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Yekta, Kaveh (Essential Energy Services) | Stang, Benjamin (Essential Energy Services) | Hilling, Scott (Shell Canada Limited) | Schwartz, Chris (Shell Canada Limited) | Cheung, Bettina (Shell Canada Limited) | Elliott, Kevin J. (NOV Quality Tubing) | Williams, Cedric D. (NOV Quality Tubing)
The Shell Canada Fox Creek asset is located in West Central Alberta and has development activities focused on the Duvernay reservoir. Efficient, horizontal, plug and perf wells, are key to delivering economic production from this unconventional light tight oil play. Unlocking more acreage per well, through the application of longer laterals, contribute significantly to CAPEX reduction. Although intervention-less completions are a future aspiration, well intervention is still required for plug removal to assure stimulated intervals are able to flow unimpeded. A number of initiatives were actioned collaboratively across service providers and well delivery teams, to support well intervention to the limits of Coiled Tubing (CT) milling operations on the FC734 D well.
Considering the length of this well (7349mMD), a new string design was required to achieve the maximum depth as well as to provide the required WOB for milling operations. Horizontal wells with long laterals, such as in this case, require heavy wall tubing in the vertical section to beyond the heel into the lateral. Using a special custom-designed transition section in the Coiled Tubing string enabled the CT to reach the maximum depth. Utilizing fluid rheology application provided a means to keep track of Reynold's number in a real-time fashion to ensure turbulent flow regime downhole, and in turn, to optimize solid transport as well as chemical consumptions. The application of fluid rheology resulted in wiperless milling operation in the extended reach applications. The flagship unit in the fleet was utilized in this operation. Generation four of the CT unit was designed in such a way that it can carry up to 8,345m of 60.3mm(2-3/8in) CT pipe. There were different technological advancements, industry-leading features, and custom engineering used in the design of this unit. Such features include customized PLC automation, user-friendly remote operation, advanced informative human-machine interface displays, and real-time data acquisition and data storage from vast arrays of operational sensors.
There is a twofold impact on the field development plan when the total measured depth (MD) was increased. First, this enables the operator to increase step out/generate drilling optimized trajectories without sacrificing lateral length. Second, the 400m/well increase in MD when applied principally to the lateral length netted an average increase of 250m/lateral in the subject area and reduced the well count by 4% (pad count reduction of 10%).
The synergy impact of utilizing several variables resulted in successful operations. Those variables are field development plan (well design), custom string design (CT reach), real-time fluid rheology (solid transport), and the application of an advanced CT unit (equipment advancement). The successful delivery of the FC734 D well demonstrated the value of collaborative design and best practice sharing and has extended the technical design limit of well lengths across Shell Unconventional.
Ryan, M. (Baker Hughes, a GE Company) | Gohari, K. (Baker Hughes, a GE Company) | Bilic, J. (Baker Hughes, a GE Company) | Livescu, S. (Baker Hughes, a GE Company) | Lindsey, B. J. (Baker Hughes, a GE Company) | Johnson, A. (Murphy Oil Company) | Baird, J. (Murphy Oil Company)
Development of unconventional reservoirs in North America has increased significantly over the past decade. The increased activity in this space has provided significant data with respect to through-tubing drillouts which had previously not been attainable. This paper is focused on using the field data from the Montney and Duvernay formations along with laboratory data and numerical modeling to understand the hole cleanout associated with through-tubing drillouts of frac plugs.
Initially, an extensive full-scale flow loop laboratory testing program was conducted to obtain data on debris transportation for hole cleanout during through-tubing applications. The testing was conducted on various coiled tubing (CT)-production tubing configurations using various solid particles. The laboratory data was used to develop empirical correlations needed for a transient debris transport model. This model was then used for frac plug drillouts to ensure successful hole cleaning in actual field applications. Computational fluid dynamics (CFD) modelling was also used to further understand and quantify the differences between the laboratory data, field data and transient debris transport model results.
The objective of the work conducted was to gain a better understanding of debris transport and validate the empirical modelling approach developed for hole cleaning. The validation process was conducted in several stages. The first stage was to validate the laboratory data against the Montney and Duvernay field data. The second stage was to verify the results obtained from the empirical model against the results obtained from a computational fluid dynamic model. The results from both modelling approaches were lastly compared to the field data. All these results challenge the current industry's understanding and best practices for through-tubing drillouts in the Montney and Duvernay formations. With the contentious increase of lateral lengths and higher stage counts, the process of drilling out frac plugs has become more complex. This study explicitly benefits all operators in their ever-increasing need to understand their frac plug drillout operations to ensure efficient, cost effective, and most importantly, consistent and repeatable results.
While efficient results for frac plug drillout operations have been accomplished to date, the on-going feedback from the field has been the requirement to produce repeatable drillouts. This paper is the first to show a holistic approach for obtaining a transient debris transport model used for through-tubing drillouts of frac plugs. The novelty also consists of the transient debris transport model validation through laboratory data and actual Montney and Duvernay field data.
This article, written by JPT Technology Editor Judy Feder, contains highlights of paper SPE 191689, “Factory-Model Approach for Successful Coil-Tubing-Unit Drillout Operations in Unconventional Wells,” by Jesus Barraza, SPE, and Chris Champeaux, SPE, Chevron; Heath Myatt, SPE, and Kyle Lamon, C&J Energy Services; Ryan Bowland, Spartan Energy Services; Troy Bishop, SPE, and Jerry Noles, SPE, Coil Chem; and Rocky Garlow, RGC Consulting, prepared for presentation at the 2019 SPE Hydraulic Fracturing Technology Conference and Exhibition, The Woodlands, Texas, USA, 5–7 February. The paper has not been peer reviewed.
As drilling and fracturing operations improve, there is a need to adapt current coiled-tubing (CT) drillout processes to a more fit-for-purpose approach applicable in any area, regardless of lateral length, number of plugs, and reservoir target. This paper presents a factory-model approach to improving CT drillout performance that has been used successfully for more than 3 years and has become standard practice. The paper includes detailed discussion of the methodology used to create a successful, repeatable, and operationally safe process; field case studies and results; and engineering, design, and implementation of new technologies to improve the process.
CT practices have become increasingly effective in plug drillout operations by reducing the operational cost, environmental exposure, and time to production. Techniques for no-wiper or short trips and plug milling, added benefits from extended-reach bottomhole assemblies (BHAs), and improved fluid-system monitoring methods have helped enhance overall performance. However, there are still components within each of these techniques that can be evaluated.
Background and Methodology Results of a thorough evaluation of the CT drillout process revealed that the factors with the greatest influence on improving performance included the following:
Wellbore trajectory is an important factor because it has a major effect on the ability of a CT unit to reach plug-back total depth. High tortuosity in the lateral section can cause plug parts and sand to settle on the low side of the wellbore, making adequate cleaning of the hole by increasing overall friction difficult.
Proper plug type and design serve two purposes: to provide a barrier between stages during hydraulic-fracturing operations and to be easily removed from the wellbore during drillout. Ideally, a fully composite plug should be selected because the lower specific gravity of the material aids in removal.
The proper CT size can lead to a more-successful drillout because it allows for higher pump rates, leading to better hole cleaning. Additionally, larger outer-diameter CT (23/8 in. or greater) ensures sufficient weight on bit (WOB) in the toe of longer laterals to reduce friction pressure and protect against helical buckling.
With the objective of increasing productivity and achieving an economically sustainable development of the non-conventional reservoirs in Argentina, the oil and gas (O&G) energy companies are focused on drilling horizontal wells with lateral extensions between 2500 m (8,200 ft) to 3000 m (9,840 ft) in length. In order to produce commercial volumes of hydrocarbons, it is mandatory to fracture-stimulate multiple zones.
The "plug and perf" method continues to be the most common completion technique in the field. Once the stimulation is completed, a coiled tubing (CT) milling operation is undertaken to remove the frac plugs. Critical to achieving a successful operation is reaching total depth (TD) in the well with the coiled tubing. The precise determination of the operational coefficient of friction (CoF) between the coiled tubing string and the production casing, could be the difference between failure and success, affecting both the technical and economical results of the project.
The goal of this paper is to share the lessons learned after more than forty extended reach operations and the experience earned on the utilization of real time simulations to define both, the tensile load exerted for an extended reach tool and the coefficient of friction found during coiled tubing operations. Also demonstrate, by analyzing real life applications, how the implementation of this technology and new working methodology, allows to anticipate deviations with respect to the "normal" values of friction, achieve a better understanding of the influence of solids in the completion to the coefficient of friction and obtain a more efficient use of the metal-metal lubricant utilized during the milling operations.
Barraza, Jesus (Chevron North America E&P) | Champeaux, Chris (Chevron North America E&P) | Myatt, Heath (C&J Energy Services) | Lamon, Kyle (C&J Energy Services) | Bowland, Ryan (Spartan Energy Services) | Bishop, Troy (Coil Chem LLC) | Noles, Jerry (Coil Chem LLC) | Garlow, Rocky (RGC Consulting LLC)
As drilling and fracturing operations improve and wells have longer laterals, there is a need to adapt current Coil Tubing Unit Drillout (CTUDO) process to be more fit-for-purpose approach applicable in any area, regardless of lateral length, number of plugs, and reservoir target. This paper presents the CTUDO methodology developed and implemented with case study results on the successful engineering design and implementation of new technologies to improve performance and eliminate large nonproductive time events, via the utilization of a successful, repeatable, and operationally safe process.
A thorough evaluation of the CTUDO process was conducted to gain a better understanding of the critical factors that provided the greatest influence on improving performance. The results indicated that the main influencing factors were: wellbore trajectory, plug type, coil tubing size, bottom hole assembly (BHA) selection, fluid rheology QA/QC, real-time modeling, and communication. Rather than instituting and optimizing the critical factors all at once, a piece-by-piece road map was created. Over a five-month trial period, the factors were fully implemented and analyzed. Once the methodology was validated with predictable, repeatable, and successful consistent outcomes, it became the new standard for CTUDO's.
Full implementation of this Factory Model CTUDO methodology has been successfully used for over three years and continues to be the standard process. The well performance impact realized by optimizing the main factors, along with other technological advancements has been substantial. Appropriate engineering design led to better understanding the fluid rheology system and optimal chemical usage and dosage during CTUDO's. Coupled with proper CTU size and BHA optimization, pump rate capability and annular velocity are optimized, while minimizing plug debris size, aided in hole cleaning, which lead to greater efficiency. The use of data analytics to identify trends in downhole tool data, used in conjunction with real-time data allowed for procedure optimization. Operational enhancements include removing planned short trips (ST) and effectively eliminating stuck CTU events. Since the inception of this methodology 320+ horizontal wells ranging from 5,000′ to 10,000′+ have been successfully completed, with well plug counts ranging from 19 to 102. Average time savings is shown to be 66%, and average cost savings 61%. In addition, the process has provided additional cost savings benefits and reduced Put-On-Production (POP) cycle times by eliminating the need of dedicated post drillout flowback.
This paper details the utilization of a simple, effective method for successfully executing and improving performance on CTUDO's. This paper also incorporates lessons learned and best practices from field execution, real-time data analysis and interpretation, and technology implementation. Furthermore, this methodology is designed to be a plug-and-play system, with minimal or no modifications needed to be applied in any unconventional basin across the world.
More than 20 years ago, the first e-line coiled tubing drilling (CTD) systems were introduced. Since then, the technology has evolved and proven to be an efficient, economic means of enabling additional production from aging oil and gas fields. These systems are now established as a standard, viable solution for re-entry drilling in a variety of maturing fields and applications. Corresponding technologies and procedures were developed, and continuously improved.
Utilizing project data from more than 20 years of operational experience, this paper describes the progression from the first e-line CTD bottom hole assembly (BHA) applications in Europe through to today's continuous operations in several areas worldwide. It presents the technology changes and procedural adjustments that were necessary to address new challenges related to extending the economic life and improving the production of mature fields by economically accessing stranded reserves, and includes:
Wellbore design changes from single re-entry to multilateral wells, along with the envelope extension from pure geometric wellbore placement according to plan, to real-time reservoir navigation utilizing geo and bio-steering services.
Introduction of special applications such as precise kick-off from vertical, dual casing exits and extended reach drilling (ERD) with CT technology.
Progression from overbalanced drilling operations to full underbalanced (UB) applications, with nitrogen injection through the CT string and the requirement to manage production while drilling.
Equipment development to enable safe pressure deployment of the drilling BHA, enabling a move from conventional tower set-ups to dedicated highly mobile coiled tubing rigs.
Continual improvements of technology and steady implementation of new developments in many aspects of CTD technology were the result of innovative re-entry projects executed worldwide. To achieve the necessary efficiency and economic goals, improvements and new technology developments occurred in the downhole BHA technology, casing exit equipment, surface equipment, rig and other associated systems. Simultaneously, processes and procedures were also optimized with new ones introduced to adapt for changing environments and observed challenges.
Based on worldwide CTD experience, the trend of technology developments and continuous improvement will continue. The goal is to further drive project efficiencies and economics, enabling the life of maturing fields to be extended, deferring abandonment and improving ultimate recovery.
Narcizo, O. Melo (PEMEX) | Aguilar, A. Martinez (PEMEX) | Mendo, A. Rosas (PEMEX) | Gordillo, J. C. (PEMEX) | Ramondenc, P. (Schlumberger) | Burgos, R. (Schlumberger) | Basurto, J. R. Cervantes (Schlumberger) | Rodriguez, F. L. (Schlumberger)
An innovative approach to underbalanced perforating in horizontal and highly deviated wells uses a new perforating head specifically developed to leverage the conveyance and real-time telemetry capabilities of coiled tubing (CT) equipped with fiber optics. The results and advantages of this approach have been demonstrated in wells in mature Mexican fields featuring significant reach and pressure limitations.
In recent years, CT equipped with real-time fiber-optic telemetry has been a method of choice to perform interventions in deviated or horizontal wells, as it provides a cost-efficient and flexible alternative to heavier wired CT. In the Mexican fields, this real-time telemetry capability is used to accurately place the guns thanks to downhole casing collar locater and gamma ray tools. The need for pumping fluids to enable detonation, often performed during typical CT perforating operations, is eliminated through the use of a downhole microprocessor-controlled firing head, which is directed by commands sent from surface through the optical fiber.
The result is a nearly instantaneous detonation downhole and positive confirmation provided in real time through an array of sensors in the bottomhole assembly (e.g., accelerometers, pressure, and temperature). The absence of working fluid eliminates any concern of hydraulically loading the well or the need for shut-in, thus significantly reducing the extent of deferred production. It also mitigates uncertainties linked to the influence of downhole conditions on the behavior of working fluids or the potential malfunctions of drop balls. This system is capable of multizone, selective detonation, therefore improving operational flexibility through reduced gun runs. It is also compatible with any other traditional CT service and can easily be combined with a bridge plug setting, a nitrogen lift, or a cleanout within the same run. The approach and its associated workflow enabled a significant reduction in intervention turnaround time by cutting as much as 75% of the time necessary to detonate the guns once the depth has been correlated, while providing fast and clear confirmation of downhole detonation.
This evolved approach not only addresses the conveyance limitations of highly deviated and horizontal wells, it also greatly improves the safety, reliability, and efficiency of underbalanced perforating interventions by leveraging the real-time downhole monitoring and control capabilities of CT with fiber optic telemetry.
Abu Roash-D is characterized as a carbonate reservoir in Abu Gharadig field, Western Desert of Egypt. It has a good lateral continuity, contains natural fractures with poor connectivity in addition to formation tightness. To further increase the production from the field, a full development plan for Abu Roash-D carbonate reservoir was initiated with drilling of horizontal wells. The main objectives of drilling such horizontal wells was to develop the tight unconventional reservoirs and increase production by dramatically increasing the contact area with the producing interval, maximizing drainage volume around a well and link the natural fractures network thus, achieving an economically production targets.
The effective placement of sufficient acid volume along the open-hole section of such horizontal wells provides significant challenges in acid diversion due to the high permeability streaks that requires a very effective diversion technique for optimal acid distribution a long the open hole lateral for a successful acid stimulation treatment.
A fiber optic enabled coiled tubing attempts to tackle some of these limitations. This new approach deploys downhole sensors with fiber optic telemetry inside the coiled tubing string provides a real time temperature, pressure and correlated depth measurments. The fiber optic telemetry allows distributed temperature surveys recording for obtaining temperature profiles across the entire wellbore. Monitoring the distributed temperature sensing (DTS) profiles accompined with downhole pressure data interpretation enables real time diagnostic of downhole events between the stimulation stages providing an important aid to further optimize and improve the performance of stimulation treatments.
This paper presents case histories of the first time implementation of horizontal wells in Abu Roash-D tight carbonate reservoir in Egypt's western desert in which fiber optic enabled coiled tubing was utilized to optimize stimulation treatment. The real time monitoring of downhole distributed temperature sensing profiles allowed the identification of both high permeability zones as well as tight zones across the entire openhole lateral. This enabled the operator to take pro-active decision on where to spot diverter or acid, select the best diversion technique and allow for treatment optimization.
Azeri-Chirag-Gunashli basin is a large complex of oil fields in the Azerbaijan sector of Caspian Sea. Hydrocarbon deposits in ACG are mostly located in Sandstone reservoir thus formation sand invasion into the well encountered throughout the world at this type of the formation, is common issues experienced in the field. A-09Z oil producer well finished with open hole screen completion had screen failure issue which resulted large amount of sand filling up the wellbore. The operator requested to clean the sand out of the well along horizontal section and isolate the existing production zone by setting the bridge plug to further perforate an interval above.
This paper describes the use of an integrated sand cleanout system to remove the formation sands out of this challenge well. The well was drilled to near horizontal with a large completion size and long tangential section around 60o. A hydraulically actuated, switchable circulation sub was used with a real time downhole measurement system. While running into the well, forward jets of the sub help break down debris. While pulling out of the well, the tool is switched to a low resistance, backward jetting mode, which sweeps debris more efficiently using higher flow rates. The real time downhole measurement with a robust conductor inside CT is used to verify the switchable circulation sub to be operated correctly. A sand monitor was used in the surface return line to continuously monitor the returned sand flux. The integrated cleanout system helps reduce the overall operation costs by making the job more efficient in terms of equipment usage and operation time.