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Objectives/Scope A new vision with new techniques of wells’ upper and lower completions have been applied successfully throughout a giant offshore multi-reservoir oilfield. Wells with long to very-long laterals have been completed successfully following a systematic strategy based applications and showed tremendous success. This paper will present the various techniques used completing wells in different reservoirs considering well-integrity and HSE regulations in order to achieve the maximum wells’ deliverability’s at their lowest costs throughout the well life. Many challenges were faced and overcame in order to reach the optimum completion that suits each well. A complete journey from reservoir simulation to well and network models, well performance to reservoir management studies, from geological models and interpretation to geo-science and seismic inputs, in addition to actual production data, all helped to achieve the over-all target. From the phase of design to the phase of implementation and beyond to the production phase, each piece of information yielded a certain potential that led to a certain completion design based on available data and expectations. Methods, Procedures, Process This paper will discuss the new innovative upper and lower completion designs’ strategies along with the execution and performance from production engineering perspective in order to reach the maximum productivity for the life cycle from these long horizontal wells at the lowest possible cost. The extended lateral length in these wells warrants innovative designs in upper and lower completions, as the traditional completion designs no longer suite to address the challenges in these wells. The key well design and planning process involves designing the upper completion including suitable tubing size with the most effective and durable gas-lift system, and lower completion liner designs for different wells’ cases. Efficient initial strategies to start-up wells including some protocols with well-performance monitoring and reservoir surveillance. The paper will also address and discuss the challenges in long horizontal wells such as accessibility, production/injection conformance, and effective stimulations of these laterals. Results, Observations, Conclusions This paper will discuss and show many examples of the completed wells with different types of completions and a comparison of their performances after initial startup and during the back-flow period in addition to the extended performance during normal flowing conditions. Some LEL wells were logged and stimulated showing excellent results; these results will be shared in the paper. It is concluded that the LEL completion proved itself to be the future for lower completion to be widely used in the field. Novel/Additive Information The novelty of such new applications were that they were designed in-house and applied on considerable number of long lateral wells showing excellent results that is changing the completion future strategy in the field and may be in the region or even worldwide.
Objectives/Scope A new vision with new techniques of wells’ upper and lower completions have been applied successfully throughout a giant offshore multi-reservoir oilfield. Wells with long to very-long laterals have been completed successfully following a systematic strategy based applications and showed tremendous success. This paper will present the various techniques used completing wells in different reservoirs considering well-integrity and HSE regulations in order to achieve the maximum wells’ deliverability’s at their lowest costs throughout the well life. Many challenges were faced and overcame in order to reach the optimum completion that suits each well. A complete journey from reservoir simulation to well and network models, well performance to reservoir management studies, from geological models and interpretation to geo-science and seismic inputs, in addition to actual production data, all helped to achieve the over-all target. From the phase of design to the phase of implementation and beyond to the production phase, each piece of information yielded a certain potential that led to a certain completion design based on available data and expectations. Methods, Procedures, Process This paper will discuss the new innovative upper and lower completion designs’ strategies along with the execution and performance from production engineering perspective in order to reach the maximum productivity for the life cycle from these long horizontal wells at the lowest possible cost. The extended lateral length in these wells warrants innovative designs in upper and lower completions, as the traditional completion designs no longer suite to address the challenges in these wells. The key well design and planning process involves designing the upper completion including suitable tubing size with the most effective and durable gas-lift system, and lower completion liner designs for different wells’ cases. Efficient initial strategies to start-up wells including some protocols with well-performance monitoring and reservoir surveillance. The paper will also address and discuss the challenges in long horizontal wells such as accessibility, production/injection conformance, and effective stimulations of these laterals. Results, Observations, Conclusions This paper will discuss and show many examples of the completed wells with different types of completions and a comparison of their performances after initial startup and during the back-flow period in addition to the extended performance during normal flowing conditions. Some LEL wells were logged and stimulated showing excellent results; these results will be shared in the paper. It is concluded that the LEL completion proved itself to be the future for lower completion to be widely used in the field. Novel/Additive Information The novelty of such new applications were that they were designed in-house and applied on considerable number of long lateral wells showing excellent results that is changing the completion future strategy in the field and may be in the region or even worldwide.
ADNOC is progressing with large-scale rig-less high-rate matrix stimulation by deployment of advanced lower completions. A key contribution to future production growth is expected to come from these "Smart Liners" that rely on the principles of the limited-entry technique. The concept is based on a number of small, pre-drilled and unevenly spaced holes which enable an even distribution of acid along the entire reservoir drain to be stimulated. The smart liner incorporates swellable packers to avoid annular flow of acid to preferential zones and to isolate segments with heterogeneities. In this work, we focus on aspects related to planning, design and execution of high-rate matrix-acid stimulation of wells. We demonstrate that short wells need a different design approach compared to extended-reach wells and we provide guidelines on how to achieve the highest achievable pump rate and desired acid volume subject to reservoir, well and equipment constraints. The carbonate reservoirs typically exhibit considerable variation in permeability along the well, hence techniques for production profiling, such as inline tracers, are valuable for assessing the actual stimulation effectiveness. Wormhole penetration for a particular acid system will vary depending on the rock petrophysical properties and the reservoir properties; therefore, a systematic data analytics project is on-going.
Unit R is a tight carbonate reservoir onshore Abu Dhabi currently undergoing redevelopment with the aim to substantially improve the ultimate recovery factor. Better pressure support is required to increase the production. To this end, two water injectors were drilled in tight areas where wells suffer from low injectivity index and high well head injection pressure (WHIP). Reaching the expected injection rates therefore required very aggressive matrix-acid stimulation techniques. Acid wash is a common stimulation practice for medium-high permeability wells in ADNOC when the purpose is merely to remove drilling damage without creating large negative skins. For low permeability reservoirs such as Unit R, more aggressive stimulation techniques are needed to deliver the expected production and injection target rates. We tested two such methods; Well A1 was treated using Abrasive Jetting (JA), which is conveyed by coiled tubing whereas in Well A2, we deployed a Smart Liner (SL) where acid can be bullheaded at high rate from surface. In Well A1, the Abrasive Jet CTU in Open Hole doubled the injectivity index. However, the Injection Logging Test (ILT) revealed an uneven injection profile along the horizontal section (more injection in the better properties zone). In well A2, Smart Liner bull-head acid stimulation was able to triple the injectivity index. The ILT shown an even injection profile across the horizontal section, actually slightly more in areas with poor rock properties due to a large number of holes in those intervals. The cost of the Abrasive Jet is 40% less than the Smart Liner stimulation but the latter has more medium/long term advantages: Even injection along horizontal section (improving sweep efficiency) Ensure 100% accessibility to the well (avoiding formation collapse issue) Stimulation from surface, no need CTU (saving cost), useful for potential future re-stimulations. After only 10 months of injection the reservoir pressure has increased 50-100 psi in surrounding nearby oil producers, resulting in 20% more oil while honoring all operational guidelines. It is quite exceptional to be able to assess with real data the effectiveness of two different stimulation techniques. The two pilot wells have same horizontal length, almost same rock properties, and are drilled parallel to each other. Both Smart Liner and abrasive jetting substantially improve water injectivity but the more uniform flow profile observed in the Smart Liner is a distinct advantage when selecting an appropriate completion-stimulation design for future water injectors.
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