WELLBORE STABILITY ANALYSIS OF GPK-4 SOULTZ-SOUSFORÊTS USING THE ESTIMATION METHOD OF MAXIMUM HORIZONTAL IN-SITU STRESS BASED ON BREAKOUT WIDTH DATA

• Main Author: Puteri Cahyarani, Alysia
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/67746
• Institution: Institut Teknologi Bandung

One of the form failures in borehole, the breakout, occurs due to a compression failure process when the maximum cylinder stress around the borehole increases. A very large value of the maximum horizontal will cause the borehole to be unstable. The borehole failure's form can estimate through the geomechanical model's parameters. In this study, the maximum horizontal stressing value calculated at the GPK-4 Soultz-Sous Forets well was based on breakout width of televiewer borehole data. This study also aimed to determine the effect of the estimated value of ???????????????????? on lithology and variations in rock strength values and to analyze these results with the safest mud pressure for drilling activities. The data used was the borehole televiewer (UBI Image) which was picked to obtain breakout width from drill hole GPK-4 in Soultz-sous-Forets, France, at TVD 4000 – 4800 meters, pore pressure, coefficient of internal rock friction, minimum horizontal stress values ,and vertical stresses according to the conditions in the well. Data processing was done by forward modeling with repeated formats for each breakout width to the depth. This study used the concept of the Mohr-Coulomb failure criteria as a reference. The results showed that by using rock strength parameters UCS 120 MPa and maximum breakout width at borehole GPK4 it is known that the ???????????????????? value ranges from 22.15 MPa/km – 28.08 MPa/km. As for the modus breakout width data, it is known that the ???????????????????? value ranges from 21.34 MPa/km – 23.02 MPa/km. Based on the breakout mode width data, the drill hole is classified as stable (safe) for drilling activities with UCS 120 conditions at an inclination of 30° relative to NE-SW. While the maximum breakout width data is classified as unstable except for the lithological contact at a depth of 4633 m. The addition mud pressure can reduce the width of the breakout, with the addition mud pressure up to 10 MPa, a stable borehole can be obtained with wbo<60° except for the maximum breakout width with two-mica granite lithology at a depth of 4804 meters.