Successful Use of Real Time Dynamic Flow Modelling to Control a Very Challenging Managed Pressure Drilling Operation in the North Sea

113

An essential part of an automated managed-pressure-drilling (MPD) control system is the hydraulics model, which, in many cases, is the limiting factor for achievable accuracy of the system. Much effort, therefore, has been put into developing advanced hydraulics models that capture all aspects of the drilling-fluid hydraulics. However, a main drawback is the resulting complexity of these models, which require expert knowledge to set up and calibrate, making it a high-end solution.In practice, much of the complexity does not contribute to improvement of the overall accuracy of the pressure estimate simply because conditions in the well change during MPD operations and there are not enough measurements to keep all of the parameters of an advanced model calibrated.We will demonstrate that a simplified hydraulics model based on basic fluid dynamics is able to capture the dominating hydraulics of an MPD system. Furthermore, we will demonstrate that, by applying algorithms for online parameter estimation similar to those used in advanced control systems in the automotive and aerospace industry, the model can be calibrated automatically by use of existing measurements to achieve a level of accuracy comparable with that of a calibrated advanced hydraulics model. The results are demonstrated using field data from MPD operations in the North Sea and dedicated experiments obtained at a full-scale drilling rig in Stavanger.

Section: Motivationmentioning

confidence: 99%

“…These models are able to reproduce a wide range of drilling-specific effects to an impressingly high degree of detail. Real-time versions of these models have also been used in MPD operations-both offline and online [see, for example, Eck-Olsen et al (2005) and Bjørkevoll et al (2008Bjørkevoll et al ( , 2010]. …”

Section: Introductionmentioning

confidence: 99%

Simplified Hydraulics Model Used for Intelligent Estimation of Downhole Pressure for a Managed-Pressure-Drilling Control System

Kaasa¹,

Stamnes²,

Aamo³

et al. 2012

113

“…The purpose of MPD solutions is to maintain the downhole pressure within the geopressure limits, but for technical reasons they are in fact controlling the downhole pressure at a particular depth in the well. There are several techniques available to achieve this goal: annular backpressure MPD (Bjørkevold et al 2010;Godhavn 2010), low-annulus-level MPD (Fossli and Hendriks 2008), dual-gradient MPD (Breyholtz et al 2011), and so forth. However, the controllability of the downhole pressure at a particular depth in the well is dependent on the compressibility of the drilling fluid with respect to the length of the drillstring and wellbore, the relative velocity of the mud and drillstring compared with the wellbore, the actual downhole conditions (i.e., in-situ drilling-fluid properties, annulus restrictions, and enlargements caused by cuttings or hole collapse), and the reaction time of the control technique itself.…”

Section: Drilling-automation Systemsmentioning

confidence: 99%

Toward Drilling Automation: On the Necessity of Using Sensors That Relate to Physical Models

Cayeux

Daireaux

Dvergsnes

et al. 2014

Current topside and downhole instrumentation at the wellsite has been developed to manually conduct drilling operations. The emergence of automatic drilling-analysis software shows the limitations of today's measurement capabilities. It is therefore time to analyze the requirements for on-site instrumentation to implement new, efficient drilling-automation technologies.On one hand, drilling is facing more and more difficult conditions with narrow geopressure windows, deepwater, or high-pressure/high-temperature (HP/HT) conditions. On the other hand, unconventional hydrocarbon reserves may require a considerable amount of wells to be profitable. Drilling automation, by means of smart safeguards, automatic safety triggers, managed-pressure drilling (MPD), and ultimately complete or semiautonomous drilling rigs, can provide the solution to safely construct wells in these challenging settings.The common denominator for the vast majority of drilling-automation solutions is the use of physical models of the drilling process in the form of heat-transfer, mechanical, and hydraulic models. By analyzing the requirements of those models for necessary boundary conditions, it is possible to derive which measurements should be made both at surface and downhole to obtain stable and accurate calculations. This analysis also provides a way to estimate the necessary accuracy of the boundary conditions to ensure reaching the target control tolerance.By use of the boundary-condition analysis, it is possible to derive precisely which measurements should be performed and where they should be performed. As a result, a typical organization of sensors that is compatible with the implementation of drilling-automation solutions is derived.

“…When using an MPD solution that is based on backpressure (Bjørkevold et al 2010), the effect of the mud weight is combined with an additional pressure at the surface (Fig. When using an MPD solution that is based on backpressure (Bjørkevold et al 2010), the effect of the mud weight is combined with an additional pressure at the surface (Fig.…”

Section: The Wellbore Simulatormentioning

confidence: 99%

Advanced Drilling Simulation Environment for Testing New Drilling Automation Techniques and Practices

Cayeux

Daireaux

Dvergsnes

et al. 2012

Newly developed drilling automation systems locate a computer interface between commands issued by the driller and instructions transmitted to the drilling machinery. Such functions are capable of faster and more precise control than can be achieved by an unaided operator and thus can help drilling within narrow margins. To ensure that these systems work properly in all circumstances, an advanced drilling simulator has been developed to enable testing under a wide range of simulated conditions.The environment described in this paper uses hardware in the loop (HIL) simulation to verify that the automation techniques being tested respond correctly in real time. Rigorously validated physical models of the drilling process simulate the response of the well to the commands given to the drilling machines. Abnormal drilling conditions (e.g., packoffs, kicks) and equipment or machine-related problems (e.g., plugged nozzles, power shortage) are convincingly recreated.The drilling simulator models the behavior of surface equipment such as the activation of gate valves to line up different pits or the flow in the mud return. It simulates changes in the drilling fluid properties when mixing additives to the mud. It is therefore possible to focus training sessions on cooperation between different groups at the wellsite. This is particularly useful when planning the introduction of drilling automation that involves new work procedures as a result of automation and adaptation of the drilling team to a new operational environment.Drilling operations are becoming more and more complex. Automation has the potential to provide large improvements in efficiency and safety, but automation technologies must be implemented correctly at the workplace. Just as the aviation industry has used simulated environments for decades, drilling simulation environments are the key to the safe and successful implementation of drilling automation and the development of crew skills to face future challenges.