State-of-the-Art Open Hole Tractor Enables Accurate Pressure Measurement in Horizontal Wells, Resulting in Significant Rig Time Saving

Abstract

In North Kuwait, formation evaluation in horizontal/highly deviated wells typically requires the use of Logging While Drilling (LWD) technology. In this paper, we will discuss how for the first time in Kuwait a state-of-the-art wireline open hole tractor has been successfully used to convey an advanced wireline pressure measurement in a horizontal well. Two wells will be discussed in this paper, the first was a short radius horizontal side track in the tight carbonate formation while the second is highly deviated well across sand/shale layers. Traditionally in horizontal wells, the pressure measurement is either run on drill pipe or LWD. Moreover, the formation tightness posed another challenge, as stabilized formation pressures can be difficult to achieve. To address the challenge of formation tightness and save rig time, a fast wireline pretest measurement tool allowing dynamic control of the pretest system would be conveyed on wireline using Open Hole tractor. A job simulation was conducted, based on the friction force and tool weight, to ensure the ability of conveying the tractor to the required depth in addition to the ultimate tractor drives number with tandem1 configuration. After gaining confidence and experience from the first well tractoring across tight consolidated carbonate, it was decided to go for open hole tractoring across less consolidated sand/shale layers in a highly deviated well (maximum deviation of 85deg). Both jobs were successfully executed as per plan. The tool was conveyed smoothly across the tight carbonate reservoir to the target depth of 10,030 ft MD at an average tractoring speed of 1800 ft/hr. The job was concluded with a cumulative tractoring footage of 3200 ft and an operating time of 12.5 hours, which resulted in more than 30 hours of rig time savings compared to other alternatives. The requested pressure program was achieved. Due to the pressure tool's low rate pretest capability, in addition to the flexible volume and pretest time options; stabilized formation pressure data could be acquired2,3. The precise depth control resulting from this conveyance method enabled accurate pressure profiling. Similarly, the second job was conveyed smoothly to the target depth. The combination of the advanced pressure measurement with a state-of-the-art open hole tractor1 conveyance method has proved to be an efficient and effective alternative to LWD and drill pipe in a challenging horizontal and highly deviated environments (the first job of its kind in the region). It resulted in acquiring accurate pressure data with significant rig time saving, and proved to be a cost effective solution contributing to an overall reduction in the well cost per barrel.