A new evaluation method for wellbore quality

Accurate and comprehensive evaluation of wellbore quality is of great importance in drilling quality evaluation. The traditional explicit wellbore quality evaluation mostly leads to an evaluation report of single item, not considering the effect of casing running on wellbore quality. Based on analysis of IADC bit wear classification system and GCS (Glasgow Coma Score) method, and in conjunction with factors affecting the wellbore quality, a new wellbore quality evaluation method is presented — wellbore quality scorecard approach. This method will evaluate the wellbore quality through analyzing the torque and friction drag during the whole drilling process and will classify the wellbore quality; it is easy, reliable and flexible to use. The scorecard for wellbore quality is also helpful in comparing wellbore quality in different oilfields and blocks, and can be a useful tool for Party A drilling supervision and Party B wellbore quality control. Its application will also enhance the understanding of drilling crew on factors leading to low wellbore quality, so as to improve wellbore drilling and completion quality indirectly.