Bureau of Mines Report of Investigations/l978 

Improved Methods for Monitoring 

Production From Vertical 

Degasification Wells 

@ UNITED STATES DEPARTMENT OF THE INTERIOR 
Report of Investigations 8309 

Improved Methods for Monitoring 

Production From Vertical 

Degasification Wells 

By S. W. Lambert and M. A. Trevits 

UNITED STATES DEPARTMENT OF THE INTERIOR 

Cecil D. Andrus, Secretary 

BUREAU OF MINES 
CONTENTS 

Page 

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

Introduction ............................................................. 1 

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

General well completion .................................................. 2 

Methods of removing and measuring water .................................. 2 

Problems of monitoring water production .............................. 2 

Solids in waterlines ................................................ 4 

Freezing ............................................................ 4 

Improper pumping interval ........................................... 4 

Gas in waterlines ................................................... 5 

Improved methods for monitoring water production ......................... 5 

Methods of removing and measuring gas .................................... 8 

Problems of monitoring gas production .................................... 9 

Water in gaslines ................................................... 9 

Freezing ............................................................ 9 

Sudden pressure release ............................................ 9 

Solids in gaslines .................................................. 10 

Improved methods for monitoring gas production ........................... 10 

Conclusion ............................................................... 12 

Appendix A.--Proper pump-cycling procedures .............................. 13 

Appendix B..-Methods to prevent and control well unloading ............... 14 

ILLUSTRATIONS 

1 . Single-horizon (open hole) completion ................................ 3 

2 . Multiple-horizon completion .......................................... 3 

3 . Downhole water-production equipment .................................. 6 

4 . Surface water-monitoring equipment ................................... 7 

5 . Gas-production and monitoring equipment .............................. 8 
IMPROVED METHODS FOR MONITORING PRODUCTION 

FROM VERTICAL DEGASlFlCATlON WELLS' 

by 

S. W. Larnbert2 and M. A. Trevits2 

ABSTRACT 

In this Bureau of Mines investigation, production was monitored for 1 

year at over 30 coalbed gas-drainage boreholes located in Alabama, Pennsylvania, and West Virginia. Results indicate that the quality of data gathered 

from such wells can be improved greatly if potential problems are anticipated 

and prevented in the early stages of well production. 

Major water-monitoring problems include solids buildup, freezing, the 

presence of gas in surface waterlines, and improper pumping interval settings. 

Such problems may be avoided by incorporating in the original well design 

waterline filters, sand screens, separator tanks, and systems to automatically 

control pumping intervals. 

Problems related to measurement of coalbed gas flow include large quantities of water vapor contained in the gas, especially during winter months; 

freezing and subsequent obstruction of flow; sudden, uncontrolled release of 

gas pressure; and solids buildup in metering equipment. The installation of 

conunercially available items, such as filters, separators, and insulation, and 

the thoughtful application of a basic knowledge of coalbed gas reservoir characteristics will prevent most production-monitoring problems. 

INTRODUCTION 

In July 1974, a project was initiated to establish optimum well density 

for coalbed gas-drainage boreholes. Project design called for degasification 

of large tracts of land with possible eventual expansion to an entire coal 

basin. An early phase of project development was to design and implement an 

accurate means of measuring production from drainage boreholes. 

lThe work described in this report was performed by a component of the Bureau 

of Mines that was transferred to the Department of Energy on October 1, 

1977. 

2~eologist. 

Both authors are now with Pittsburgh Mining Operations, Department of Energy, 

Pittsburgh, Pa. (formerly with Pittsburgh Mining and Safety Research Center, 

Bureau of Mines, Pittsburgh, Pa. ) . 
Calculations of the effectiveness of any degasification program depend 

upon the quality of data collected as mining approaches and intercepts a borehole. Correlation of borehole production to reductions in face emissions and 

the derivation of coalbed reservoir parameters can be provided if sound information is available for analysis. 

ACKNOWLEDGMENTS 

The authors thank Leon DeBardelaben, drilling superintendent, and 

L. Graves, president, both of Graves Well Drilling Co., Inc., for their technical assistance in the field and helpful comments regarding pump design. 

GENERAL WELL COMPm TION 

Coalbed gas wells may be drilled or cored through one or several gasproducing coalbed horizons. An additional length of borehole is drilled below 

the lowest coalbed to allow water to drain from producing zones and provide a 

collecting pool from which water is pumped to the surface. 

Boreholes that produce gas from a single horizon are typically cased and 

cemented from immediately above the coalbed to the surface, blocking excessive 

drainage from upper water-bearing formations (fig. 1). Casing may also be 

set through several coalbeds along the full depth of the borehole. Gas is 

produced through openings which are either cut or pierced into the casing at 

each coalbed horizon. This manner of completion allows simultaneous production of gas and water from any number of selected horizons (fig. 2). 

METHODS OF REMOVING AND MEASURING WATER 

Water produced from exposed formations collects in the sump and is 

removed by means of a sucker-rod pump. Water is pumped up through 4- to 8-inchdiameter cased holes via production tubing, which is normally 1-112 to 2-318 

inches in diameter. The water is then piped through a positive-displacement 

meter and measured. The mechanical configuration used to drain water from 

coal gas wells was adapted from oilfield applications and has proved to be 

effective when water production is less than 100 bpd. 

A timing mechanism installed within the electric power circuit to the 

pump motor automatically controls pumping intervals. In this manner, a pump 

may be preset to operate only during designated intervals of each 24-hour 

period . 

PROBLEMS OF MONITORING WATER PRODUCTION 

Solids in waterlines have caused significant meter inaccuracies and pump 

malfunctions. Subfreezing temperatures have resulted in loss of water production data and permanent damage to wellhead equipment, pipes, and meters., 

Improper pumping intervals have allowed water to rise in boreholes to levels 

above the coalbed, thereby reducing gas production; or have allowed water to 

fall to the pump horizon, resulting in excessive wear of equipment. Such 

water-related problems can result in higher maintenance costs in terms of 
FIGURE 1. - Single-horizon (open hole) completion. FIGURE 2. - Multiple-hori
meter repair, rig time, and number of man-hours prescribed to insure proper 

well operation. 

Solids in Waterlines 

Water produced from coal gas wells, especially during early stages of 

production, normally contains small amounts of coal or other rock fines. 

Scale resulting from oxidation of casing and tubing is another comon ingredient of the water produced. If formation waters contain large percentages of 

salts, precipitates may enter surface flow lines, thus adding to the total 

solids content of the water. 

Except for very large particles, most solids pass through the waterproduction-and-monitoring system without difficulty. The small percentage of 

solids remaining in the system usually accumulates in the housing chamber of 

the water meter, impairing and eventually stopping the measuring mechanism. 

At some wells, water meters have performed several months without clogging; at 

many wells, however, meters have repeatedly clogged within 1 week. 

Rock material sometimes becomes lodged in valve openings in the downhole 

pump mechanism. Usually, this material is coal or shale that has sloughed off 

formations exposed in the wellbore. Pump stoppage due to lodging of rock 

material is most likely to occur during the first few days of production and 

especially after the well has been stimulated. 

Freezing 

In low temperatures, wellbore water sometimes freezes inside surface 

lines, restricting flow and causing leakage. Extended subfreezing conditions 

result in permanent damage to wellhead equipment, pipes, and meters. 

Gas-producing coals are normally several hundred feet deep, and the water 

drained is usually quite warm compared with winter surface temperatures. If 

pumping is controlled by a timing mechanism, there are periods when no water 

moves through surface lines. Water remaining in the lines during these 

periods cools rapidly and may freeze. 

Improper Pumping Interval 

To achieve maximum gas production from coalbed gas wells, borehole water 

levels must be kept below the lowest producing coalbed. This is accomplished 

by either operating pumps continuously, or time-cycling pumps to operate for 

certain intervals each day. 

Continuous pump operation wer extended periods (months) may result in 

excessive wear of mwing parts within the motor and the pump jack. Downhole 

pump components may also be worn quickly, especially when borehole water has 

been lowered to the pump horizon. Large volumes of gas are drawn into the 

pump causing dry to semidry conditions, which increase frictional wear. 
Several wells were equipped with a timing mechanism to control pumping 

intervals. Ideally, the mechanism is set to pump continuously when flow to 

the wellbore is high, and then adjusted as prescribed by changes in flow. At 

all sites, it was found that pumping intervals were improperly set. In some 

cases, the interval was too long, causing excessive pump wear and significant 

volumes of gas in the waterlines. Where the interval was too short, the fluid 

level was constantly above the coalbed, thus limiting gas and water production. 

Gas in Waterlines 

Gas passing through positive-displacement water meters is measured as 

water and may account for significant errors in production records. Such 

errors were found to be common, occurring to varying degrees at all wells 

examined. In some cases, gas accounted for up to 75 percent of the metered 

water volume. Gas may enter waterflow lines in the dissolved state (as minute 

bubbles of gas coming out of solution) or as free gas drawn directly into 

lines by the downhole pump. 

The solubility of coalbed gas increases directly as pressure increases, 

and diminishes as temperature increases. As much as 4 cubic feet of gas can 

be dissolved in 1 barrel of water at a depth of 1,000 feet, based on a hydrostatic pressure of 433 psig and a formation temperature of 100' F.~ AS pressure gradient is reduced around the wellbore, some of the dissolved gas comes 

out of solution and is produced through gas flow lines; however, a percentage 

of the dissolved gas remains in the water as it is pumped. As a result, gas 

comes out of solution while being brought to the surface and is measured 

through the water meter. Field tests to determine the degree of meter error 

resulting from such dissolved gases were conducted at several wells. At the 

start of the tests, borehole water levels were known to be at a static level 

well above the downhole pump horizon, which prevents large quantities of 

undissolved gas from entering waterlines. The meters used were checked for 

accuracy prior to and subsequent to the field tests. Results indicate that 

dissolved gases may account for 10- to 23-percent errors in measurements of 

water production. 

Improper cycle settings or continuous pump operation may lower water 

level in a borehole to the downhole pump horizon. If this occurs, gas is 

drawn directly into waterlines and pumped to the surface, causing large errors 

in metered water measurements. Tests conducted at wells where fluid levels 

were known to be at or near the base of the downhole pump show meter readings 

to be from 20 to 75 percent greater than the actual volume of water removed 

during testing . 

IMPROVED METHODS FOR MONITORING WATER PRODUCTION 

The gas contained in waterlines can be removed before the water is 

metered by incorporating a 30- to 50-gallon-capacity, vented separation tank 

in the surface waterflow system. Such tanks have been field tested at four 

"Uren, L. C. Water in Oil and Gas Reservoirs. Petrol. Production Eng., 3d 

ed. , 1953, pp. 30-32 .. 
producing wells where gas in waterlines had severely decreased meter accuracy. 

After the tanks were installed, meter accuracies increased to over 98 percent 

in all cases. The suggested position and installation design suitable for use 

at coalbed gas wells are shown in figure 3. 

Most large pieces of solid debris carried through waterlines settle in 

the separation tank. The remaining solids, suspended in the flow system, can 

be taken out of the water with a dirt-and-rust water filter installed downstream from the separation tank (fig. 3). The type of filter used at test 

well sites was a small plastic unit with a 314-inch-diameter connection and a 

replaceable filter cartridge. 

Downhole pump stoppage owing to lodging of large pieces of coal or other 

rock material can be averted by installation of a screen (12 openings per inch 

to 4 openings per inch) at the lower end of the water-production tubing 

(fig. 4). Stainless steel screens identical to those used in the water-well 

industry have been used successfully at three of the four wells tested. The 

failure at the fourth test site was due to the extremely small size of openings in the screen used. 

Cycled pumping, if properly controlled, is effective in controlling borehole water levels without causing unnecessary wear of equipment. Pump cycles 

must, therefore, be checked frequently and reset with every significant change 

in water production if optimum benefits are to be realized. (See appendix A.) 

FIGURE 3. - Downhole water-production equipment. 
Top electrode, 1 

A system that automatically controls pumping 

intervals to maintain water 

level below the coalbed is 

being tested at several well 

sites. Two electrode wires 

are fastened to waterproduction tubing as the 

tubing is lowered in the 

hole. One electrode is 

positioned near the bottom 

of the tubing and the other 

is placed just below the 

base of the coalbed. When 

the borehole water level 

rises to the top electrode, 

a circuit is completed that 

activates the pump jack 

motor (fig. 4). Water continues to be pumped from the 

well until the fluid level 

drops below the lower electrode. This system is 

expected to eliminate the 

frequent need to monitor 

fill-up rates (appendix A) 

and the possibility of drawing large volumes of gas 

through waterlines because 

FIGURE 4. - Surface water-monitoring equipment, the dmhole pump is always 

submerged in fluid. 

An alternative method to cycled pumpingisthe use of a variable-speed 

control on the pump. After the borehole water has been lowered to the pump 

horizon or near the intake, pump speed is reduced so the fluid level is held 

constant. Periodic checks for changes in the well's productivity might indicate a need to change the pumping interval. After shut-in periods or maintenance, the pump is adjusted to full capacity to dewater the wellbore rapidly 

Conditions favorable for unloading may be created; therefore, adequate precautions should be taken (appendix B). 

To prevent freezing, surface waterlines are wrapped with heat tape and 

then covered with fiberglass insulation. In areas where severe and prolonged 

low temperatures are comon, waterlines are buried below the frostline. In 

addition, meters, water filter, and separator tank should be contained in 

small, insulated meter houses. Heat lamps installed in meter houses have 

proved to be a simple, effective, and inexpensive preventative against freezing. (All houses should be ventilated to some degree, especially those in 

which heat lamps are employed.) 
METHODS OF REMOVING AND MEASURING GAS 

Gas from coalbeds is produced through the annular space between waterproduction tubing and borehole casing. Wells produce under no-back-pressure 

conditions to optimize coalbed gas desorption and formation-water drainage. 

Once the gas reaches the surface, it is piped through a positive-displacement 

meter where it is measured (fig. 5). Three types of meters have been used to 

measure coalbed gas production, depending on the volumes of gas produced. 

Diaphragm meters are normally used on nonstimulated wells that produce less 

than 10,000 cfd. The most common kind of meter used to monitor gas flow from 

stimulated wells is the rotary meter with a measuring capacity of up to 

84,000 cfd. Four-inch turbine meters have been used to monitor flows of wer 

84,000 cfd. 

FIGURE 5; - Gas-production and monitoring equipment; 
PROBLEMS OF MONITORING GAS PRODUCTION 

Gas produced from coalbeds contains water vapor that condenses and collects along various points in the gasline, including the meter. Field studies 

indicate that water buildup decreases meter accuracy and, in many cases, permanently damages working components. The effects of even small quantities of 

water in gaslines are most pronounced during periods of subfreezing weather 

conditions. Sudden pressure release after wells have been shut in results in 

temporary, large-volume gas flows, which are usually greater than can be accurately measured by the gas meter. Rock fines normally accumulate within the 

gas meter over a period of time, but solids buildup may accelerate if excessively high gas volumes are allowed to flow through lines. 

Water in Gaslines 

As warm coalbed gas is subjected to cooler surface temperatures, some of 

its ability to carry moisture is lost; therefore, condensation occurs. The 

water condensate accumulates at low points along the pipeline and in metering 

devices. The problem occurs frequently during winter months, when differ - 

ences between gas temperature and surface temperature are the greatest. 

Reduction of gas flow velocity also causes water to separate from gas; 

this occurs in areas where pipe diameter increases, thus providing favorable 

sites for liquid accumulation. 

Finally, water is stripped from the gas stream at angled sections along 

surface flow lines and ,meter locations where temporary turbulent flow occurs; 

this results from the collision or impingement of gas against pipe walls or 

meter chamber, causing some moisture to be extracted from the flow. 

Freezinq 

The problem of water in gaslines is greater during periods of low temperature because conditions for condensation are intensified. The problem becomes 

acute when temperatures drop to below freezing. Even small amounts of ice in 

gas flow lines cause back pressure, resulting in apparent low coalbed gas production. Formation of ice in gas meters has damaged many of the instruments 

since the Bureau first began its coalbed gas-drainage program several years 

ago. 

Sudden Pressure Release 

Sudden, uncontrolled release of gas pressure has been a major cause of 

meter inaccuracies and has resulted in severe meter damage on many occasions. 

Gas flow from the well is shut off routinely for pipe or meter maintenance, or to test for pressure buildup. During the shut-in period, gas continues to flow from the coalbed, building pressure in the wellbore. When the 

pressure is released quickly, a sudden surge of gas, or pressure wave, strikes 

the meter. Diaphragm meters are especially vulnerable to this surge and are 
almost always damaged. Rotary and turbine meters, although not damaged as 

easily, have been rendered inoperable by sudden surges of pressure. 

Although damage to the meter may not occur, significant errors have 

resulted from recording measured gas volumes during a period of gas-pressure 

release. When gas is moving under pressure, more volume (at standard temperature and pressure) passes through the meter than is actually indicated on the 

meter index. If the necessary correction multipliers for gas flow under pressure are not applied, incorrect volume measurements may result. 

Sudden pressure release has occurred at several wells because water was 

allowed to build up in the wellbore. Normal pumping operations may be temporarily interrupted for a number of reasons, such as electric power failure, 

mechanical malfunction, or general maintenance. As the fluid level rises, gas 

production to the surface decreases in proportion to the increasing hydraulic 

pressure exerted on the coalbed. Field studies indicate, however, that gas 

continues to accumulate around the wellbore periphery, building pressures 

similar to those exerted by the increasing hydraulic head. Once pumping is 

resumed and the borehole water level is lowered, disequilibrium is created in 

which gas pressure in the coalbed exceeds hydraulic head. As a result, violent eruptions occur at the surface as large volumes of expanding gas travel 

up the wellbore to reestablish pressure equilibrium. Sudden gas-pressure 

release of this nature is referred to as ''unloading." 

Solids in Gaslines 

Particles of rock or other solid material accumulate in most gas meters 

over extended periods of time under normal flowing conditions. If left 

unchecked, solids cause malfunctions in all types of meters used. Field 

experience indicates that rotary meters are the most susceptible to malfunction caused by solids because of the close clearance between components of the 

inner rotating cartridge. Diaphragm meters usually do not stop functioning 

with small amounts of solids buildup, but meter accuracy diminishes as a portion of the measuring reservoir is filled with solids. Turbine meters will 

normally allow very small (less than 1 millimeter in diameter) material to 

pass through inner mechanisms. 

Larger solids are normally carried through gaslines when well pressure is 

suddenly released, especially when unloading occurs. Such solids almost 

invariably clog and usually damage inner meter components. 

IMPROVED METHODS FOR MONITORING GAS PRODUCTION 

Commercially available filters have been designed to remove fine solid 

particles with very little pressure drop (0.5 psig or less), which makes them 

suitable for use on coalbed gas wells. Filters have been tested only on gaslines equipped with rotary meters, but they are adaptable to other meter 

types. Fiberglass is normally the filtering element used. At one test well 

equipped with such a filter, the gas meter operated for over 1 year without 

malfunctioning or losing accuracy. Suggested in-line placement of gas filters 

is indicated in figure 5. 
The moisture content of coalbed gas has to be sufficiently low to assure 

accurate measurement of gas flow. In addition, coalbed gas sold comnercially 

must meet requirements specifically noted in purchase agreements which norually limit the water content to approximately 7 pounds of water per million 

cubic feet of gas measured at standard temperature and pressure. During cold 

weather periods, test wells (ranging from 1,053 to 1,076 feet deep) have been 

found to contain from 31 to 103 pounds of water per million cubic feet of gas 

produced.4 Although gasline condensate buildup has been a chronic problem at 

many Bureau vertical test wells, experimentat ion with water -gas separation 

devices has been limited because most of the gas produced is not sold. 

The basic means used to remove moisture from coalbed gaslines are cooling, 

absorption, and impingement. Devices used to remove liquid impurities are 

drips and separators. 

The basic function of a drip is to remove liquid from the gas stream or 

liquid that has accumulated within the pipeline. A drip catches liquid in a 

gas stream by reducing the velocity of the gas stream, which causes the liquid 

to drop out. Liquid that has accumulated at low points within the pipeline is 

removed by use of a drip equipped with a drain which operates automatically or 

manually. 

The primary function of a separator is to remove entrained fluids from 

the gas stream. Baffles, deflectors, tubes, rare elements, and gravity separation chambers are some of the mechanisms used within a separator device to 

remove moisture. There are several comnercially designed separators that meet 

requirements for a single well or for several wells in the same pipeline 

system. 

Meter inaccuracy and possible meter damage caused by sudden pressure 

release can be avoided by allowing gas pressure to bleed off gradually while 

maintaining flow pressures within the given meter range. To do this, a pressure gage is installed in the gas flow line near the meter. Flow pressures 

are periodically recorded and are then calculated into a standard equation 

solving for actual flow. 

Sudden pressure release that results in unloading can be avoided if a few 

precautionary steps are taken, such as gasline shut-in, resumption of pumping, 

and subsequent slow bleedoff. Detailed description of actions to be taken if 

unloading is anticipated is included in appendix B. These methods have been 

field tested on several occasions and have proved to be very effective. 

Ice formation in gaslines near the wellhead is prevented by properly 

insulating and heating meters and other points favorable to water accumulation 

(fig. 5). The number of routine field inspections of wells should be 

4Based on volumes of condensate accumulated in a flare stack similar to that 

shown in figure 5. 

'~umbau~h, J. R. Gas Conditioning Before Measurement. Pres. at 36th Appalachian Gas Measurement Seminar, Pittsburgh, Pa., Aug. 10-12, 1976; available 

for consultation at Department of Energy Mining Operations, Pittsburgh, Pa. 
increased during especially cold periods to assure minimum condensate buildup. 

At the test wells examined, gaslines that had been wrapped with electric heat 

tape and covered with fiberglass insulation were rarely found to contain sufficient amounts of ice to cause significant back pressure. In addition, well 

sites equipped with insulated meter houses containing heat lamps yielded accurate, uninterrupted production information, even during prolonged subfreezing 

weather conditions. 

CONCLUSION 

Results of this study indicate that the quality of data gathered from 

degasification wells can be significantly improved if potential problems are 

anticipated and prevented during the early stages of well production. Problems related to the measurements of both gas and water can generally be 

avoided by equipping wells with commercially available items and by applying 

a basic knowledge of the coalbed reservoir throughout the productive life of 

the well. 
APPENDIX A.--PROPER PUMP-CYCLING PROCEDURES 

1. Pump the well continuously until a marked decrease in water production (compared with specified pump capacity) is observed. At new wells, it 

may take several weeks for this decrease to occur. At wells that have been 

pumped regularly, the decrease in water production rate may be observed in a 

few hours. At wells where pumping has been continuous, no decrease will be 

observed. 

2. Measure and record the continuous, low-vclume flow, using a device 

other than the water meter. A 5- or 10-gallon container and a stopwatch are 

sufficient to record such flow rates. 

3. Turn off the pump jack and allow fluid to rise above the position of 

the downhole pumping mechanism. This usually takes less than a few hours. 

(The rate of waterflow into the well is known from item 2. The approximate 

volume of water and the time necessary to raise the level of water above the 

downhole pump is calculated from the known dimensions of the borehole and the 

production tubing within.) Unnecessarily long periods (days) of nonpumping 

should be avoided (appendix B). 

4. Resume pumping and monitor flow as specified in item 2. Waterflow 

will increase rapidly to the current maximum pump capacity and remain at this 

high flow rate until the water level in the borehole is lowered to the downhole pump horizon. Once this occurs, water flow rate falls quickly (within 

5 to 10 minutes) and is usually accompanied by an increase in gas flow through 

the waterlines. 

5. Allow the pump to operate continuously until water flow rate is 

similar to that measured in item 2. 

6. Given the rate of waterflow into the borehole (measured in items 2 

and 5) and the dimensions of the wellbore and production tubing, the time 

(pump "off" cycle) required to fill the sump below the coalbed is calculated. 

Given the current real pump capacity (measured in item 4), the time (pump "on" 

cycle) required to remove water from the sump can also be calculated. Pump 

cycles are set accordingly and rechecked periodically to assure proper coalbed 

water drainage. 
APPENDIX B.--METHODS TO PREVENT AND CONTROL WELL UNLOADING 

1. In most cases, gaslines should be closed as soon as possible after 

pumping has been interrupted. The objective is to build gas pressure in upper 

portions of the borehole above the water column. However, if well maintenance 

requires gaslines to remain open, the borehole should be filled with water . before work begins. 

2. Once pumping is resumed, water production should be monitored closely 

at the wellhead (not through the water meter) for one of the following indications that the borehole water level has been lowered to or near the downhole 

pump horizon: 

a. Sharp reduction of water production rate (compared with pump 

capacity). 

b. Sharp increase in the quantity of gas coming through water1ines.l 

3. Gaslines may be opened as soon as borehole water level is determined 

to be at or near downhole pump horizon. Gas valves should be opened very 

slowly to allow gradual bleedoff of gas pressure. 

4. If well has shown a tendency to unload, allow pump to operate continuously until initial high formation pressures are reduced. Several months 

of continuous pumping may be required. 

IBecause the borehole is under pressure, large volumes of water (several times 

pump capacity) sometimes accompany gas through waterlines. If this should 

occur, pumping should be discontinued until pressure in the wellbore is 

reduced. 

sU.S. GOVERNMENT PRINTING OFF ICE: 1978-703-103167