Mary Pickford

Geomechanics Insight Into Drilling of Deviated Wells Through Challenging Soft-hard Formations A Case Study from Godavari Onland, KG Basin Presenter: Rahul Talreja Geomechanics Engineer, Schlumberger Co-Authors: Koka Raj Kumar, Oil and Natural Gas Ltd Rajeev Ranjan Kumar, Amol Nakhle, Pratyush Tewari, Schlumberger

Introduction Primary Objective-Matsyapuri (Godavari clay petroleum system of KG Basin) Logistics, positional and Geographical complications, directional wells were drilled from a land site. Investigates three lost in hole incidents and other drilling related NPT

Well Profiles and Drilling Events 1st Stuck 2nd Stuck 3rd Stuck Well-B with stuck pipe incidents led to 3 LIH and multiple sidetracks

Drilling History Evaluation in Well-B They have maximum deviations of 60 and 48 and were drilled at azimuths of~150 and 108, respectively. In both the wells, severe wellbore instability issues were encountered in the Godavari clay and the Matsyapuri sandstone formation. Well A suffered approximately 16 days of non-productive time (NPT) whereas well B had 100 days of NPT .  Please check with details mentioned below; it seems well B had 3 LIH so it should hv higher NPT

Importance of Geomechanics Factors determining wellbore stability Pore pressure Mud Weight and casing policy* Stress magnitudes Stress Anisotropy direction Rock Mechanical Properties Wellbore trajectory* *Factor under human control s1 s2 s3 Stress regime: Thrust Tensile Failure -------------- Shear Failure

Offset Well Post-Drill Mechanical Earth Model for 12.25” Section Held up while lowering Logging Tool Over-gauged hole condition in shales corresponds to decrease in Rock Strength (UCS values)

Offset Well Post-Drill Mechanical Earth Model for 8.5” Section Differential Stuck while making connections due to overbalance in Sands (~0.3SG); Mud Weight was reduced from 1.3SG to 1.26SG Good Hole condition as indicated by the caliper corresponds to increase in Rock Strength (higher UCS values)

Collapse Pressure Variation with Deviation

Well-A: 1st Stuck Pipe Event in 12.25” Section ECD Block Position Hook Load Standpipe Pressure Depth Stuck Pipe DRILLING PARAMETERS, GPM-750, RPM-60-80, MUD PARAMETERS M.WT-1.10/40 PTK Plot Reciprocation…

Mud Weight used while drilling ~1.18SG-1.22SG Well-A: 2nd Stuck Pipe Event in 12.25” Section Deviation~60deg Mud Weight used while drilling ~1.18SG-1.22SG Mud Type changed to SOBM, GPM-850, RPM-100-120 Mud Weight -1.18 to 1.22 Matsyapuri Sandstone SOBM, GPM-850, RPM-100-120 and Mud Weight 1.22/80

Well-A: 2nd Stuck Pipe Event in 12.25” Section Matsyapuri Sandstone (a)-Drilling Parameters SOBM, GPM-850, RPM-100-120 and Mud Weight 1.22/80 (b)-Stuck pipe mechanism identification (c)-Basic Logs

Well-A: 3rd Stuck Pipe Event in 8.5” Section (a)-Drilling Parameters GPM-680 RPM 120 1..24/80 (b)-Stuck pipe mechanism identification (c)-Basic Logs

Hazards identification in the well planning phase Lessons Learnt Hazards identification in the well planning phase Optimum selection of mud weight and casing policy for drilling Drilling parameters in deviated wells (GPM and RPM) BHA Centralization Learnings Applied in Future Wells

Geomechanics is part of Engineering Planning. Without it, we are often like FIREMEN, Dealing with problems after the event of failure.

Thank You