| Popis: |
On several occasions during drilling, the drill string or in cases of liner job the liner string comes across an overall regressive environment. By regressive environments, the condition of the well bore returning to its unconditioned and in some cases unstable phase, is implied. The objective of this paper is to see how the regression impacts the circulating pressures in particular and how best to anticipate such conditions to optimize/modify the practices. The circulating pressures in deteriorated/reverted cases start showing spikes in the actual values well beyond the predicted models subsequent to same flow rates at the same depths. Such deviations in the actual vs theoretical values can pose severe complications for the drilling and liner jobs. These resultant complications however can be countered with the help of hydraulic mapping and gel envelope estimation in conjunction with optimized tripping and circulation practices for the respective operations to ameliorate the conditions. This paper explores the impact of regressive hole conditions ranging from constraints, operability, mechanical loads and fluid regimes. It builds upon that impact and delves into how best to utilize the tool of hydraulic mapping for smooth tripping and drilling operations in conjunction with the real time monitoring to define the operational envelopes. Delving into the dynamics of the hole conditions in regards to tripping and drilling operations across open hole, the paper seeks to build upon experience and reach an optimized mantle for tripping, drilling, circulation and conditioning operations in compromised hole conditions without any time delay or complication. During the life span of the well operations, the open hole well bore conditions of the wells become adverse to continuing onwards with the operations without at first conditioning or changing the downhole states altogether. This is the modus operandi for the majority of operations but in instances where the ambient impact is time sensitive or where the operations altogether are too complex and constrained for that to be done, the well conditions worsen, and the complications related to the ongoing operations increase manifold, rendering the operation in extreme cases unfeasible altogether. This likelihood can however be circumvented with the help of preventive intervention tools such as hydraulic mapping. There is no broad stroke solution to operational complications though, techniques and tools vary with each instance and are very case specific in both spectrum of definition and application. The most significant take away though, is how the incorporation of hydraulic mapping ensures the impending operational problems and complications are efficiently and specifically managed without any downtime or operational delay, on the fly. There are cases when the hydraulic and dynamic parameters have been mapped with upper limits built within the model yielding successful execution of operations against odds. In presence of rapid gelation or excessive gel breaking pressures against high differential formations, the practice of rotating prior to circulation or reciprocation prior to circulation are also determined with this tool. Real time operations monitoring also play a pivotal role in benchmarking and tracking the operational parameters of interest that are critical for operations. In order to achieve that however, there needs to be a composite model for the real time broomstick to be in place that reflects the overall picture of the open hole well bore. The hydraulic mapping technique requires minor inputs from the routine operational practices but forms an integral tool that can help execute operations effectively in jeopardized environments, against staggering odds without forfeiting any of the operational parameters or objectives. |
