SAND PRODUCTION ON WATER INJECTORS JUST HOW BAD
SAND PRODUCTION ON WATER INJECTORS: JUST HOW BAD CAN IT GET ? F. J. Santarelli (ORMIS), E. Skomedal, P. Markestad, H. Nasvig and H. I. Berge (Statoil) Paper SPE 47329
STRUCTURE • INTRODUCTION • HISTORY OF SUBSEA WELLS • ROCK MECHANICS CONDITIONS • CROSS FLOW • PARTICLE SETTLING DURING SHUT IN PERIODS • SUDDEN WELL LOSSES • FIELD EVIDENCE OF WATER HAMMER AND SAND LIQUEFACTION • OPERATIONAL CONSEQUENCES • CONCLUSION Paper SPE 47329
INTRODUCTION SAND PRODUCTION RISK IS HIGHEST ON PRODUCERS • Flow Gradient • Bringing Sand to Surface SAND PRODUCTION ON PRODUCERS IS WELL STUDIED (and understood) ALMOST NOTHING PUBLISHED ABOUT INJECTORS FIELD CASE OF SAND PRODUCTION ON INJECTORS WITH CATASTROPHIC PRACTICAL CONSEQUENCES Paper SPE 47329
WELL HISTORY COMPLETION FIRST BACK PRODUCTION INJECTIVITY SECOND BACK PRODUCTION INJECTIVITY WORK OVER INJECTIVITY (? ) OCT. 95 Paper SPE 47329 JAN. 96 MAY 96 Good Injectivity Recovery No Effect or Worsening SEP. 96 Important Sand Fills Often Above Top Perforation
WELL HISTORY 2 Logarithm of Pressure Ratio 1, 8 Near By Fault Regime 1, 6 1, 4 1, 2 1 st Shut In 2 nd Shut In 1 0, 8 Near Wellbore Regime 0, 6 0, 4 0, 2 0 0 Paper SPE 47329 10 20 30 40 50 60 Time (min) 70 5 SUDDEN WELL LOSSES 80 90 100
ROCK MECHANICS CONDITIONS 10 bar < UCS < 80 bar FAILURE DURING SHUT INS ROCK AROUND CASING IS FAILED AND CAN PRODUCE SAND Paper SPE 47329
CROSS FLOW Upper F 3 Lower F 3 F 1 6507/7 -B-3 H Time (hours) 0, 0001 0, 1 1 10 100 500 300 200 100 0 -100 -200 -300 -400 Paper SPE 47329 CROSS FLOW FROM LOW k TO HIGH k Injected Rate (m 3/d) 400
PARTICLE SETTLING 6507/7 -B-3 H 0. 5 hours 6 hours % of Particles in Suspension 80, 00 70, 00 60, 00 50, 00 40, 00 30, 00 20, 00 10, 00 3240 3250 3260 3270 3280 3290 3300 Depth (m MD-RKB) Paper SPE 47329 PARTICLES MAY REMAIN IN SUSPENSION
PARTICLE SETTLING Formation Sand Low Permeability Smaller Grains Reinjected High Permeability Perforated Interval Coarser Grains Settled in Rat Hole Perforated Interval Rat Hole CROSS FLOW Paper SPE 47329 Rat Hole RE-START INJECTION
PARTICLE SETTLING 6507/7 -B-3 H I. I. m 3/bar/d Rate m 3/h 400, 00 350, 00 300, 00 250, 00 200, 00 150, 00 100, 00 50, 00 31. Oct. 95 01. Mar. 96 01. Jul. 96 31. Oct. 96 02. Mar. 97 31. Dec. 95 01. May. 96 31. Aug. 96 31. Dec. 96 Paper SPE 47329
SUDDEN WELL LOSSES Open Valve Pipe Fluid Layer v BEFORE CLOSURE Closed Valve Pipe Fluid Layer v v v=0 Overpressurised Layers AFTER CLOSURE Depressurised Layers
SUDDEN WELL LOSSES At the Valve Time Closure 2 th pf Closure th 2 th Time p Paper SPE 47329 At the Rock Face
WATER HAMMER AND SAND LIQUEFACTION Paper SPE 47329
WATER HAMMER AND SAND LIQUEFACTION Paper SPE 47329
WATER HAMMER AND SAND LIQUEFACTION Top Sand Fill Top Perforation Sand Movement Liquefied Zone DURING INJECTION Paper SPE 47329 WELL CLEN UP “Emptied” Liquefied Zone DURING PRODUCTION
OPERATIONAL CONSEQUENCES TWO MECHANISMS LED TO DRAMATIC INJECTIVITY LOSSES THE FIELD WENT OFF PLATEAU AS A CONSEQUENCE THE SHUT DOWN PROCEDURES HAVE BEEN CHANGED THE REOPENING OF THE WELLS IS ALWAYS DELAYED INJECTIVITY LOSSES HAVE DISAPPEARED THE FIELD IS BACK TO PLATEAU Paper SPE 47329
CONCLUSIONS SAND PRODUCTION ON INJECTORS IS OFTEN IGNORED YET FIELD CASES SHOW IT CAN HAVE DRAMATIC CONSEQUENCES (FIELD OFF PLATEAU) TWO MECHANISMS OF INJECTIVITY LOSSES HAVE BEEN IDENTIFIED: • Sand Produced by Cross Flow is Reinjected and Plugs Perforation Tunnels • Pressure Wave Liquefy Sand in the Perforated Interval PROCESS MODIFICATION ARE REQUIRED SOMETIMES SAND CONTROL IS COMPULSARY Paper SPE 47329
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