ECD Reduction Tool R. K. Bansal, Brian Grayson, Jim Stanley Control Pressure Drilling & Testing Drilling Engineering Association, Fourth Quarter Meeting November 20, 2008 1
Presentation outline Description of the ECD Reduction Tool (ECD RT) Lab test results Field test results Forward plan Summary
ECD Reduction Tool (ECD RT) What? A downhole tool for reducing the equivalent circulating density (ECD), hence the bottomhole pressure, while drilling. Why? Wherever high ECD is a problem: You want to drill with a lighter mud to minimize chances for mud loss but you risk fluid influx when circulation stops. It is a common problem where difference between pore pressure and formation fracture pressure is small, or You want to use a heavier mud to improve wellbore stability but you can t due to increased risk of mud loss, such as in ERD wells (small difference between collapse pressure and formation fracture pressure). Where it is run? High in the drillstring, in the vertical section of the well close to surface.
Major benefits of ECD reduction Improved wellbore stability by tolerating higher static mud weights Extended hole intervals and reduced number of casing strings Reduced impact of uncertainty on casing setting depth by widening the usable PP/FG margin Reduced lost circulation and differential sticking
Description 8.20 ECD RT Modular design - 3 primary components Hydraulic turbine drive Annular pump Sealing element Total Length ~ 30 feet. Tool diameter 8.20 inch. Applicable in 9-5/8 (47# or lighter) and 10-3/4 casing pipes. TURBINE PUMP SEALS Normal circulation rate 500-550 gpm; 600 gpm max.
Operational Advantages Portable tool; Requires no rig modification Drill string component; Quick rig-up / rig down. Only a short trip of 7 stands is required to add the tool in drill string. For use on land and offshore applications Use for planned and or unanticipated problematic intervals of the well Does not impede mud pulse telemetry Does not affect normal drilling operations
Flow loop tests Performance characterization The effect of LCM in the drilling fluid The effect of reverse flow (bull heading) The effect of gas in the return fluid P1 P3 P2 Flow
Annulus pressure reduction as a function of circulation rate and mud weight 400 350 14.5 ppg Annulus Pressure Reduction, psi 300 250 200 150 100 50 16.5 ppg 17.8 ppg 19.2 ppg Water 10.4 ppg 0-50 0 100 200 300 400 500 600 Circulation rate, gpm
Projected ECD reduction versus depth 0 ECD Reduction, lb/gal 0.0 1.0 2.0 3.0 4.0 5.0 6.0 10.4 ppg Vertical depth, ft 5,000 10,000 15,000 20,000 25,000 12.5 ppg 14.5 ppg 16.5 ppg P ECD Reduction =.052*Depth Circulation rate: 525-550 gpm
Extra standpipe pressure (SPP) requirement 19.2 ppg 17.8 ppg 16.5 ppg 14.5 ppg 10.4 ppg Water 1200 1100 1000 Extra Standpipe Pressure, psi 900 800 700 600 500 400 300 200 100 0 0 100 200 300 400 500 600 Circulation rate, gpm
Full scale technology tests Primary Objectives 1.Quantify pressure reduction 2.Measure transient pressure spike at the start of rig pumps 3.Quantify Surge and Swab effects 4.Demonstrate compatibility with mud-pulse telemetry 5.Assess longevity of the tool at normal circulation rate P1 P2 Rig floor Flow line Ground ECDRT Bit Cement in lower two joints
ECD Reduction demonstrated in technology trial Circulation rate ECD
Field trials conducted Objectives Achievements Rig floor Quantify ECD reduction Evaluate operational procedures Demonstrated expected ECD reduction Did not impede normal drilling operation Cuttings flowed through the pump easily ECDRT Assess reliability Mud pulse telemetry worked normally Reliability proved to be a weakness. Maximum drilling achieved was 500-ft of 8.75 hole. Focus of recent development was to improve longevity and reliability. Drilling operation was monitored by standpipe pressure, hook load, real-time ECD and fluid return. Annular pressure sub
ECD reduction in Arkoma field trial Circulation Circulation rate rate Normal ECD ECD ECD Mud Weight
Forward Plan - Next Field Trial Plan going forward is to run a successful field trial and we are actively looking for an opportunity. Casing size 9-5/8 (47 lb/ft or lighter) or 10-3/4 Circulation rate between 475-550 gpm; mud type and weight do not matter. Ability to drill ahead 1500 to 2000 ft with the ECD RT located in the vertical hole. ECD RT starting location is 650-700 ft from surface. Instrumentation for real time display of downhole pressure, ECD and circulation rate. 6.75" 5.0" 6.75" 8.20" 6.75" 44" 355.6" (29' 7.6") UPPER GAGE CARRIER ECDRT 44" LOWER GAGE CARRIER
Summary ECD RT potentially offers significant benefits to drilling operations The concept of ECD RT has been proven in field trials The present design will function in 9-5/8 (47# or lighter) and 10-3/4 casing pipes and handle up to 600 gpm circulation rate Looking for additional field trial opportunity to prove reliability and longevity of the tool. Likely to develop other sizes subsequently.