Severe drilling vibrations in top-hole section created unacceptable noise and risk. An AST was implemented to solve the problem.
Objectives
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.
FACTS
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
Results
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
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.
