Gas Well Deliquification Workshop Sheraton Hotel, Denver, Colorado February 17 20, 2013 Intrinsically Safe Acoustic Instrument Used in Troubleshooting Gas Lift Wells Lynn Rowlan, Echometer Company Carrie-Anne Taylor, Echometer Company
Offshore Platform Santa Barbara California Technician s Van & Wellhouse: Alaska s North Slope Stringent safety requirements, by major operators when fluid level measurements are performed offshore or in enclosed wellhead spaces such as in Alaska s North Slope, create procedural complications. Feb. 17 20, 2013 2013 Gas Well Deliquification Workshop Denver, Colorado 2
Intrinsically Safe Acoustic Instruments 1. Some operators require Safe instruments in certain locations, most offshore platforms and certain fields. 2. Some Countries and States require Safe instruments in all oil and gas related operations. 3. Gas Lift is common artificial lift method for high rate wells Feb. 17 20, 2013 2013 Gas Well Deliquification Workshop Denver, Colorado 3
Fluid Level on Gas Lifted Horizontal Well 128 BL/D 140 Mscf/D Liner Top Liquid Level at Measured Depth of 10061 Feet Above Packer (10081 ) and Bottom Valve (10041 ) Feb. 17 20, 2013 2013 Gas Well Deliquification Workshop Denver, Colorado 4
Echoes from Gas Lift Mandrels Do Not Lineup Press = 513 psig Temp = 70Deg F Press = 688 psig Temp = 180Deg F E Average Acoustic Velocity 1134 ft/sec from Echo off 4.5 Liner Top Liner Top Used for Distance to LL Feb. 17 20, 2013 2013 Gas Well Deliquification Workshop Denver, Colorado 5
Acoustic Velocity Increases from 1072 ft/sec @ Surface to 1238 ft/sec at the 10061 ft Liquid Level Surface Press = 688 psia Temp = 180Deg F Press = 513 psia Temp = 70Deg F Feb. 17 20, 2013 2013 Gas Well Deliquification Workshop Denver, Colorado 6
Anomaly Marker Analysis Method Purpose Accurately calculate the distance to the liquid level plus other downhole reflectors such as gas lift valves, tubing collars, subsurface safety valves and possible holes or other problems. Distances Determined using echoes from gas-lift valves at known distances from the wellhead. Accounts for Variations of acoustic velocity commonly observed in most wellbores due to variations of temperature, pressure and gas composition as a function of depth. Feb. 17 20, 2013 2013 Gas Well Deliquification Workshop Denver, Colorado 7
Anomalies are Markers in the Well at Known Distances Anomaly distances are entered as Well Marker Info Initially based on an estimated acoustic velocity, tick marks along the depth axis are located at distances that would correspond to the location of the anomaly echoes. Anomalies don t match echoes, relocates each tick mark to match exactly the beginning of the echo for a specific anomaly. Anomaly echoes are fixed to known depths by starting from the first anomaly, then from the first anomaly to the second anomaly and so on until the distance to the liquid level is accurately determined. Feb. 17 20, 2013 2013 Gas Well Deliquification Workshop Denver, Colorado 8
Anomaly Analysis Example Noisy Initial Acoustic Trace With Anomaly Echoes Collars Anomaly Echo Feb. 6-10, 2012 2012 Gas-Lift Workshop 4 9
See Echoes Better by Removing Noise From Acoustic Trace Scale up trace to see better. 10
Identify/Select Correct Liquid Level Echo Move the LL marker to the knee of the kick. 11
Liquid Level Depth is Approximate 12
Known Depth of Anomalies 13
Make Depth Accurate by Identifying Each Anomaly SSSV 14
Next Anomaly Automatically Selected At first glance, it appears the automatic pick of marker is a little to the left of the kick. 15
Fine Tune Location of Selected Anomaly But we also see a kick to the left of the marker. Some quick calculations tell us that this is not a repeat. Select Interval Left to get a clear picture of the reflection located just below the 6 second mark. 16
Examine the Acoustic Trace and Select Correct Echo This is a much more likely position for the placement of the next marker. 17
Continue Down Trace Selecting Anomaly Echoes If the correct marker is not selected, then move window to see the marker echo. 18
Continue Down Trace Selecting Anomaly Echoes 19
Continue Down Trace Selecting Anomaly Echoes Scale UP if needed to verify that this is the last marker before the liquid level. 20
Anomaly Echoes Below the Liquid Level are Negligible Gas Lift Mandrel 8 and the Packer are below the liquid level marker so these last two markers can be skipped. 21
Accurate Distance to Liquid Level Using Anomaly Depths 22
Discussion of Anomaly Analysis New Technology Does the Calculations on the Acoustic Trace for You Identifying Anomaly Echoes is Simplified Marker Depths are Automatically Determined Manual Adjustments Required For Accuracy Data is digital and not on a Strip of Paper, so Safe Backup of Information is Done Recall of Data and Re-analysis is a Straight Forward Process Feb. 17 20, 2013 2013 Gas Well Deliquification Workshop Denver, Colorado 23
Intrinsically Safe Equipment Intrinsically safe equipment and wiring shall not be capable of releasing sufficient electrical or thermal energy under normal or abnormal conditions to cause ignition of a specific atmospheric mixture in its most easily ignited concentration. Feb. 17 20, 2013 2013 Gas Well Deliquification Workshop Denver, Colorado 24
Classification of Hazardous Zones Rod Pumped Well: API-RP500 Division 1 Zone In the sump; Hydrocarbon gases heavier than air may accumulate. Division 2 Zone Surrounding the tree, stuffing box, and a portion of the flowline. Feb. 17 20, 2013 25
Feb. 17 20, 2013 2013 Gas Well Deliquification Workshop 26 Denver, Colorado Explosion Prevention Methods Explosion-Proof Enclosures Purging or Pressurization Encapsulation Oil Immersion or Powder Filling Intrinsic Safety
Feb. 17 20, 2013 2013 Gas Well Deliquification Workshop 27 Denver, Colorado Requirements for Intrinsic Safety Simple Apparatus Thermocouples, RTD s, switches, LED s Strain Gage type pressure transducer, dynamometer load cell transducers Intrinsically Safe Certified Apparatus Transmitters, current to pressure converters, solenoid valves, piezoelectric microphones Intrinsic Safety Barrier
Feb. 17 20, 2013 2013 Gas Well Deliquification Workshop 28 Denver, Colorado Intrinsically Safe Field Devices Gas Gun Acoustic Instruments Microphones used in the wellhead attachments include piezoelectric crystals. Special intrinsic safety barrier microphones are manufactured. Solenoid device on the remotely fire gas guns must be Encapsulated and power line must be Pressurized for intrinsic certification. So often the acoustic instrument will be manually operated and fired.
Intrinsically Safe 5000 psi Gas Gun Often used to Shoot Gas Lift Wells 5000 psi rated Gas Gun is modified, as shown by the engravings, with a special microphone for use in hazardous areas. Feb. 17 20, 2013 2013 Gas Well Deliquification Workshop 29 Denver, Colorado
Feb. 17 20, 2013 2013 Gas Well Deliquification Workshop 30 Denver, Colorado Intrinsically Safe Fluid Level Instruments Computerized Recorder or Strip Chart Recorder Modified with safety circuits to limit electrical energy output in the event of a component malfunction. Must be installed in a safe area when used with the certified gas guns that are located in a hazardous area.
Installation Drawing for Instrument with Intrinsic Safety Barrier Intrinsic Safety Barrier
Intrinsically Safe Fluid Level Instrument Located in Hazardous Area When installed correctly and used in conjunction with a certified field device is approved for use inside hazardous environments. 32
Conclusion Intrinsically Safe Field Instruments 1500psi Compact Gas Gun 5000psi Gas Gun, also design/construction materials meet MR-01-75 to allow use in corrosive CO2 and H2S environments Intrinsically Safe Fluid Level Instruments Model M Chart Recorder (Install and operate within Safe Zone) Model H Digital Recorder (Can be operated within Hazardous Zone) Intrinsically Safe Computerized Well Analyzer Model E (Install and operate within Safe Zone) Pressure Transducer, Strain Gage Dynamometer transducers considered Simple Apparatus Feb. 17 20, 2013 2013 Gas Well Deliquification Workshop Denver, Colorado 33
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