Acoustic Liquid- -Level Determination of Level Determination of - PowerPoint PPT Presentation

Gas Well De-Liquification Workshop Adams Mark Hotel, Denver, Colorado March 5 - 7, 2007 Acoustic Liquid- -Level Determination of Level Determination of Acoustic Liquid Gradients and BHP in Flowing Gas Wells Gradients and BHP in Flowing Gas Wells O. Lynn Rowlan O. Lynn Rowlan – – Echometer Company Echometer Company A. L. Podio – – University of Texas at Austin University of Texas at Austin A. L. Podio James N. McCoy – – Echometer Company Echometer Company James N. McCoy http://www.nitrolifttechnologies.com/

Introduction Introduction 1. 1. Many Studies done on Critical Rates and Gradients Many Studies done on Critical Rates and Gradients 2. 2. Flow Regime Maps, Critical Velocity Curves, and S- - Flow Regime Maps, Critical Velocity Curves, and S Curves all Relate to Gas & Liquid Flow Rates Curves all Relate to Gas & Liquid Flow Rates 3. 3. Acoustic Measurement of Mist Gradients Possible Acoustic Measurement of Mist Gradients Possible When Well Flowing Above Critical Rate. When Well Flowing Above Critical Rate. 4. 4. Gradients Below the Liquid Level is a Function of Gradients Below the Liquid Level is a Function of the Gas Flow Rate in Liquid Loaded Wells the Gas Flow Rate in Liquid Loaded Wells 5. 5. Field Developed Correlation Determines Gradient Field Developed Correlation Determines Gradient Below the Liquid Level in Liquid Loaded Wells Below the Liquid Level in Liquid Loaded Wells 2007 Gas Well De-Liquification Workshop 2 Mar. 5 - 7, 2007 Denver, Colorado

Critical Gas Velocity Occurs at Critical Gas Velocity Occurs at Instability Point on Tubing Capacity Curves Instability Point on Tubing Capacity Curves Inflow I n flo w Buoyant Gas Well Buoyant O u tflo w Tubing weight of Liquid weight of Liquid Parameters droplet in droplet droplet in droplet suspended suspended suspended suspended GLR gas in flowing Loaded gas Loaded in flowing gas gas Can Can Flow Flow Pressure Qg < Qc Qg < Qc Qg > Qc Qg > Qc VSL = 0 VSL = 0 Instability Instability Flowing Gas Rate R a te Drag from flowing gas tending to Drag from flowing gas tending to lift the droplet lift the droplet 2007 Gas Well De-Liquification Workshop 3 Mar. 5 - 7, 2007 Denver, Colorado

If Well Flow Rate Exceeds Minimum Critical If Well Flow Rate Exceeds Minimum Critical Velocity, then No Liquid Loading Predicted Velocity, then No Liquid Loading Predicted Loaded Gradient ~ 0.08 psi/ft Gas Velocity Gas Velocity Removes Liquid Removes Liquid Qg > Qc Qg > Qc Qg < Qc Qg < Qc Liquid Loading Liquid Loading Predicted Predicted Flowing Pressure (Psia) Flowing Pressure (Psia) 2007 Gas Well De-Liquification Workshop 4 Mar. 5 - 7, 2007 Denver, Colorado

Depth & Liquid Rate Depth & Liquid Rate MscfD MscfD Guo, B.: , B.: “ “A Systematic Approach to Predicting Liquid A Systematic Approach to Predicting Liquid Guo Loading in Gas Wells“ “, SPE94081 POS 04/17/05 , SPE94081 POS 04/17/05 Loading in Gas Wells Well Depth and Liquid Well Depth and Liquid Production Rate May Production Rate May V SG > 10 V SG > 10 Impact Critical Rate Impact Critical Rate 1. Coleman 20% Adjustment Coleman 20% Adjustment 1. to Turner Under Predicts to Turner Under Predicts Critical Rate Critical Rate 2. Bottomhole Bottomhole Conditions Conditions 2. Control Critical Rate Control Critical Rate V SL V SL = = 3. Liquid Flow Rate NOT Liquid Flow Rate NOT 3. 0 0 Considered in Critical Q? Considered in Critical Q? 2007 Gas Well De-Liquification Workshop 5 Mar. 5 - 7, 2007 Denver, Colorado

Range of Gradients in a Gas Well Range of Gradients in a Gas Well 2.375” ” Tubing, 0.7 Tubing, 0.7- -SG Gas, 300 Psia Wellhead Pres SG Gas, 300 Psia Wellhead Pres 2.375 Qg < Qc Qg < Qc Qg = 0 Qg = 0 Qg > Qc Qg > Qc 2007 Gas Well De-Liquification Workshop 6 0.08 psi/ft Mar. 5 - 7, 2007 Denver, Colorado

Coleman ”Liquid Removed from the Well when Qgas Exceeds Qcritical, Loading Occurs when Qg<Qc” SPE20801 " Understanding Gas Well Load up Behavior" S. B. Coleman n JPT, March 1991 JPT, March 1991 SPE20801 " Understanding Gas Well Load up Behavior" S. B. Colema Qg < Qc Qg < Qc Qg > Qc Qg > Qc Qg = 0 Qg = 0 Gas Gradient >0.02 psi/ft Loaded Gradient 0.08 to 0.04 psi/ft 2007 Gas Well De-Liquification Workshop 7 Mar. 5 - 7, 2007 Denver, Colorado

Flow Pattern Map Flow Pattern Map Govier G.W. and G.W. and Aziz Aziz, K: "The Flow of Complex Mixtures in , K: "The Flow of Complex Mixtures in Govier Pipes" Robert E. Drieger Drieger Publishing Co. Huntington, N. Y. Publishing Co. Huntington, N. Y. 1977 1977 Pipes" Robert E. Gas Velocity Impacts Gas Velocity Impacts 0.018 psi/ft Flow Regime Flow Regime V SG > 10 V SG > 10 1. Below Critical Velocity: Below Critical Velocity: 1. • V SL = 0 • V SL = 0 • Liquid Stays in Well • Liquid Stays in Well 2. Above Critical Velocity: Above Critical Velocity: 2. 0.433 psi/ft • VSG > 10 ft/sec • VSG > 10 ft/sec 0.08 psi/ft V SL V • High Gas Velocity • High Gas Velocity SL = = Well Lifts Liquid Out Well Lifts Liquid Out 0 0 Qg < Qc Qg < Qc 2007 Gas Well De-Liquification Workshop 8 Mar. 5 - 7, 2007 Denver, Colorado

Mist {Qg Mist { Qg > Qc} > Qc} Echometer Echometer Echometer S- -Curve Curve S S-Curve 0.08 psi/ft Q/A = Velocity Q/A = Velocity Q/A = Velocity Actual @ P&T @ P&T @ P&T Field Collected Data Points Determines Determines Determines Gaseous Gaseous Gaseous Liquid Loaded Liquid Loaded Liquid Loaded Column Column Column Gradient Gradient Gradient Below Below Below V SL = 0 V SL = 0 Liquid Level Liquid Level Liquid Level Loaded Loaded Qg < Qc < Qc Qg Qg < Qc < Qc Qg Qg < Qc 0.433 psi/ft V SL SL = 0 = 0 V V SL = 0 2007 Gas Well De-Liquification Workshop 9 Mar. 5 - 7, 2007 Denver, Colorado

Physical set-up on a Gas Well 2007 Gas Well De-Liquification Workshop 10 Mar. 5 - 7, 2007 Denver, Colorado

Gas Velocity Impacts Result of Gas Velocity Impacts Result of Fluid Level Fluid Level Acoustic Liquid Level Shot: Acoustic Liquid Level Shot: on Gas Well on Gas Well 1. Below Critical Velocity: Below Critical Velocity: 1. • Usually see liquid level • Usually see liquid level above bottom of Tubing above bottom of Tubing 2. Above Critical Velocity: Above Critical Velocity: 2. • May not see a liquid level • May not see a liquid level because liquid droplets because liquid droplets may fill tubing and absorb may fill tubing and absorb all energy from shot all energy from shot • May see bottom of tubing • May see bottom of tubing and/or perforations due to and/or perforations due to small amount of liquid small amount of liquid 2007 Gas Well De-Liquification Workshop 11 Mar. 5 - 7, 2007 Denver, Colorado

Mist {Qg Qg > Qc} (High Gas Velocity) > Qc} (High Gas Velocity) Mist { Imagine a fine mist cloud in Tubing Imagine a fine mist cloud in Tubing 1) Liquid Liquid being produced with the gas being produced with the gas 1) or condensing due to temperature or condensing due to temperature and pressure changes is uniformly uniformly and pressure changes is distributed in the wellbore. . distributed in the wellbore 2) Gas velocity is sufficient to Gas velocity is sufficient to 2) continuously carry liquid as a fine liquid as a fine continuously carry mist or small droplets to the surface or small droplets to the surface mist (Above Critical). (Above Critical). 3) Gas velocity is Gas velocity is sufficient to sufficient to 3) establish a relatively low and fairly fairly establish a relatively low and uniform flowing pressure gradient. . uniform flowing pressure gradient 2007 Gas Well De-Liquification Workshop 12 Mar. 5 - 7, 2007 Denver, Colorado

Procedure for Acquisition Procedure for Acquisition • Stop flow at the Surface • Acquire Fluid Level Measurement • Observe the depression of the gas/liquid interface and the increase in wellhead pressure. • Acquire Multiple Fluid Level Shots • Measurements should be taken (preferably at constant time intervals of about 3-5 minutes) • Use pressure at the gas/liquid interface to establish the gaseous column gradient • Extrapolate the PBHP 2007 Gas Well De-Liquification Workshop 13 Mar. 5 - 7, 2007 Denver, Colorado

Multi- -Shots Down Tubing Shots Down Tubing Multi Sec 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Mist {Qg Qg > Qc} > Qc} Mist { 316.2 mV (High Gas Velocity) (High Gas Velocity) Sec 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 316.2 mV Sec 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Fluid Level Measurements After Shut- -in in Fluid Level Measurements After Shut 316.2 mV Sec 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Shots taken at approximate 5 minute Shots taken at approximate 5 minute intervals intervals 316.2 mV Sec 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Should see Mist Gradient below Should see Mist Gradient below 100.0 mV Fluid Level Fluid Level Sec 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 100.0 mV Fluid level below tubing Fluid level below tubing 2007 Gas Well De-Liquification Workshop 14 Mar. 5 - 7, 2007 Denver, Colorado