected at blank intervals 

at the threaded parts of screened intervals and show the greatest relative difference between ambient and pumped flowmeter 

values. This is probably a result of a better seal of the flow 

diverter on the flowmeter to the smooth surface of the casing 

blank section and more efficient funneling of flow through the 

flowmeter sensor. The static depths to water for the production zones were the same as static depth to water for the entire 

water column (about 508 feet below LSD). 

During pumping, a gradual trend of more positive flowmeter values (upward flow) with distance up the well was 

observed from about 789 to 765 feet below LSD, with the 

highest values at the blanks between sealed screened intervals 

(fig. 7; appendix 1.6). Flowmeter values between 555 and 655 

feet below LSD appear to alternate between relatively high 

and low flow values with highest values every 20 feet. This 

likely is an artifact of well construction. The screen sections 

have a threaded connection every 20 feet, and there is a better 

seal with the diverter in the threaded (smaller diameter) part of 

the screen sections. The higher flowmeter values were used in 

the numerical model. 

Estimated total transmissivity was calculated to be about 

200 ft2

/d and is evenly distributed among the production zones 

as indicated: 

Zone 565–650 feet below LSD about 25 percent of 

the estimated transmissivity (50 ft2/d).

Zone 650–775 feet below LSD about 25 percent of 

the estimated transmissivity (50 ft2/d).

Zone 775–789 feet below LSD about 25 percent of 

the estimated transmissivity (50 ft2

/d).

Zone 789–804 feet below LSD about 25 percent of 

the estimated transmissivity (50 ft2/d).

Summary

The Pantex Plant is a U.S. Department of Energy/

National Nuclear Security Administration (USDOE/NNSA)-

owned, contractor-operated facility managed by Babcock & 

Wilcox Technical Services Pantex, LLC (B&W Pantex) in 

Carson County, Tex., approximately 17 miles northeast of 

Amarillo. The U.S. Geological Survey (USGS), in cooperation 

with B&W Pantex through the USDOE/NNSA, made a series 

of flowmeter measurements and collected other borehole geophysical logs during July–September 2008 to analyze vertical 

flow in screened intervals of four selected monitoring wells at 

the Pantex Plant. Hydraulic properties (transmissivity values) 

of the section of High Plains (Ogallala) aquifer penetrated by 

the wells also were computed. 

The USGS collected borehole geophysical data consisting 

of vertical flow rates, fluid resistivity/temperature, and natural 

gamma radiation in the four monitoring wells (PTX01–1012, 

PTX06–1044, PTX06–1056, and PTX06–1068). Vertical 

flow rates were measured under ambient and pumped flow 

conditions in the four monitoring wells. Unusually large 

drawdowns occurred at two monitoring wells (PTX06–1044 

and PTX06–1056) while the wells were pumped at relatively 

low rates (about 1.5 gal/min), which might adversely affect the 

accuracy of the calculated transmissivity values. Accordingly, 

a decision was made to redevelop those wells. Logs were run 

again after redevelopment during ambient and pumped flow 

conditions in the two monitoring wells.

Flowmeter and fluid resistivity/temperature data were 

analyzed by (1) plotting the logs with existing pertinent 

information such as other geophysical logs and casing 

and well-construction records provided by B&W Pantex, 

(2) evaluating the flowmeter data to identify potential zones 

of fluid movement to or from the wellbore and the magnitude 

and direction of vertical flow, (3) evaluating the flowmeter 

data with the USGS Flow–B numerical model to compute 

total transmissivity and distribution of transmissivity and 

head (as depth to water) in the screened intervals, and 

(4) plotting the transmissivity and head values on the logs. 

Logs collected in monitoring well PTX01–1012 during 

ambient conditions indicate a dynamic environment that 

probably was affected by pumping of nearby irrigation or 

public-supply wells. Downward flow ranged from 0.2 to 

2.1 gal/min. During pumping, downward vertical flow that 

occurred during ambient conditions was either reversed or 

reduced. The flow (production) zones in the well were defined 

from Flow–B numerical model results as originating below 

the following depths below LSD: 600, 650, 750, and 810 feet. 

During pumping, a gradual trend of more positive flowmeter 
Summary 17

values (upward flow) with distance up the well was observed 

from about 715 to 575 feet below LSD. Estimated total 

transmissivity for the four identified production zones taken 

together was calculated to be about 3,100 ft2/d. The zone of 

highest transmissivity (1,860 ft2/d) corresponds with a sand 

unit at about 650–715 below LSD. 

Logs collected in monitoring well PTX06–1044 during 

ambient conditions before redevelopment indicate a static 

environment with no flow. During pumping there was 

upward vertical flow at rates ranging from 0.1 to about 

1.5 gal/min. The flow zones in the well were defined from 

Flow–B numerical model results as originating below the following depths below LSD: 495, 530, 555, 570, and 590 feet. 

During pumping, a gradual trend of more positive flowmeter 

values (upward flow) with distance up the well was observed 

from about 590 to 542 feet below LSD. Estimated total transmissivity before redevelopment for the five identified production zones taken together was calculated to be about 95 ft2

/d; 

but this and associated transmissivity values for the individual 

zones are considered to be in error because of the lack of 

communication between the well and the aquifer before 

redevelopment. 

Logs collected in monitoring well PTX06–1044 during 

ambient conditions after redevelopment indicate a near-static 

environment with minimal downward flow (-0.17 gal/min). 

During pumping there was upward vertical flow at rates ranging from 0.5 to about 4.8 gal/min. The flow zones defined 

from Flow–B numerical model results were the same as those 

defined before redevelopment. During pumping, a gradual 

trend of more positive flowmeter values (upward flow of 0.5 

to 2.4 gal/min) with distance up the well was observed from 

about 590 to 540 feet below LSD. A large increase in upward 

flow occurred between 540 and 530 feet below LSD indicating the most productive zone between those depths. Estimated 

total transmissivity after redevelopment for the five identified 

production zones taken together was calculated to be about 

520 ft2

/d. The zone of highest transmissivity (486 ft2/d) corresponds with a thin sand unit. 

Logs collected in monitoring well PTX06–1056 during 

ambient conditions before redevelopment indicate a static 

environment with no flow. During pumping there was upward 

vertical flow at rates ranging from 0.3 to about 1.5 gal/min. 

The flow zones in the well were defined from Flow–B numerical model results as originating below the following depths 

below LSD: 415, 431, 453, and 460 feet. During pumping, a 

gradual trend of more positive flowmeter values (upward flow) 

with distance up the well was observed from about 455 to 432 

feet below LSD. Estimated total transmissivity before redevelopment for the four identified production zones taken together 

was calculated to be about 450 ft2

/d. The zone of highest transmissivity (427 ft2

/d) corresponds with a sand unit 443–460 feet 

below LSD. 

Logs collected in monitoring well PTX06–1056 during ambient conditions after redevelopment indicate a 

near-static environment with no flow from about 401 to 

456 feet below LSD. A very small amount of downward 

flow occurred during ambient conditions at 461 feet below 

LSD. During pumping there was upward vertical flow at 

rates ranging from 0.7 to about 2.9 gal/min. The flow zones 

in the well were defined from Flow–B numerical model 

results as originating below the following depths below 

LSD: 415, 431, 453, 460, and 466 feet. During pumping, 

a sharp increase in positive flowmeter values (upward flow) 

ranging from 0.7 to 1.85 gal/min occurred from about 456 to 

451 feet below LSD and indicates a zone of dominant inflow. 

Estimated total transmissivity after redevelopment for the five 

identified production zones taken together was calculated to be 

about 330 ft2

/d. The zone of highest transmissivity (264 ft2/d) 

corresponds with a sand unit 443–460 feet below LSD. 

Logs collected in monitoring well PTX06–1068 during 

ambient conditions indicate a static environment with no 

flow. During pumping there was upward vertical flow at 

rates ranging from 0.4 to 4.8 gal/min. The flow zones in 

the well were defined from Flow–B numerical model results 

as originating below the following depths below LSD: 565, 

650, 775, and 789 feet. During pumping, a gradual trend of 

more positive flowmeter values (upward flow) with distance 

up the well was observed from about 789 to 765 feet below 

LSD. Estimated total transmissivity for the four identified 

production zones taken together was calculated to be about 

200 ft2

/d and is evenly distributed among the selected 

zones.

References

Century Geophysical Corporation, 2006, 9721 Logging 

tool—E-M flowmeter: accessed December 22, 2008, at 

http://www.century-geo.com/9721-index.html

Holliday, V.T., 1989, The Blackwater Draw Formation 

(Quaternary)—A 1.4-plus-m.y. record of eolian sedimentation and soil formation of the southern High Plains: Geological Society of America Bulletin 101, p. 1,598–1,607.

Keys, W.S., 1997, A practical guide to borehole geophysics in 

environmental investigations: Boca Raton, Fla., CRC-Lewis 

Publishers, 176 p. 

Paillet, F.L., 2000, A field technique for estimating aquifer 

parameters using flow log data: Ground Water, v. 38, no. 4, 

p. 510–521.

U.S. Department of Energy, 2009, Pantex info—General 

overview: National Nuclear Security Administration Pantex 

Plant, accessed January 14, 2009, at http//:www.pantex.com/

ucm/groups/exweb/@exweb/@pr/documents/web_content/

ex_doc_gen_ovrview.pdf
Blank Page
Appendix 1—Flowmeter Analyses of Monitoring Wells With 

Flow–B Numerical Model Input and Results

Appendix 1
Blank Page
Appendix 1 211.1. Monitoring Well PTX01–1012
22 Analysis of Vertical Flow During Ambient and Pumped Conditions in Four Monitoring Wells at the Pantex Plant

1.2. Monitoring Well PTX06–1044 Before Redevelopment
Appendix 1 231.3. Monitoring Well PTX06–1044 After Redevelopment
24 Analysis of Vertical Flow During Ambient and Pumped Conditions in Four Monitoring Wells at the Pantex Plant

1.4. Monitoring Well PTX06–1056 Before Redevelopment
Appendix 1 251.5. Monitoring Well PTX06–1056 After Redevelopment
26 Analysis of Vertical Flow During Ambient and Pumped Conditions in Four Monitoring Wells at the Pantex Plant

1.6. Monitoring Well PTX06–1068
Publishing support provided by

Lafayette Publishing Service Center

Information regarding water resources in Texas is available at 

http://tx.usgs.gov/
Stanton, Thomas, and Stovall—Analysis of Vertical Flow During Ambient and Pumped Conditions in Four Monitoring Wells at the Pantex Plant, Texas—OFR 2009–1017

Printed on recycled paper