Diaz, Nerwing (Baker Hughes, a GE company) | Paila, Phalgun (Baker Hughes, a GE company) | Kirby, Cliff (Baker Hughes, a GE company) | Akl, Bassam (Baker Hughes, a GE company) | Mahmoud, Dalia (Baker Hughes, a GE company) | Al Kindi, Rashid Khudaim (ADNOC offshore) | Kasem, Youssef (ADNOC offshore) | Benygzer, Mhammed (ADNOC offshore) | Haddad, Mohamed (ADNOC offshore) | Leon, Vicente (Drilltech Services)
Directional drilling from artificial islands has become a common offshore practice in the United Arab Emirates, looking to minimize footprint while optimizing cost to reach maximum number of targets from a single location. This drilling practice brings some challenges such as torque and drag limitations, which is vital in order to safely reach wells total depth in well profiles with a high departure. The purpose of this paper is to discuss in detail the successful implementation of torque reduction techniques, focused on case histories from an artificial offshore island in the United Arab Emirates.
During the planning phase, Drilling Engineers estimate expected torque and drag for the different sections based on modeling and historical data, this process is key to assess the limitations and initiate the process of evaluating the different torque and drag reduction techniques to be implemented based on the application. The case histories presented in this paper show the successful implementation of proven torque and drag management techniques, such as; well profile optimization, torque reduction subs, deployment of lubricated mud, use of real-time directional data to minimize hole tortuosity, and deployment of Rotary Steerable Systems from top to bottom for improved hole quality.
There are different factors considered in the planning phase that make torque and drag management crucial, but drill pipes torque limitation was the main challenge to overcome in order to reach planned total depth in the case histories discussed in this paper. Wells trajectory and BHA optimization played an important role during the execution phase, as well as the deployment of lubricated mud and torque reduction subs which in conjunction provided an overall surface torque reduction of up to 28%.
The implementation of different torque and drag reduction methods are illustrated with the modeling results and actual drilling data collected during the drilling of these wells. Information and data discussed in this paper can serve as documentation to aid in the planning phase for wells with similar challenges.
Haddad, Mohamed (ADNOC Offshore) | Rashed Al-Aleeli, Ahmed (ADNOC Offshore) | Toki, Takahiro (ADNOC Offshore) | Pratap Narayan Singh, Rudra (ADNOC Offshore) | Gumarov, Salamat (Schlumberger) | Benelkadi, Said (Schlumberger) | Bianco, Eduardo (Schlumberger) | Mitchel, Craig (Schlumberger) | Burton, Phil (Schlumberger)
Injection of drilling waste into subsurface formations proves to be an environmentally-friendly and cost-effective waste management method that complies with zero discharge requirements. It has now become the technology of choice in offshore Abu Dhabi.
The aim of cuttings reinjection (CRI) is to mitigate risks associated with subsurface waste injection and reduce cuttings processing time and cost. In order to meet these goals, a cuttings reinjection subsurface assurance methodology was developed to improve cuttings processing and continuously monitor drilling waste injection operations.
Preparing for CRI operations required extensive drilling cuttings slurry testing to minimize processing time and develop optimum particle size distribution to reduce cost and increase the injected waste volume. The improvements were accompanied by downhole pressure and temperature monitoring of the injection well, thus facilitating analysis of injection pressures. Fracture containment was verified through a combination of pressure decline analysis, periodic injectivity test, temperature survey, and periodic modelling for fracture waste domain mapping. A backup injection well was used also as an observation well to monitor the pressure signitures in the injection formation.
More than 1 million barrels of drill cuttings and associated drilling waste have been safely and successfully disposed of into a single injection zone of CRI well over three years of operations.
The cuttings reinjection subsurface assurance method optimizes grinded cuttings particle size distribution, detects and identifies potential risks to provide mitigation options to prolong the life of the injector.
The proactive subsurface injection monitoring-assurance program was built into the fit for purpose CRI injection procedure to continually avoid injecting any rejected hard material, improve and update the process as per subsurface injection pressure responses, thus reducing processing time and cost, mitigating injection risks, and extending the injection well life.
This paper presents the unique and technically challenging cuttings slurry properties design and pressure interpretation experience learned in this project; the enhancement of cuttings processing helped increase injection volumes and an in-depth interpretation of fracture behavior which behaved like a risk-prevention tool with mitigation options. Significant enhancement was developed in slurry treatment procedures to avoid injectivity loss and maximize the disposal capacity.
High torque, friction factors, and pick up weights were major challenges encountered by a major operator in Abu Dhabi while planning to drill challenging extended reach development (ERD) wells with complex 3D profiles. Well torque and drag simulations showed that planned depths were not reachable with water-based muds. This paper describes the implementation of a mechanical lubricant, which resulted in significant decrease of the friction factors and turned an ERD well from not drillable to drillable with water-based mud.
After analyzing several possibilities, the solutions were narrowed down to two: use either a new generation mechanical lubricant or a reservoir non-aqueous fluid (NAF). The complexity was amplified by the necessity to re-design a filter-cake breaker for NAF, were this option to be selected, due to the type of completion. This second option would also create a substantial cost increase for the operator for products and rig time; therefore, the decision was made to introduce a mechanical lubricant.
A comprehensive study and lab tests were conducted to ensure compatibility and stability of the lubricant with a planned mud type at downhole conditions. The results of this study were promising enough for the operator to introduce this lubricant, aiming a substantial reduction in torque and drag to enable drilling of the longest horizontal section in the history of the project.
Before addition of the mechanical lubricant, drilling continued with a conventional type of lubricant, noticing an increasing tendency of torque and drag tracking the predicted trends. At a certain stage, drillstring buckling was observed and drillpipe started to reach their limits. To mitigate these impediments, the mechanical lubricant was introduced into the drilling fluid.
After reaching the optimum concentration, the mechanical lubricant eliminated buckling and provided significant reduction in torque, pick-up, and slack-off friction factors, respectively by 27%, 52%, and 42%. These parameter improvements facilitated continued drilling the well to final depth without reaching the drillpipe limits. Additionally, the well and bottomhole assembly (BHA) designs allowed for significant margins in case of a stuck pipe event, and based on the new friction factors, the well could be extended by 3,000 ft without reaching the drillpipe limits.
The impact of this exercise in future ERD wells is considerable. It will simplify well and completion designs, improve logistics by reducing the amount of chemical movements, facilitate drilling fluids selection, and optimize the well cost.
The paper covers the gaps related to drilling complex ERD wells with water-based drilling fluids. It provides detailed methods and procedures covering the suitable application of the mechanical lubricant and the extensive laboratory tests done during the planning stage, as well as the field application and results. The proposed solution can be used during the well planning process in any other area of the world.
Xi, Guifen (ADMA-OPCO) | Singh, Rudra (ADMA-OPCO) | Haddad, Mohamed (ADMA-OPCO) | Lecoq, Thierry Francis (ADMA-OPCO) | Al Badi, Bader Saif (ADMA-OPCO) | Zahaf, Kamel (ADMA-OPCO) | AL-Kindi, Rashid Khudaim (ADMA-OPCO) | AL-Wahedi, Khalid Ahmed (ADMA-OPCO) | Leblanc, John (ADMA-OPCO) | Singh, Hemant (Baker Hughes) | Perumalla, Satya (Baker Hughes) | Salter, Tim (Baker Hughes) | Imtiaz, Saad (Baker Hughes) | Kirby, Cliff (Baker Hughes) | Paila, Phalgun (Baker Hughes)
ADMA-OPCO has undertaken a prestigious campaign to drill a large number of wells from artificial island in ABC field, most of these wells are extended reach drilling (ERD) wells with step-out up to around 18,000 ft. Operational efficiency/costs for drilling ERD wells is highly dependent on the wellbore stability, especially while drilling through the problematic Nahr Umr shale at different deviations and azimuths. Nahr Umr shale has a known history of causing wellbore instability in UAE and the surrounding countries and therefore a geomechanical study was initiated to understand the geomechanical setting in ABC field as well as fluid-rock interaction between drilling fluid and Nahr Umr shale formation. The main objectives of this geomechanical study were to optimize well design and drilling fluids in order to drill through Nahr Umr shale interval efficiently, additionally estimation of sustainable pressure variation that major faults can take without being reactivated was also performed.
An integrated geomechanical study including a 3D geomechanical modeling was carried out, in order to ensure drilling through Nahr Umr shale formation efficiently. This study covered formation petrophysical characterization, chemical tests on cuttings from Nahr Umr shale, chemo-poroelastic modeling, weak bedding analysis and also faults reactivation analysis.
Based on the study mentioned above, both customized drilling fluids program and suitable mud weights were optimized to stabilize Nahr Umr shale, and mitigate different types of wellbore instability issues. In addition to mud fluid optimization, the sustainable pore pressure variation was also estimated for several major faults.
A successful drilling campaign is in progress; so far many deviated wells have been completed without any noticeable troubles while drilling through Nahr Umr shale. This geomechanical model is helping to implement an effective drilling program for a smooth well placement. A learning curve has been building up continuously for handling more complex well trajectories successfully in the future. From this study, it was realized that, not only fluid-rock interaction and geomechanics related factors need to be taken into consideration for stabilizing a wellbore, but also special attention is needed for the existing micro-fractures within the formation, where increase in mud weight may make hole condition worse. A balanced approach has been adopted including drilling fluid optimization in order to avoid possible multiple failure mechanisms.
Mehtar, Mohammed (Abu Dhabi Marine Operating Company) | Haddad, Mohamed (Abu Dhabi Marine Operating Company) | Toki, Takahiro (Abu Dhabi Marine Operating Company) | Gumarov, Salamat (M-I SWACO, a Schlumberger Company) | Benelkadi, Said (M-I SWACO, a Schlumberger Company) | Shokanov, Talgat (M-I SWACO, a Schlumberger Company) | Vizzini, Carla (M-I SWACO, a Schlumberger Company) | Mitchell, Craig (M-I SWACO, a Schlumberger Company) | Khudorozhkov, Pavel (M-I SWACO, a Schlumberger Company)
This paper examines the challenges, solutions and milestones of the hydraulic fracturing based cuttings reinjection (CRI) process implemented on two artificial islands offshore Abu Dhabi.
During the development of an offshore field from two artificial islands, disposing of vast amounts of drilling waste and cuttings, generated from almost 100 wells, presented a major challenge. The conventional skip-and-ship for onshore treatment and disposal was technically, logistically, and economically unviable and posed possible future environmental liability. After careful assessment, total containment of drilling waste on the islands through multiple hydraulic fractures in suitable formations, for permanent in-situ waste confinement, was concluded by the operator as environmentally and economically the only sustainable process.
Two CRI wells were planned on each island to accommodate an estimated 8 million barrels of drilling waste slurry expected to be generated at the islands. While CRI is a proven technology wherein cuttings are slurrified and injected into sub-surface formations, fracture injections have high risks too. Many failures are known in the industry, including well and formation plugging and waste breaches to sea-bed and near-by wells, with far-reaching consequences and liability to operators.
Considering the complexity of the multiple-hydraulic fracturing process that requires careful planning, execution, monitoring, and analysis, a comprehensive geomechanical study was performed to identify and characterize all potential injection formations to achieve successful long-term injection. This was followed by front-end engineering design (FEED), fracture simulations, CRI well design, surface facilities design, slurry simulations, and followed by careful execution.
Two CRI wells were drilled on each island. Specifically designed injectivity tests were performed on each well before commencing injection, followed by regular injectivity tests to continuously analyze fracture behavior. A carefully designed slurrification and injection process, incorporating detailed QA-QC at all process stages, was implemented that helped to avoid solids settling, fracture or perforation plugging, uncontrolled fracture propagation, or well integrity issues. About 500,000 barrels has been successfully injected to-date in two CRI wells with injection pressures as per FEED estimates.
The paper details also the proactive sub-surface injection monitoring-assurance program built into the CRI injection procedure to continually modify the process as per sub-surface pressure responses, thus proactively mitigating injection risks.
Periodical injectivity tests, model alignment studies, temperature logs, and fracture pressure analysis facilitated regular recalibration of the geomechanical model to define fracture-domain sizes, monitor fracture height growth, and estimate residual formation domain capacity as injection progressed.
The multiple-hydraulic fracture-based CRI process implemented first time in Abu Dhabi incorporates many unique features which can be applied in similar projects elsewhere. This paper also describes the downhole gauges for accurate pressure-temperature monitoring at perforations, a detailed slurry design, the particle-size distribution for slurry quality analysis and quality control, the sub-surface monitoring-assurance program and regular tests and recalibration studies.