Adaptive Well Construction Workflow developed from Offset Well Analysis of OMV Austria Deep Carbonate Wells
Research output: Research › Master's Thesis
From 2005 to 2008 OMV Exploration and Production GmbH developed the new sour gas field Strasshof in the Vienna Basin. During the Strasshof field development six wells and four sidetracks were drilled. All wells found hydrocarbons and indicated high to very high gas columns, but only two wells were completed as gas producers and their final production was way under the expectations. In 2013, the multidisciplinary project “Re-visit Deep Carbonates” was initiated to evaluate the Strasshof field to give recommendations for possible future activities. As part of the project, this thesis was initiated to analyze the wells drilled in the field development. The initial task of this thesis was to perform an in-depth offset well analysis with focus on mud systems, cementing techniques and drilling operations. Firstly, a review on offset well analysis and drilling performance measurement was performed and applied to the selected wells. Further the results were analyzed and an average non-productive time of 28% was determined for the wells drilled in Strasshof. As a next step, a detailed investigation on the non-productive time was performed. A plan-actual comparison of the drilling program showed that the well targets, with respect to time and cost, consequently failed due to significant scope changes during the drilling operations. Deepening the well beyond the planned depth, additional testing and logging were identified as the most important scope changes and their effect on the overall well performance was evaluated. The outcome of this evaluation was that almost 60% of the non-productive time, or 16% of the overall drilling campaign, was related to change of scope. One major finding of the offset-well analysis was that a significant amount of time was spent on unplanned or unscheduled events, because of scope changes during the execution phase of the drilling project. Especially during complex exploration and appraisal wells, like in Strasshof, many scope changes and unplanned events can be expected due to existing uncertainties. Therefore a review was performed on how to manage such scope changes and how management of change can be applied to well engineering. Finally, to handle scope changes better in future projects, an adaptive well construction workflow was developed based on the scope changes identified in the offset well analysis. This adaptive well construction workflow includes a proper planning process for possible changes as well as a process to manage undesired changes occurring in the execution phase of the well. The proposed workflow includes all actions, with focus on responsibilities and documentation, which should be taken in case of a scope change.
|Award date||4 Apr 2014|
|State||Published - 2014|