For the last 30 years, wells in the field have been suffering from medium to high corrosion rates in both near surface and downhole components. Remedial measures had been implemented in order to restore Well Integrity with different techniques. Corrective actions aside, a strong preventive approach is needed to better understand the root causes of such corrosion rates and scenarios where the integrity of specific wells has been seriously compromised due to corrosion problems.Taking a step further and considering the big implications of new projects such as Artificial Islands project, where the company will be drilling & completing over 300 Extended Reach Drilling (ERD) wells, Well Integrity input as a discipline becomes critical in order to ensure previous problems will not be repeated and all lessons learned throughout the years will be wisely taken into consideration when designing a new well to remain integral during its whole expected life.Understanding of the current corrosion mechanisms in the field was the key to find not only solutions, but also, to create an approach aimed to improve the future completion for Island wells in terms of design, materials and many other factors.An extensive multidisciplinary approach was carried out in order to successfully complete a full study in one of the pilot wells completed with Inflow Control Devices (ICDs), which will be analyzed in detail in this paper, covering the following areas:i. Well design and configuration ii. Well monitoring and performance review iii. Well diagnosis and failure investigation iv. Post-Failure modelling and well prediction v. Preventive/Corrective actions for future wells. Corrosion management and prevention of scale deposits were the two main challenges encountered during this project, which was launched and completed with the main objective of evaluate and optimize the ICD completion design in one Maximum Reservoir Contact (MRC) pilot well in the field, the findings and lessons learnt were used to upgrade the current well design and improve the development plan for the field.
The recent industry development of drilling ERD wells with horizontal laterals in the reservoir of 10,000 ft. or more has led to a greater use of passive flow control devices and swell packers to achieve the desired inflow or outflow profiles. Another desire is to perform stimulation treatments of the lateral especially in tight carbonate formations. However, such treatments can create high velocities through the Inflow Control Devices (ICDs) that inevitably leads to high turbulence and wall shear stress in the ICD which can cause severe erosion and corrosion of commonly used materials. There appears to be little experience and associated knowledge on corrosion mitigation to ensure ICD integrity after well stimulation. This paper will attempt to address such concerns through: Discussing and analysing ICD design considerations to avoid high corrosion areas and selection of high alloy materials to resist corrosion. Selection of appropriate acid system and method to prevent corrosion. Laboratory testing of acid formulations under high wall shear conditions as predicted from Computational Fluid Dynamics (CFD) of the ICD design at reservoir conditions. Laboratory measurements of the performance of corrosion protection additives in acid formulations under wall shear conditions. Other possible mitigation efforts to reduce the need for stimulation treatments. Each of these factors presents limitations which either restricts the use of aggressive acid systems or requires alternative acid systems that can lead to increased treatment cost and/or sub-optimal stimulation of the reservoir through the ICDs. This paper discusses one producing company's effort to systematically improve the overall performance of stimulation through ICDs while maintaining the integrity of the lower completion liner.
In this paper, a new carbonate stimulation methodology and its impact to the planning of very long, open hole completions will be presented. While the key objective of stimulation is to connect the well to the reservoir, completion equipment design and related well performance have become more important factors. Traditional methods of stimulation modeling and fluid placement are no longer sufficient for these types of wells. This paper introduces how completion design becomes more complex for more aggressive stimulations. For example, completions with pre-drilled or slotted liners for stimulation with coil tubing acid wash are less sophisticated than ball drop liners for high-volume acidizing or fracturing. In long horizontal completions, computer modeling of stimulation needs to address the flow conditions caused by liners, swell packers and inflow control devices (ICDs). Recent well planning for a long horizontal pilot well (Pilot Well 5) has included the use of new carbonate matrix stimulation software to design a fit-for-purpose completion liner that will accommodate bullhead treatment of a long completion interval. Various completion designs were considered based on objectives from reservoir engineering and geology. Being part of a pilot well program, the strategy is to test fit-for-purpose liners that would balance completion cost with long term productivity and recovery. The well design required more than 100 runs of the new carbonate matrix acidization software to finalize a liner design that employs over 200 holes distributed along the length of the lateral. The final design was developed to accommodate uncertainties in the reservoir properties and allow for safe and reliable rig operations. The resulting design could serve as a lower-cost alternative to ball drop stimulation liners for long openhole completions.
This paper describes the design and installation of the lower completion and acid stimulation of two 20,000-ft-measureddepth extended-reach (ER) wells in a major oil field offshore Abu Dhabi. The wells each had 10,000-ft horizontal completion intervals in a carbonate reservoir. One well was a producer, and the second well was a parallel water injector. The wells were each completed with an engineered, pre-perforated liner run with ten swell packers. The acidizing was performed using a specially-designed 2.375-inch coiled tubing string run with a spiral jet nozzle bottomhole assembly.About 180,000 holes were pre-drilled in each 6.625-inch completion liner using a special hole pattern based on computational fluid dynamics and finite element design. The liners were run to total depth; these are believed to be the longest high-hole density pre-drilled liners ever run. Pre-stimulation logs were run to determine the inflow and outflow and pressure profiles. Blank pipe placed above and below the swell packers helped determine the contributions from each reservoir unit. These data were used to optimize the design of the acid stimulation treatments. The acid treatments were placed by varying the pulling speed of and the pump rate into the coiled tubing. Simultaneous annular water injection was used to help divert acid away from the heel portion of the injector well.These wells serve as pilot wells to help confirm the feasibility of developing the field using maximum-reservoir-contact (MRC) wells rather than the current practice of using much shorter (e.g., 3,000 ft) openhole completions. The use of MRC wells is expected to significantly reduce development costs over the life of the field.
To develop a giant carbonate oil field offshore Abu Dhabi, more than 300 wells are planned to be drilled from 4–6 artificial islands. Current plans are for these wells to be linear maximum reservoir contact (MRC) wells having horizontal completion intervals of 10,000 ft. A significant number of the wells will be extended-reach (ER) wells having measured depths exceeding 20,000 ft, and a number of the wells will have measured depths greater than 30,000 ft. One of the main challenges for these linear MRC wells is achieving adequate acid stimulation over the 10,000-ft completion interval. This paper discusses completion and stimulation options for these wells. Several of these options are illustrated by two 10,000-ft-completion-interval linear MRC pilot wells that have been drilled, completed, and stimulated from existing wellhead platform towers. These pilot wells were completed with preperforated liners equipped with ten swell packers. The stimulation treatment was performed using coiled tubing and a radial jetting tool. The completion design for a third linear MRC pilot well is also discussed. This well has been designed with a solid liner containing more than 15 swell packers and more than 35 inflow control devices (ICDs). The stimulation treatment will be performed through the ICDs. The paper also discusses a new concept for completing these types of wells using ICDs and acidizing check valves.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.