In the Piedmont region (Italy) the electronic ticketing system called BIP, is currently active across much of its territory, and thedata collected in the Province of Cuneo since the full activation of the system (2014) provide today a sound source ofinformation. Two different travel documents are available, travel passes and pay-per-use, with different validation rules: check-inonly for travel passes and check-in and check-out for pay-per-use. Data produced by this electronic ticketing system employingsmart cards allow to perform a detailed analysis of each user’s behaviour, and calculate time and space distributions of eachpassenger trip. In detail, data originating from smart card transactions allow to trace back the trip chains, establish journey originsand destinations, and produce a “travel diary” for each passenger. Based on this data, performance indicators (i.e. load factor) aswell as user mobility patterns and origin-destination matrices can be calculated in an automated and reliable way. This articlepresents a methodology for assessing the quality of the data collected when information about boarding and alighting stops isavailable from the (on board) validation system. It also presents an algorithm to assign a destination for each trip where only theboarding information is available. In the case study of the Province of Cuneo, it was found that 91% of the pay-per-use journeydata are reliable and can be used for further analysis, whereas with the use of the proposed algorithm it was possible to estimatethe destinations for 82% of the travel pass trips.DOI: http://dx.doi.org/10.4995/CIT2016.2016.1999
After 24 deepwater wells and almost 300,000 ft drilled with Managed Pressure Drilling (MPD) in the Gulf of Mexico (GOM) for the Operator Company during the last four years using a specific MPD service- provider technology, our experiences ascertaining operating windows in real-time are described in this paper. Including the first-ever Dynamic Pore Pressure Test (DPPT), inducing a planned influx and circulating it through the riser and MPD system, along with several Dynamic Formation Integrity Test or Dynamic Leak Off Test (DFIT/DLOT) performed at the shoe and TD to safely deliver the well, balancing strategy, and casing running/cementing efficiently. The results of these dynamic tests enabled the operator to make decisions in real-time with the primary goal of keeping safety as the priority during the campaign. The application of DPPT and DFIT/DLOT during the exploration well construction campaign in the deepwater GOM as part of the deliverables obtained from MPD to ascertain actual formation pressure limits in real-time has produced significant improvements in the safety standards for drilling specific hole sections with narrow pressure windows. Improvements were also seen in verifying accurate margins to trip with conventional well-balancing methods or using MPD for tripping out/in and running casing and cementing the sections using managed pressure procedures as an alternative to avoid a breach of the obtained margins. DPPT and DFIT/DLOT, in theory, and practice, are some of the essential benefits delivered by managed pressure technology. Both could radically influence verifying safety standards and margins during the well construction phase. This technical paper describes the justifications for performing a planned or required DPPT and DFIT/DLOT in several deepwater exploration wells that encountered challenges while crossing narrow operating windows, jeopardizing the well objectives and safety requirements. Also, discussing the US GOM regulatory requirements for approval, procedures, training, execution process, and final results impacted positive results when ascertaining the real pressure margins downhole and being available to drill, trip, and cement successfully using MPD technology.
The proposed well is an exploratory well where the formation pressures were estimated based on the experience in drilling offset wells in the area. The 8 3/8" and 5 7/8" hole sections, have a wide range of predicted pore pressure, indicating a considerable span of uncertainty in addition to other related conventional drilling problems as tight hole and gas influx. In previous wells drilled in the area, many drilling problems and wellbore stability issues were experienced. One of the possible cuases of the mechanical instability could be attributed to the large fluctuations in the bottom hole pressure that is intrinsic to conventional drilling practices. These fluctuations are originated from the stopping and starting of drilling fluid circulation during jointed pipe connections, specifically, they result from the fluctuation in the equivalent circulating density (ECD), which occurs when the pumps are turned on and off. This fluctuation could triger a kick-Loss scenario that increases the Non Productive Time (NPT). drilling-related flat time further indicate a necessity for a technology that enables more precise wellbore pressure management.Constant Bottom Hole Pressure (CBHP) which is variation of MPD, is applicable to avoid changes in ECD by applying appropriate levels of surface backpressure, a technique that maintains constant bottom-hole pressure during the complete drilling operation. The primary objective of drilling this well using the Managed Pressured Drilling technology was to reach the target depth with minimum drilling complication, avoid uncontrolled event by maintaining a constant bottom hole pressure and properly managing the well in case an underbalanced condition occurs while drilling the 8 3/8" and 5 7/8" hole sections.As with any advanced drilling technique, successful application of MPD technology required a detailed understanding of the potential benefits as well as limitations. This paper summarizes the process that was used to identify, plan, and implement MPD as a technology to drill the well to the target depth and prevent conventional. Planning and operational results are presented in this paper.
Managed Pressure Drilling (MPD) is an existing technology that is emerging in Deepwater drilling operations. This paper provides a case study from the Operator’s view, of preparing and deploying an MPD Surface Back Pressure (SBP) system for use in a shallow horizontal well with narrow drilling margins in 8,000ft water depth in the Gulf of Mexico. This paper will describe the engineering, preparations and operational challenges of deploying a Below Tension Ring (BTR) MPD system. The paper will also include information on the hazard assessments, Mud Gas Separator (MGS) considerations, training plan, deployment plan and results, and engagement with the regulator. The paper will present a case for the requirement of MPD for use in the narrow margin shallow horizontal wells, including an analysis of the required mud weights and surface back pressure to drill through narrow margins. It will also include a summary of best practices and lessons learned.
Narrow pore / fracture pressure gradient margins (operating window) is translated as a real drilling hazard scenario, where a slight change in the bottom hole pressure conditions can lead to an increase the Non Productive Time (NPT) due to the time spent in solve a possible fluid losses and/or gas kick situation, or even worst, dealing with occurrence of blowouts. In specific and non rare cases, deep formations with small gap between pore and fracture pressure are un-drillable with conventional drilling practices because the frictional losses pressure (difference between the dynamic and static pressure) is greater than the existent operating window. Constant Bottom Hole Pressure (CBHP), one of a number of variants of Managed Pressure Drilling (MPD) enables "walking the line" between pore and fracture pressure gradient. The objective is to drill with a fluid that bottom hole pressure is maintained constant, whether the fluid column is static or circulating. The loss of annulus flowing pressure when not circulating is counteracted by applied surface backpressure. The basic of Constant Bottom Hole Pressure (CBHP) methodology is to accurately determine the change in bottom hole pressure caused by dynamic effects and compensate with an equal change in annular wellhead pressure. The bottom hole temperature as well as the hydrostatic head of the drilling fluid column increases with the well depth and both parameters have opposing effect in the resultant static and dynamic equivalent density. An increase in the hydrostatic and dynamic pressures increases the equivalent fluid density due to compression but an increase in the temperature causes a reduction in the equivalent fluid density due to thermal expansion. Conventionally, these parameters considered together results in a cancellation of effects. In the reality, this assumption should be carefully reviewed. The effect of temperature in annular pressures, on a MPD CBHP operation through narrow operating windows, cannot be ignored due to the potential impact. Precise estimation of static and dynamic equivalent fluid densities is of essential importance for a successful MPD CBHP operation through narrow operating windows. Introduction The IADC has recently updated the definition of Managed Pressure Drilling (MPD) as follow: MPD is an adaptive drilling process used to precisely control the annular pressure profile throughout the wellbore. The objectives are to ascertain the downhole pressure environment limits and to manage the annular hydraulic pressure profile accordingly. MPD is intended to avoid continuous influx of formation fluids to the surface. Any influx incidental to the operation will be safely contained using an appropriate process.
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