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IMPROVING BOREHOLE INTEGRITY and STABILITY : DRILLING INCIDENTS and REMEDIES

IMPROVING BOREHOLE INTEGRITY and STABILITY : DRILLING INCIDENTS and REMEDIES. Presentation prepared before analysis of I.D.D.P./I.C.D.P. drilling conditions by Vincent MAURY. IMPROVING BOREHOLE INTEGRITY AND STABILITY : DRILLING INCIDENTS AND REMEDIES. __________.

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IMPROVING BOREHOLE INTEGRITY and STABILITY : DRILLING INCIDENTS and REMEDIES

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  1. IMPROVING BOREHOLE INTEGRITYand STABILITY : DRILLING INCIDENTS and REMEDIES Presentation prepared before analysis of I.D.D.P./I.C.D.P. drilling conditions by Vincent MAURY IDDP/ICDP WORK.1 15-17/03/02 V.MAURY / GEOMEC

  2. IMPROVING BOREHOLE INTEGRITY AND STABILITY : DRILLING INCIDENTS AND REMEDIES __________ 1) OBSERVATIONS AND DIAGNOSIS FROM PAST EXPERIENCE 2) EFFECT OF ISO/ANISOTROPIC LATERAL STRESS FIELD AND TEMPERATURE VARIATIONS ON STABILITY IN COMPACT OR LOW POROSITY/PERMEABILITY ROCKS 3) BOREHOLE INSTABILITY DUE TO LATERAL SHIFTS 4) REMEDIES PROPOSED AND TESTED [CASE HISTORIES] 5) NEW CONDITIONS RAISED BY I.D.D.P./I.C.D.P. . CONCLUSIONS : SUGGESTED/PROPOSED ACTIONS IDDP/ICDP WORK.1 15-17/03/02 V.MAURY / GEOMEC

  3. PAST EXPERIENCES AND SOURCES ___________________ DRILLING IN HP/HT CONDITIONS SPE 29428 HP/HT 200°C/ 115MPa at 5000 BOREHOLE INSTABILITY BY LATERAL SHIFTS DURING DRILLINGSPE 27492 Drill. & Compl. J. March 96 DURING HC PRODUCTIONSPE 48864 Dusseault, Bruno, Barrera • NEW BOREHOLE IMAGERY TOOLS • SPWLA June 99 (with Ph. PEZARD) EXPERTISE ON LONG-EXTENDED REACH WELLS Personnal confidential expertise North Sea DEEP OFF-SHORE DRILLING [DEPLETED RESERVOIRS] IDDP/ICDP WORK.1 15-17/03/02 V.MAURY / GEOMEC

  4. EFFECT OF TEMPERATURE ON BOREHOLE STABILITY __________________ COMPACT ROCKS : NIL POROSITY, TOTAL STRESS ~EFFECTIVE STRESS LOW POROSITY ROCKS : (EVEN POROSITY f ~ 1% !) : POSSIBLE EFFECTS OF FLUIDS TO CONSIDER EFFECTIVE STRESS DEFINED BY BIOT :Ds’= Ds-aDPp a, BIOT ’s COEFFICIENT 0 <f < few% : TRANSITION ZONE, CRITICAL, VERY LOW a, POORLY KNOWN HUGE IMPACT OF TEMPERATURE, INSTANTANEOUS OR DELAYED (EVEN 10-20°C) Dq = 1°C (heating) INDUCES # 0,5 to 1 MPa (COMPRESSION) LOW POROSITY ROCKS : Dq = 1°C (heating) INDUCES # 1 MPa Pore Pressure INCREASE IDDP/ICDP WORK.1 15-17/03/02 V.MAURY / GEOMEC

  5. EFFECT OF TEMPERATURE ON BOREHOLE STABILITY IDDP/ICDP WORK.1 15-17/03/02 V.MAURY / GEOMEC

  6. STRESS REGIMES AROUND WELLBORES (sr, sq,sl, SEE FIG. IN SPWLA) ___________ MODES OF ROCK RUPTURES : TRUE SHEAR : MOST COMMON in OIL/CIVIL ENGg EXTENSION MODE : [UNIAX. COMPR. TEST] TRUE TENSILE STRESS : [UNIAX. TENS. TEST] BOREHOLE MODES OF RUPTURE RUPTURE MODES OBSERVED IN O.D.P. RECALLS BOTH EXTENSION/TRUE TENSILE COMMENT : RUPTURES IN THE MOST DIFFICULT TRANSITION ZONES IDDP/ICDP WORK.1 15-17/03/02 V.MAURY / GEOMEC

  7. QUESTIONS ABOUT RUPTURE MODES (O.D.P. or BOREHOLES SUBMITTED TO VERY HIGH COOLING) __________________ POSSIBILITY OF MULTIPLE TRUE TENSILE MODES ? COMBINED TO ANISOTROPY OF IN SITU STRESS, INDICATOR OF STRESS ANISOTROPY DIRECTION ? ORIGIN : EXCESSIVE COOLING BUT ROLE OF TRANSIENT REGIME ? AFFECTS COMPACT ROCKS, BUT WHAT ABOUT LOW POROSITY ROCKS ? WHICH MECHANISM ABLE TO EXPLAIN PERFECT SHAPES OF RUPTURES ? IDDP/ICDP WORK.1 15-17/03/02 V.MAURY / GEOMEC

  8. BOREHOLE INSTABILITY DUE TO LATERAL SHIFT REACTIVATION ____________ BASIC MECHANISM : SEE FIG. in SPE DRILL. & COMPL. March 96 COOLING DECREASESsq and sl : IMPORTANT COMMENT : CONSEQUENCE : MAY INDUCE NEAR WELLBORE FRACTURING AND LATERAL SHIFT REACTIVATION ON ALL THE PREEXISTING FRACTURES PROVEN TO BE VERY ACTIVE MECHANISM IN HP/HT DRILLING (RESPONSIBLE FOR SERIOUS DRILLING INCIDENTS In NORTH SEA, COST, LOSS OF DIAMETER) REMEDIES : SEE REF. SPE March 96 IDDP/ICDP WORK.1 15-17/03/02 V.MAURY / GEOMEC

  9. REMEDIES PROPOSED AND USED [METHODS AND CASE HISTORIES] ___________ RECALL : TAKE INTO ACCOUNT THERMAL EFFECTS : ADJUST MUD WEIGHT (IF POSSIBLE) CONTROL OR MITIGATE THERMAL REGIMES : MUD CIRCULATION TIME, FLOW RATES, RECIPROCATION IN FACT, EXCESSIVE BOREHOLE WALLS TEMPERATURE VARIATIONS, BOTH IN HEATING AND COOLING MUD TEMPERATURE CONTROL : FOR « NORMAL » CONDITIONS : MUD COOLING SYSTEMS : SEE 25732 FOR SPECIAL CASES : MUD HEATING SYSTEMS (SALTS, EVAPORITES) IDDP/ICDP WORK.1 15-17/03/02 V.MAURY / GEOMEC

  10. REMEDIES PROPOSED METHODS (Ctd) __________ MUD DIVERTER SYSTEM (Ex-ELF Patent): PRINCIPLE : INTRODUCE PARTICULAR CIRCULATION SUB (SIMILAR TO SLIDING SLEEVES DEVICES) AT A SELECTED DEPTH TO DIVERT A FRACTION OF THE MUD FLOWRATE UPWARDS ADVANTAGES : DECREASE DOWNHOLE COOLING AND HYDRAULICS DECREASE UPHOLE HEATING, IMPROVES CUTTINGS TRANSPORT, CAN BE USED WITH MUD COOLER PRESENTLY CONTEMPLATED FOR SITUATIONS WITH EXCESSIVE DT : HP/HT, DEEP OFF-SHORE, LONG EXT. REACH, DEPLETED FIELD IDDP/ICDP WORK.1 15-17/03/02 V.MAURY / GEOMEC

  11. NEW QUESTIONS RAISED BY SPECIAL CONDITIONS IN IDDP/ICDP BOREHOLES __________ STRESS/TEMPERATURE DIFFERENT FROM HYDROCARBONS RESERVOIRS 1) EXTREME TEMPERATURE REGIMES AND VARIATIONS 2) VERY STIFF ROCKS : COMPACT OR VERY LOW POROSITIES ? HIGH SENSITIVITY TO THERMAL STRESSES 3) INCIDENCE OF TEMPERATURE ON ROCK BEHAVIOR LAW 4) SAME QUESTIONS APPLIED TO CORING CONDITIONS INCIDENCE ON CORE QUALITY INCIDENCE ON BOREHOLE STABILITY IDDP/ICDP WORK.1 15-17/03/02 V.MAURY / GEOMEC

  12. PROPOSED/SUGGESTED ACTIONS ____________ PURPOSES : 1) REDUCE/MITIGATE DRILLING INCIDENTS 2) IMPROVE : BOREHOLE STABILITY, WALLS CONDITIONS 3) IF POSSIBLE, IMPROVE CORING CONDITIONS AND CORE QUALITY METHOD : PRELIMINARY : COME-BACK TO DRILLERS/MUD ENGINEERS 1) DETAILED GEOMECHANICAL EVALUATION OF HT DRILLING/CORING OBSERVATIONS AND INCIDENTS 2) MAIN MECHANISMS OF INSTABILITY IDENTIFICATION 3) ACCORDING TO RESULTS, NUMERICAL MODELLING TRIALS : Ctd... IDDP/ICDP WORK.1 15-17/03/02 V.MAURY / GEOMEC

  13. PROPOSED/SUGGESTED ACTIONS (Ctd) ____________ 3) NUMERICAL MODELLING TRIALS : 1st STEP : ROUGH MODELS, THERMO-ELAST. LIN. 2d STEP (IF NECESSARY) : MORE ELABORATE BEHAVIOR LAW, TRANSIENT REGIME 3d STEP : CORING CONDITIONS MODELLING (?) 4) VALIDATION WITH FIELD/LOGS RESULTS 5) REMEDIES PROPOSAL AND EVALUATION WITH DRILLERS 6) FIELD TESTS, RESULTS SURVEY AND ITERATION ______________ IDDP/ICDP WORK.1 15-17/03/02 V.MAURY / GEOMEC

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