BUR en forage : Comprendre le taux d'accroissement et son impact sur la trajectoire du puits
Dans le monde du forage et de l'achèvement des puits, le terme "BUR" signifie **Taux d'accroissement**. Il se réfère au taux auquel l'inclinaison d'un puits augmente pendant le processus de forage. Comprendre le BUR est essentiel pour gérer la trajectoire du puits, optimiser les opérations de forage et assurer la stabilité du puits.
**Qu'est-ce que le Taux d'accroissement ?**
Imaginez un puits foré verticalement. Au fur et à mesure que le forage progresse, le puits peut commencer à dévier de son trajet vertical, s'inclinant progressivement dans une direction spécifique. Cette déviation est connue sous le nom d'inclinaison du puits, et le taux auquel cette inclinaison augmente est le Taux d'accroissement (BUR).
**Facteurs influençant le Taux d'accroissement :**
- **Paramètres de forage :** Le BUR est directement influencé par les paramètres de forage tels que le poids sur l'outil (WOB), la vitesse de rotation et le poids du fluide de forage. Un WOB et une vitesse de rotation plus élevés peuvent entraîner un BUR plus élevé, tandis qu'une augmentation du poids du fluide de forage peut contribuer à le réduire.
- **Propriétés de la formation :** Les formations géologiques traversées par le forage ont un impact significatif sur le BUR. Les formations avec des roches plus faibles et une pression de pore élevée ont tendance à présenter un BUR plus élevé.
- **Outils et techniques de forage :** Le type d'outils de forage utilisés, tels que les mèches et les moteurs de boue, ainsi que les techniques de forage employées, peuvent influencer le BUR.
- **Conception du puits :** La trajectoire du puits planifiée, y compris l'inclinaison et l'azimut cibles, joue un rôle crucial dans la détermination du BUR.
**Importance de la gestion du Taux d'accroissement :**
- **Stabilité du puits :** Un BUR incontrôlé peut entraîner une instabilité du puits, causant des problèmes tels que l'effondrement du puits, le blocage du tuyau et la perte de circulation.
- **Contrôle de la trajectoire :** Une gestion précise du BUR est essentielle pour atteindre la trajectoire du puits souhaitée, en veillant à ce que le puits atteigne sa zone cible efficacement.
- **Efficacité du forage :** Le contrôle du BUR contribue à optimiser les opérations de forage en minimisant le temps consacré à la correction des déviations et en évitant les complications.
- **Coûts de forage :** Un BUR incontrôlé peut entraîner des travaux de réparation coûteux et des retards, impactant les coûts globaux du forage.
**Gestion du Taux d'accroissement :**
- **Surveillance en temps réel :** L'utilisation d'outils de fond de trou tels que le MWD (Mesure pendant le forage) et le LWD (Enregistrement pendant le forage) permet une surveillance continue du BUR et de l'inclinaison du puits.
- **Ajustement des paramètres de forage :** Sur la base des données en temps réel, les paramètres de forage tels que le WOB, la vitesse de rotation et le poids du fluide de forage peuvent être ajustés pour contrôler le BUR et maintenir la trajectoire souhaitée.
- **Techniques de forage directionnel :** Des techniques telles que le "fouettage" ou la "marche" du puits peuvent être utilisées pour contrôler et manipuler le BUR pendant le forage.
**Conclusion :**
Le Taux d'accroissement (BUR) est un paramètre crucial dans les opérations de forage, impactant directement la stabilité du puits, le contrôle de la trajectoire, l'efficacité et les coûts. Comprendre les facteurs influençant le BUR et mettre en œuvre des stratégies de gestion efficaces sont essentiels pour des projets de forage réussis et rentables. En surveillant, contrôlant et optimisant attentivement le BUR, les équipes de forage peuvent s'assurer que les puits sont forés en toute sécurité, efficacement et avec la trajectoire souhaitée.
Test Your Knowledge
BUR Quiz: Build-Up Rate in Drilling
Instructions: Choose the best answer for each question.
1. What does BUR stand for in drilling?
a) Bit Uplift Rate b) Build-Up Rate c) Bottom Up Rate d) Borehole Uplift Rate
Answer
b) Build-Up Rate
2. Which of the following factors does NOT directly influence Build-Up Rate?
a) Mud weight b) Formation properties c) Ambient temperature d) Rotary speed
Answer
c) Ambient temperature
3. What is a potential consequence of uncontrolled Build-Up Rate?
a) Increased wellbore stability b) Reduced drilling costs c) Wellbore collapse d) Improved trajectory accuracy
Answer
c) Wellbore collapse
4. Which technology allows for real-time monitoring of Build-Up Rate?
a) Mud logging b) Wireline logging c) MWD (Measurement While Drilling) d) Seismic surveys
Answer
c) MWD (Measurement While Drilling)
5. Adjusting which drilling parameter can help control Build-Up Rate?
a) Mud density b) Drilling depth c) Rig horsepower d) Drilling fluid viscosity
Answer
a) Mud density
BUR Exercise:
Scenario:
A wellbore is being drilled with the following parameters:
- Weight on Bit (WOB): 40,000 lbs
- Rotary Speed: 100 RPM
- Mud Weight: 12.5 ppg
The wellbore is currently at an inclination of 30 degrees. The drilling engineer observes that the Build-Up Rate is 1 degree per 100 feet drilled.
Task:
- Calculate the expected inclination of the wellbore after drilling 500 feet.
- Analyze the potential consequences of this BUR for the wellbore stability and trajectory.
- Suggest two possible actions the drilling engineer can take to control the BUR and achieve the desired trajectory.
Exercice Correction
1. Expected Inclination:
- BUR = 1 degree per 100 feet
- Distance drilled = 500 feet
- Total inclination increase = (1 degree/100 feet) * 500 feet = 5 degrees
- Expected inclination after 500 feet = Initial inclination + Inclination increase = 30 degrees + 5 degrees = 35 degrees
2. Potential Consequences:
- Wellbore Stability: The relatively high BUR (1 degree per 100 feet) suggests the formation may be relatively weak or have high pore pressure. This could lead to potential issues like wellbore collapse, stuck pipe, and loss of circulation if not managed effectively.
- Trajectory: The BUR exceeding the planned trajectory can result in the well deviating from its target zone, potentially impacting reservoir access and production.
3. Actions to Control BUR:
- Reduce WOB: Decreasing the weight on the bit can reduce the stress on the formation, potentially lowering the BUR.
- Increase Mud Weight: Increasing mud weight can provide better wellbore support and counter the formation pressure, helping to minimize the BUR.
Books
- "Drilling Engineering" by Bourgoyne, Millheim, Chenevert, and Economides: This comprehensive textbook covers various drilling aspects, including wellbore trajectory control and BUR.
- "Directional Drilling Manual" by John C. Haas: This manual focuses on directional drilling practices and includes sections on BUR analysis and management.
- "Petroleum Engineering Handbook" by Society of Petroleum Engineers: This handbook provides an extensive overview of petroleum engineering, with sections on drilling and wellbore stability that may include BUR information.
Articles
- "Build-Up Rate Control in Directional Drilling" by SPE: Search the Society of Petroleum Engineers (SPE) website for articles related to BUR, particularly those focusing on control methods and best practices.
- "Factors Influencing Build-Up Rate in Horizontal Wells" by Journal of Petroleum Technology: Look for articles in reputable drilling and petroleum journals that explore the relationship between BUR and drilling parameters, formation properties, and wellbore design.
Online Resources
- SPE website (www.spe.org): The SPE website offers a vast library of technical papers, articles, and presentations on various drilling topics.
- ONEPetro (www.onepetro.org): This platform houses a wealth of technical content from multiple industry organizations, including SPE publications.
- DrillingInfo (www.drillinginfo.com): DrillingInfo offers data and analytics for the oil and gas industry. They may have resources specifically related to BUR and wellbore stability.
Search Tips
- Use specific keywords: When searching for BUR information, try terms like "build-up rate drilling," "build-up rate control," "directional drilling build-up rate," or "wellbore stability build-up rate."
- Combine with other terms: Use keywords related to your specific area of interest, such as "build-up rate shale formations" or "build-up rate horizontal wells."
- Filter your results: Use advanced search operators in Google, like "site:" to specify a particular website (e.g., site:spe.org build-up rate).
- Explore related topics: Look for content related to wellbore stability, directional drilling, drilling parameters, and formation properties.
Techniques
Chapter 1: Techniques for Managing Build-Up Rate (BUR)
This chapter explores the various techniques employed to manage and control the Build-Up Rate (BUR) during drilling operations.
1.1. Real-Time Monitoring:
- MWD (Measurement While Drilling): This technology transmits data from sensors located in the drill bit to the surface in real-time, providing continuous monitoring of BUR, wellbore inclination, and other crucial parameters.
- LWD (Logging While Drilling): Similar to MWD, LWD utilizes sensors in the drill bit to gather data about the formation being drilled, including formation properties that can influence BUR.
- Geosteering: This technique integrates real-time data from MWD and LWD with geological models to guide the wellbore trajectory and control BUR effectively.
1.2. Adjusting Drilling Parameters:
- Weight on Bit (WOB): Reducing WOB can significantly decrease BUR, especially in formations with low rock strength.
- Rotary Speed: Lowering rotary speed can also minimize BUR, reducing the rate of bit penetration and minimizing the tendency for the wellbore to deviate.
- Mud Weight: Increasing mud weight provides better borehole stability and can help reduce BUR in formations with high pore pressure.
- Bit Selection: Choosing the appropriate bit type and size for the formation being drilled can optimize the drilling process and minimize BUR.
1.3. Directional Drilling Techniques:
- Whipping: This technique involves rapidly alternating the direction of the bit, creating a "whipped" trajectory that helps control BUR and maintain the desired wellbore inclination.
- Walking: This technique uses controlled lateral movements of the bit to steer the wellbore along a specific path, effectively managing BUR and achieving the desired trajectory.
- Sidetracking: In cases where the wellbore deviates significantly from the planned trajectory, sidetracking may be required to re-enter the desired path.
1.4. Wellbore Design:
- Wellbore Trajectory Planning: Designing the wellbore trajectory with an optimized inclination and azimuth is crucial for minimizing BUR and achieving the desired target zone.
- Anticipated Formation Properties: Incorporating knowledge of the expected formation properties during wellbore design can help anticipate BUR and plan appropriate drilling strategies.
Conclusion:
By effectively implementing these techniques, drilling teams can minimize the impact of BUR on wellbore stability, trajectory control, and overall drilling efficiency.
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