| Title | ADVANCED DYNAMICS FEA MODELLING AS A NEW APPROACH TO IMPROVE GEOTHERMAL DRILLING PERFORMANCE IN INDONESIA |
|---|---|
| Authors | M.R.Y. Mardiana, B. Noviasta |
| Year | 2017 |
| Conference | New Zealand Geothermal Workshop |
| Keywords | FEA Modelling, Volcanic and Pyroclastic rocks, improvements, performance analysis |
| Abstract | With the downturn of the oil and gas business, geothermal projects in Indonesia are picking up, corresponding with the government’s commitment to increase geothermal utilization for generating electricity. In general, geothermal fields are located in the volcanic areas with hard formations like tuff and breccia. The unconfined compressive strength (UCS) vary from one field to another, in the range of 20 to more than 35 kpsi, with the volcanic rocks also having high abrasiveness and impact. Due to the limited drilling data available for geothermal areas, a “trial and error” approach usually becomes the method in selecting the bits and designing the BHA. However, this practice can lead to inefficient drilling, and generates higher costs in the end of the day as it doesn’t include the effects of the dynamics of the drill string. A comprehensive four dimensional, time-based Finite Element Analysis (FEA), run on a Unix platform, is applied for drilling optimization prior to the job. This simulation is much more accurate than static BHA modelling as all of the components are modelled in detail individually. The simulation modeled interaction between the cutting structure and formation drilled using rock mechanics derived in the lab. The result of the simulation are the drilling behavior of the all of the drill string components, including the vibrations, stress, torque, directional capability of the system, and even ROP prediction. In Indonesia’s geothermal drilling application, advanced FEA modelling has been used as a standard job planning method for bit/BHA optimization, directional capability prediction, and producing stable drilling parameter roadmap as an operation guideline. In one of the cases, only from bit optimization, this method can potentially save up to US$ 360,000 in drilling costs. With its capability, FEA modelling also has been utilized for post-job evaluation to review the drilling system and come up with better solution for the next campaign. |