Severe drilling vibrations in top-hole section created unacceptable noise and risk. An AST was implemented to solve the problem.
Tool
9 1/2” XD-AST 9” HB-AST
Client
RAG
Country
Austria
Rig
RAG E200
Section
17 ½”
BHA
Rock-bit and packed rotary BHA
Objective
Reducing surface
vibrations at source
Severe surface vibrations and noise were significant operational and environmental concerns when drilling conglomerates and marl in the 17 ½” top hole section with a roller cone bit in the Austrian part of the Molasse Basin. To improve on the situation the major operator in the area, RAG decided to run an Anti Stick-slip Tool. The BHA was not changed from previous wells other than including the AST. This gave a good basis for pinpointing the effect from the tool.
Results
Less vibration,
higher ROP
The AST tools were run in multiple wells with the same good results; the vibrations were significantly reduced and the ROP increased compared to offset wells;
Value
Quieter drilling,
faster delivery
By reducing surface vibrations, the noise level was reduced to a level that is acceptable when drilling in a residential area and damage to surface equipment was eliminated. Furthermore, drilling time was reduced and the sections were drilled without tripping.
