Page 3 - Acoustic Fluid Level Measurements

iv ACOUSTIC FLUID LEVEL MEASUREMENTS IN OIL AND GAS WELLS HANDBOOK

Petroleum Extension-The University of Texas at Austin
Example 9, Stratified Annular Gas Column 2-30
Variation of Gas Composition with Depth 2-34
Summary 2-35
References 2-36
3. Fundamentals of Acoustic Fluid Level Surveys 3-1
Sound Pulse Generation and Wave Propagation 3-1
General Solution of the Wave Equation 3-2
Characteristic Diagram in the z,t Plane 3-5
Reflection and Transmission of a Plane Wave 3-7
Reflection at the Discontinuity of Fluid Properties 3-7
Reflection and Transmission at a Geometric Discontinuity 3-11
Sound Pressure Wave Propagation in Pipes and Annuli 3-13
Acoustic Velocity in Gases 3-15
Effect of Gas Composition, Pressure, and Temperature on Acoustic Velocity 3-16
Acoustic Signal Amplitude Reduction 3-20
Summary 3-23
References 3-23
4. Acoustic Fluid Level Equipment and Procedures 4-1
Acoustic Pulse Generation and Signal Acquisition 4-1
Pulse Generation 4-5
Manual Pulse Generation 4-5
Explosion versus Implosion Pulses 4-7
Automatic Pulse Generation 4-8
Other Pulse Generation Methods 4-9
Acoustic Record Acquisition and Recording 4-10
Microphones 4-10
Signal Recording and Processing 4-11
Safety Considerations 4-11
Hazardous Locations in the Oilfields 4-12
API Classification of Drilling and Production Facilities 4-12
Recommended Operating Procedures 4-13
Installation of Sound Source 4-14
Well Preparation and Information 4-14
Acquisition and Recording 4-15
Random Acoustic Signals 4-16
Pumping-Related Noise 4-17
Gas Flow Noise 4-18
Calibration and Maintenance 4-18
Summary 4-19
References 4-19
5. Methods of Determining Distance to the Liquid Level 5-1
Converting Acoustic Pulse Travel Time to Distance 5-1
Collar Count Method 5-2
Stepwise Collar Echo Count 5-4
Automatic Digital Filtering 5-6
Distance to a Known Wellbore Anomaly (Downhole Marker Analysis) 5-8
Calculating Acoustic Velocity from Gas Gravity or Composition 5-10
Estimating Acoustic Velocity from Similar Wells or Past Acoustic Surveys 5-13
Recommendations for Background Noise 5-15
Summary 5-15
References 5-16

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