This paper will discuss the Managed Pressure Directional Drilling fit-for-purpose solution deployed to meet the drilling challenges faced in 5 consecutive wells drilled in South Texas, USA. This innovative solution integrates a state-of-art Rotary Steerable System (RSS) with Managed Pressure Drilling (MPD) technology. Drilling hazards such as well control events, simultaneous kick-loss, and stuck pipe were mitigated, and an improved drilling performance with a reduction of NPT as compared to other directional drilling systems. The solution requires the integration of two highly technical disciplines, MPD and Directional Drilling. Hence, a Joint Operating & Reporting Procedure (JORP) and a defined communication protocol are crucial for effective execution. The solution is based on a rigorous Drilling Engineering process, including detailed offset wells analysis to deliver a comprehensive risk assessment & mitigation plan in collaboration with the Operator to tackle drilling hazards without compromising the directional drilling requirements. This paper will summarize the 5 wells operations, the drilling optimization results, and the lessons learned from an integrated services point of view in terms of deliverables that made the difference on this project and allowed the Operator to achieve their objectives. In particular, the effective communication protocol between the directional drilling services, MPD services, and rig contractors to ensure safe operational alignment.
Managed pressure cementing (MPC) is an important technique for primary cementing operations in wells with narrow pressure margins between the pore and fracture gradients. This paper presents the design considerations, methodology and results of two deepwater MPC operations conducted to cement production casing strings within a target operating window of approximately three tenths of a pound. Slurry densities commonly lead to high equivalent circulating density (ECD) levels during cementing operations. This condition, combined with mud weights conventionally designed to be above pore pressure, typically results in downhole pressures which approach or exceed the fracture limit. Commonly, operators implement strategies to mitigate undesired results during the cementing phase, however, in most cases the root cause of the problem cannot be adequately addressed by taking a conventional approach. Modern transient hydraulic modeling software permit the calculation of adequate surface pressure levels to control the annular pressure profile during the different stages of a cementing operation. Based on a predetermined annular pressure target, different variables can be designed to produce surface and downhole pressures within existing limits of a particular operation. This capability combined with modern managed pressure drilling (MPD) systems enables accurate control of the annular pressure profile during cementing and allows obtaining near constant bottomhole pressures (BHP) throughout the cement placement operation while using statically underbalanced mud columns. This case study presents an overview of the engineering process used to plan and design the managed pressure cementing operations on two wells and the results obtained. The results of this study demonstrate the advantages of using modern MPD systems over the conventional approach when it comes to primary cementing within narrow downhole pressure windows often encountered during deepwater drilling operations.
Multiple operators had attempted to conventionally drill wells in an area of south Texas targeting an over pressurized sand. A majority of them were unsuccessful showing a history of lost time events and poor well results related to kicks and losses. Information suggests little was known about the pore and fracture pressure gradients, and that uncertainties regarding real stratigraphic distribution were present, resulting in improper casing points and mud trends not in accordance with actual wells requirements. For these reasons, one operator decided to implement Managed Pressure Drilling (MPD) technology in order to safely and efficiently drill a well to the pay zone.The scope of the operation was a re-entry sidetrack on a vertical well that originally encountered well control and multiple mud losses events. The first interval was an 8-1/2 inch intermediate section to be cased with a 7 inch liner. The liner shoe was to be set approximately 80 feet above the over pressurized target sand. The second interval was a 6-1/8 inch production section targeting the well pay zone, to be cased with a 4-1/2 inch production casing. Both intervals were considered critical, the first one having depleted zones interbedded with gas bearing formations with a final depth immediate to abnormal gas pressures, and the second demanding accurate ECD management to avoid well control events, losses and formation damage, this of cardinal interest for the operator.The implementation of MPD enabled both intervals to be drilled to the planned target in a constant bottom hole pressure (CBHP) state safely and efficiently. The well was drilled near balanced to improve drilling efficiency and increase the ability to identify pore pressures. The annular pressure profile was adjusted instantly as the well dictated by means of MPD surface equipment avoiding kicks and losses. Continuous evaluation and monitoring of well behavior in real time allowed for pore pressure predictions, which were later used to plan proper kill mud weights, tripping/stripping procedures, and managed pressure cementing operations. Implementing MPD techniques and technology proved successful in enhancing safety and drilling efficiency on a well with many uncertainties and potential hazards. This paper will describe the planning and execution of a successful drilling operation on a high potential oil/gas producer well using MPD techniques in an area where others were unsuccessful.
This paper describes the underbalanced drilling (UBD) surface package used in the Saudi Aramco underbalanced coiled tubing drilling (UBCTD) project. A brief description on each item of this equipment is presented, as well as a description of the overall process flow. Moreover, the evolution and modification of the package throughout the period of the project and the optimization of the equipment to meet new challenges and to overcome some drilling hazards, such as erosion and high H2S levels, is discussed. The objective of the project is to drill reentry horizontal lateral sections in a hole size of 3⅝" with coil tubing (CT) using the UBD technique specifically the "Flow drilling" technique to increase the hydrocarbon’s productivity without damaging the formation, increasing the rate of penetration (ROP) and eliminating risk of losses or wellbore instability. The UBD surface equipment used for the UBCTD project was designed to handle maximum allowable rates to drill the well within safe limits. The equipment were selected and designed on the basis of historical data gathered from offset wells in the same specific field. The main focus in this paper will be on the lessons learned throughout the period of the project regarding the UBD surface equipment, which was specially built for this project.
This case study shows a cooperative implementation of managed pressure drilling (MPD), logging while drilling (LWD) and rotary steerable system (RSS) technologies to prevent non-productive time (NPT) while drilling through a section with a tight pressure window in a highly over-pressured reservoir in the US. Drilling risks were proactively reduced by providing real time data transmission for reservoir characterization and identification of critical well sections. The bottom hole assembly (BHA) was designed to be able to provide high quality measurements according with specific priorities in real time formation characterization and post mortem evaluation. The data transmission was also optimized to be able to monitor the performance of the rotary steerable system (RSS) as well as provide logging measurements that allowed decision making in real time. The implementation of MPD and the continuous monitoring of pressure while drilling (PWD) data allowed to adjust the downhole pressure profile to minimize the impact of drilling hazards by early detecting micro influxes and micro losses reducing considerably their size and impact to control them. Acquisition and transmission of high-quality logging while drilling data in real time allowed to identify the formations being drilled using Gamma Ray and resistivity logs anticipating the risk associated with each formation. The accurate identification of the pore pressure ramp, a consequence of using real-time MWD GR logging to correlate incoming formation tops with offset data, and the monitoring of the PWD data help to proactively respond to the imminent drilling hazards allowed to drill through these problematic sections using an underbalanced mud weight with the help of MPD which can adjust the pressure profile immediately reducing the risk of NPT. In addition to LWD and MPD technologies, the implementation and monitoring of RSS reduced the risk of downhole mechanical problems. Furthermore, acquired high-resolution sonic and density data from memory provided means to tie together the seismic data, in time, and LWD data, in depth, in order to make accurate predictions of incoming formations tops for future wells. This improved predictive capability to identify the depth range of the pore pressure ramp, while the correlative in-formation log signatures provided robust analysis of offset producing trends. Drilling scenarios that otherwise deemed unattainable due to the big potential for drilling hazards, can currently be tackled safely while also optimizing capital expenditure through the implementation and monitoring of reliable LWD, MPD and RSS systems. The designed BHA allowed reliable data acquisition and the use of MPD enabled the versatility of instantaneously adjusting the downhole pressure profile leading to a flawless drilling operation with reduced NPT associated to pressure-related issues.
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