Documentation and data collection of drilling operation is becoming more and more important in order to measure performance. Insufficient attention is paid to cost prognosis and furthermore on cost effectiveness. Costs are subject to many uncertainties in drilling and the industry misses a specific approach how to apply cost control when drilling a well. This makes the attempt to exactly allocate costs to special parts of the drilling activities very difficult. Bringing the means of cost control into the process of planning, executing and evaluating drilling operations is going to be one of the key issues for the ongoing economical success of drilling operations in the near and far future. Genesis Cost is a cost capturing software that drilling cost data has been collected with for more than ten years by a large operating company in the E&P business. The aim of the thesis is to provide a very broad theoretical basis and background information on drilling cost analysis and prognosis for the redevelopment and improvement of the cost capture software for the company. First an overview on costs in drilling from a technical angle is given. It is explained how drilling costs are incurred, what the most important drivers are and how operational decisions influence costs. The second chapter deals with the beginnings and more recent developments in literature on cost analysis and prognosis, which mainly focuses on the application of probabilistic methods to forecast time and cost of well drilling operations. The most popular is the Monte Carlo method, which is described in more detail. The literature only gives a general overview on cost estimation on a general level; therefore the third chapter takes a closer look at the actual daily operations in terms of costs. The collection, processing and analysis of cost data and the passage to defining performance indicators is described. Also, managerial or cost controlling aspects are taken into consideration. In the case study, a detailed picture on the current situation of the above mentioned company in terms of usage of Genesis Cost is given. The information is based on interviews with employees. Users of Genesis cost, their workflows and particularities of the company in terms of time and cost planning, reporting, cost accounting and analysis are described. An analysis has been performed with the existing cost data, which helps to familiarize with the cost data and its problems. The description of the status quo, together with results from the questionnaires, form the basis for changes, improvements and redevelopments of the software, which is the content of the next chapter. There is a discrepancy between the current literature and the actual application in the operating company, an outlook aims to fill that gap by suggesting a new method for cost planning, which will not be implemented.