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Results
High-Performance Water-Based System Proved an Environmentally-Friendly Alternative for Time-Sensitive Shales in Saudi Arabia
Hegazy, Mohamed (M-I SWACO, A Schlumberger Company) | Sharma, Sunil (M-I SWACO, A Schlumberger Company) | Fares, Khaled (M-I SWACO, A Schlumberger Company) | ElBatran, Ahmed (M-I SWACO, A Schlumberger Company)
Abstract The Khafji and Ahmadi shales in Saudi Arabia are highly dispersive, tectonically stressed formations and tend to result in wellbore instability after prolonged exposure to conventional water-based drilling fluid systems. These time-sensitive formations can cause sloughing shale, packing off, extreme over pull, back reaming, stuck pipe, and in some instances bit and stabilizer accretion, resulting in non-productive time (NPT) to operators. Some off-set wells experienced lost time of up to 30 days, and after failing to continue with conventional water-based drilling fluid, the operator had to plug back and use oil-based drilling fluid to finish the wells. Historically, a standard KCl/polymer/asphalt system was used to drill these shale sections, but due to related NPT and an extensive evaluation program planned for a candidate well, the need for a more robust fluid was identified. Oil- or synthetic-based drilling fluids were not desired due to logistical and environmental concerns. In this challenging well, the operator planned to cut five cores across a series of formations to complete the geological studies previously hindered due to shale-related wellbore problems. These demanding objectives and the notorious history of the field, required a novel solution that could control the formations while maintaining an excellent environmental and logistical footprint. This paper presents details of the successful application of a new high-performance water-based drilling fluid (HPWDF) system using a unique triple inhibition approach to stabilize troublesome zones. In this new system, a proprietary polyamine-based shale hydration suppressant, a unique low-molecular-weight encapsulator, and a co-polymeric nano-sized pore-sealant additive worked in synergy to achieve oil-based fluid performance. In the field application, the system exceeded the operator's expectations, with no fluid-related downtime and successful execution of five coring runs. After coring and logging, casing was run and cemented smoothly, even after 42 days of wellbore exposure. With similar formations drilled across the Middle East, this solution has the potential to be used as an environmentally-friendly alternative to oil-based fluids in the Middle East.
- Asia > Middle East > Saudi Arabia (0.72)
- Asia > Middle East > UAE > Abu Dhabi Emirate (0.29)
- Asia > Middle East > UAE > Abu Dhabi > Arabian Gulf > Rub' al Khali Basin > Abu Al Bukhoosh Field > Arab Formation (0.99)
- Asia > Middle East > Saudi Arabia > Arabian Gulf > Arabian Basin > Arabian Gulf Basin > Wasia Formation (0.99)
- Asia > Middle East > Oman > Central Oman > South Oman Salt Basin > Nahr Umr Formation (0.99)
- (12 more...)
Testing and Evaluation of Shale Stability for Zubair Shale Formation
Abbas, Ahmed K. (Iraqi Drilling Company, Missouri University of Science and Technology) | Flori, Ralph E. (Missouri University of Science and Technology) | AL-Anssari, Ahmed (Weatherford) | Alsaba, Mortadha (Australian College of Kuwait)
Abstract Zubair Formation consists of approximately 55% shale, which causes almost 70% of wellbore problems due to incompatibilities of drilling fluids and shale formations. The most common and effective solution to shale instability is through the design and selection of drilling fluids. Understanding the interaction between drilling fluids and shale has been a challenge due to the complexity of both physical and chemical variations in shale formations. This paper presents some of the important laboratory and well-site testing techniques that are often used by mud engineers for characterizing and remediating drilling fluids and shale interaction. Well-preserved shale samples were analyzed to describe the special characterization of the Zubair shale. Moreover, the traditional laboratory methods such as capillary suction time test, hot rolling dispersion test, bulk hardness test, and the linear swelling test were used to evaluate the stability of shale in the presence of test fluids. Our laboratory test results show that the Zubair shale is composed mainly of brittle mineral (quartz and calcite) with average content 51.46% and 43.54% of the clay mineral. In addition, the cation exchange capacity analysis and capillary suction time test indicated that Zubair shale has low to moderate reactivity with drilling fluids. This paper will present the preliminary process of analysis and understanding of shale structural failures due to shale/fluid interactions. Consequently, it can be used to control and minimize shale instability by improving the selection of chemical additives for clay inhibition.
- Asia > Middle East (1.00)
- North America > United States > Texas (0.28)
- North America > United States > California (0.28)
- South America > Argentina > Patagonia > Neuquén > Neuquen Basin > Vaca Muerta Shale Formation (0.99)
- Asia > Middle East > Iraq > Basra Governorate > Arabian Basin > Widyan Basin > Mesopotamian Basin > Zubair Field > Zubair Formation (0.98)
- Asia > Middle East > Iraq > Basra Governorate > Arabian Basin > Widyan Basin > Mesopotamian Basin > Zubair Field > Mishrif Formation (0.98)
Abstract The wellbore quality can be affected by a multitude of factors that include drilling operations practices, drilling fluids quality, and geomechanical quality. Low quality wellbores lead to many complications that will result in well completion delay of. One factor of success in drilling operations is minimizing enlargements and tight spots. A new assessment process was developed to understand and analyze the influence of drilling operational practices on the wellbore shape. The analysis helps to identify the root causes of wellbore enlargement and propose mitigation solutions. More than 20 wellbores have been analyzed. Those wellbores penetrate a carbonate sequence followed by a sandstone sequence. This is to characterize the variations in the wellbore shape, in terms of enlargements and tight spots, against a set of well-defined parameters affecting it. For these wellbores, the mechanical properties and the stresses were estimated to correlate the geomechanical aspects of penetrated formations to the behavior of the wellbore geometry. Cyclic lateral loading of the drillstring, mud-controlled swabbing, and unintentional deviation in some wellbores were also investigated. The assessment concluded that cyclic lateral loading, due to reaming and vibrations, is a key factor of influence in changing the wellbore shape. Also, the mud-controlled swabbing proved to have a significant role in hole enlargements specifically. This was found to be evident in wellbores that employ highly viscous mud with a 30 min. gel strength of more than 25 lb/ft. It was also found that using mud with low chloride concentration, below 30 g/L, contributed to the varying geometry of wellbores. Applying the recommendations generated by this work will help to refine the quality of future drilled wellbores and consequently, mitigate the risks of pack-offs, stuck-pipe incidents, sidetracking, low quality logs, and casing-casing annular pressure. Also, this work will present a new approach for real- time wellbore quality prediction and monitoring using advanced data analytics tools.
- Asia > Middle East > Saudi Arabia (0.46)
- North America > United States > Texas (0.28)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.34)
- Well Drilling > Wellbore Design > Wellbore integrity (1.00)
- Well Drilling > Drilling Operations (1.00)
- Information Technology > Data Science (0.54)
- Information Technology > Architecture > Real Time Systems (0.34)