Echometer Gun - Microphone Assemblies

For use with Acoustic Liquid Level Instruments

 

Compact Gas Gun	Remote Fire Gas Gun
5000 PSI Gas Gun	15,000 PSI Gas Gun

 

A Gun-Microphone assembly consists of a gun and microphone together. A gun generates a pressure pulse. A microphone converts acoustic pressure pulses into an electrical signal. The gun and microphone are normally supplied together as a unit.

The gun generates a single pressure pulse which travel down the casing annulus gas and is reflected by collars and the liquid level. The reflected pressure waves deflect the microphone and generate an electrical signal. The electrical signal is fed to the computerized Well Analyzer which automatically processes the signal or to an amplifier-recorder which amplifies, filters and records the signals on a strip chart.

Two types of guns are available. One type utilizes gas and is a gas gun. The other type utilizes blanks containing black powder. The gas guns offer many advantages over blank cartridge guns. Two important factors must be considered when selecting the type of gas gun. First, the gun should generate a pressure pulse that results in the collars being counted as far down the well as possible. Second, the gun must generate a pressure pulse of sufficient strength to cause the reflected pressure wave from the liquid level to be readily distinguishable. The reflected liquid level pressure wave is larger when the volume or pressure of gas discharged into the casing annulus is increased. On deep, slim hole, low pressure wells, the liquid level response may be weak unless a large initial pressure pulse is used.

The Compact and 5000 PSI Gas Guns are manually operated in either the explosion mode or the implosion mode. On low-pressure wells (less that 200 PSI), the gas gun is used in the explosion mode. That is, the gas gun volume chamber is pressured above the casing pressure Opening the gas valve results in a positive compression pressure wave being generated which travel down the casing annulus gas. On wells having over 200 PSI casing pressure, the gas gun can be operated in the implosion mode. That is, gas is rapidly released from the well into the gas gun volume chamber to generate a negative rarefaction pressure pulse. A compressed gas source is not needed in the implosion mode. Operating the Compact Gas Gun in the implosion mode allows debris from the well and the necessary replacement of o-rings occasionally. Operating the Compact Gas Gun in the implosion mode is not recommended if pressurized gas is available at a pressure greater than the casing annulus pressure. The 5000 PSI Gas Gun is normally used only in the implosion mode. The 5000 PSI Gas Gun has an excellent noise canceling microphone and generates a "good" pressure pulse when the ½" ball valve is rapidly opened and the well pressure exceeds 200 PSI. When the 5000 PSI Gas Gun becomes dirty due to debris, the volume chamber and microphone assembly can be flushed with a solvent to remove the debris. The 5000 PSI Gas Gun requires very little maintenance. It is excellent for gas lift, flowing and high-pressure shut-in wells.

A Remote Fire Gas Gun utilizes a high performance microphone having an excellent signal-to-noise ratio along with a 12 cu. in. volume chamber. A solenoid valve releases gas from the gas gun volume chamber into the well. The solenoid is operated automatically from the Well Analyzer system, the Model M, or by a 12-volt cigarette-lighter outlet. The Remote Fire Gas Gun cannot be operated in the implosion mode. The Remote Fire Gas Gun is required for automatic acquisition of pressure transient data. It is normally supplied with a 1500 PSI pressure gauge and a 1500 PSI pressure transducer. The Remote Fire Gas Gun is limited to 1500 PSI working pressure. For single shot analysis, the 5000 PSI implosion gun is preferred when the well pressure exceeds 1500 PSI.

Carbon dioxide or nitrogen gas is normally used with gas guns when operating in the explosion mode. Carbon dioxide is obtained from welding supply firms, fire extinguisher firms and the soft drink preparation firms. The Compact Gas Gun and Remote Fire Gas Gun can be recharge using 2.5 pound or 5 pound CO2 gas cylinders container of CO2. A push type, quick connect flexible filler connector hose attached to the CO2 container will bleed gas into the gas gun volume chamber, when the connector is mated into the gas gun. Approximately 100 charges per lb. of CO2 can be obtained from a CO2 gas container. If more charges are desired a 5 pound bottle can be utilized. The portable 2.5 pound and 5 pound cylinders are generally filled from a stationary 50 pound siphon-type bottle located at a field office. Approximately 5000 tests can be obtained from the 50 pound bottle. A large amount of CO2 gas can be contained in relatively small cylinders. Carbon dioxide gas is commonly supplied in approved CO2 cylinders with the pressure in the cylinder being the vapor pressure of the carbon dioxide gas at the particular temperature of the carbon dioxide cylinder. The critical temperature is 88° F and the pressure in the bottle (if gas and liquid exist in the bottle) at 88° F will be 1070 PSIA. If the bottle contains liquid, the pressure is 650 PSI at 50° F, 300 PSI at 0° F and 120 PSI at -50° F. As long as the temperature of the CO2 gas is high enough that the vapor pressure exceeds the well pressure, carbon dioxide gas is most convenient gas to use for acoustic testing. If the well pressure exceeds the vapor pressure of carbon dioxide, then nitrogen gas is the most common gas to use for acoustic testing. Generally, nitrogen gas is supplied at 2200 PSI and the pressure is in excess of the needed pressure to charge the gas gun. A pressure regulator is commonly used to reduce the nitrogen pressure to a pressure satisfactory for charging the gas gun volume chamber. For example, if the maximum pressure on the wells to be tested is 500 PSI, the pressure regulator might be set for 750 PSI. When performing pressure transient testing, the well pressures are increasing. At night, the temperature may become cold and the vapor pressure of carbon dioxide gas may be below well pressure. This requires the use of nitrogen gas or some other gas, which has a pressure in excess of well pressure. An operator may prefer to use carbon dioxide for conventional well testing and use nitrogen bottles with a regulator when performing pressure transient testing.

Gas guns have several advantages over blank cartridge guns and should be specified on all overseas orders. 1) A gas gun is much safer. Burning particles of black powder which could result in injury to people or present a fire hazard are not discharged. 2) The gas guns are less expensive to operate. Compressed gas is much cheaper than blanks. 3) The blanks can be difficult to ship, especially overseas. 4) The gas gun microphones are superior and more reliable. Please request information on blank cartridge guns if your conditions are such that blank cartridge guns are the only choice for you particular application.

Contact Echometer Company for additional details about computer programs, acoustic velocity charts, articles on field data and calculation of bottomhole pressures.

15,000 PSI GAS GUN (1000 ATM)

A High Pressure Gas Gun will operate up to 15,000 PSI. The test pressure is 30,000 PSI. The 15,000 PSI Gas Gun operates in the implosion mode only. The volume chamber in the gas gun is bled to a pressure less than the pressure existing on the well. Then, a poppet valve is rapidly opened to release gas from the well into the gas gun volume chamber to generate the pressure pulse. The microphone is not as sensitive or noise canceling as the microphone on the Compact Gas Gun, Remote Fire Gas Gun or the 5000 PSI Gas Gun. Best performance will be obtained when the 15,000 PSI Gas Gun is used at pressures exceeding 1500 PSI, but not exceeding 15,000 PSI. The gas gun is useful in determining liquid levels, bottomhole pressures, locating the liquid level of corrosion inhibitors, and locating other anomalies. Excellent results have been obtained at pressures above 1500 PSI (100ATM) through 1/8" orifice needle valves, which are standard on most high pressure wells. Minimum expense and trouble are involved in the use of this High Pressure Gas Gun..

GAS GUN SPECIFICATIONS AND GENERAL INFORMATION
	COMPACT GAS GUN	REMOTE FIRE GAS GUN	5000 PSI GAS GUN	15000 PSI GAS GUN
VOLUME CHAMBER SIZE, IN	10	12.5	7	1
WORKING PRESSURE   PSI (ATM)	1500 (10)	1500 (100)	500 (333)	15,000 (1000)
BEST OPERATING  PRESSURE PSI (ATM) MIN/MAX	0-1500 (0-100)	1-1500 (0-100)	0-200  (0-13) EXP 200-5000   (13-333) IMP	1500-15,000 (100-1000)
MODE OF OPERATION	EXPLOSION / IMPLOSION	EXPLOSION ONLY	EXPLOSION / IMPLOSION	IMPLOSION
TYPES OF OPERATION	MANUAL	AUTOMATIC/ SOLENOID	MANUAL	MANUAL
DIMENSIONS	2-3/8” SQUARE X 12” LONG	2-3/8” SQUARE X 12” LONG	2” SQUARE X 16” LONG	2-3/8” SQUARE X 8” LONG
WEIGHT	8 LBS.	12 LBS.	10 LBS	10 LBS
MICROPHONE	DUAL DISC NOISE CANCELING	DUAL DISC NOISE CANCELING	DUAL DISC NOISE CANCELING	SINGLE DISC
All gas guns are constructed from 303 and 316 stainless steel and are suitable for H2S and corrosive service.

 

GENERAL INFORMATION

A 2 1/2 lb CO2 cylinder is supplied in the USA and a 5 lb. cylinder is supplied overseas, unless the customer requests the other option. A hose and a filler connector are supplied. The CO2 gas cylinders are constructed of aluminum and have a test pressure of 3000 PSI and a service pressure of 1800 PSI. Dimensions for 5 lb. CO2 gas cylinders are 18" long by 5.25" O.D. Weight is 7.8 lbs. Dimensions for 2.5 lb. CO2 gas cylinders are 14" long by 4.37" O.D. Weight is 4.6 lbs. The capacity for the CO2 cylinders is sufficient for 100 tests per lb. of CO2. The gas valve has 0.965-14 NGO R.H. external thread.

Nitrogen bottles are constructed of aluminum and have a test pressure of 3694 PSI and a service pressure of 2216 PSI. Dimensions are 42" long by 8" O.D. Weight is 43 lbs. Capacity is 115 cu. ft. of N2 gas at 2216 PSI. The gas valve has 0.965-14 NGO R.H. internal thread.

PRESSURE REGULATORS

A pressure regulator is available for use with the nitrogen gas cylinder, which will reduce the pressure to a preset level that can be set by the operator ranging from 50 to 1500 PSI. This can be used during single sot or pressure transient data acquisition.

USA PATENTS 4,408,676 4,637,463 4,793,178 4,932,253 4,934,186 5,117,399 5,200,894 5,285,388 5,406,482 5,464,058 Approved and others pending CANADA 2,037,277 and others