An Austrian oil company is drilling in Libya, Tunisia, Yemen and Iran using Chinese Drilling Contractors A and B at lower day rates than competition. The contractors are building new rigs and employ the necessary additional rig personal. This high number of new rig personal hired indicates that there may be less experienced personal available. This may influence the drilling contractor performance. In addition to personnel the equipment used has an important role when evaluating non-productive drilling time. To be able to quantify the performance there have been certain Key Performance Indicators (KPI) identified and defined, which are related to work procedures of the contractor. The data used is collected from Daily Drilling Reports. During data mining special focus was put on objectivity to guarantee comparability between the rigs. Furthermore, a contractor questionnaire for operator on-site personnel has been developed. In the third chapter the contractor costs are highlighted, with the help of data available from Libya. The drilling contractor cost for Chinese and competitor rigs in the same fields is investigated. The conclusion is that new Chinese rigs with new personal are not able to reach the level of performance of competitors. In countries like Yemen or Tunisia where A/B is active since a long time the performance is acceptable but still does not reach the high level of quality the operator is used to have on domestic drilling rigs..