Acid fracturing has been an integral part of reservoir development strategies for carbonate reservoirs as mechanical and chemical means of bypassing formation damage enhances productivity. Over the past few years, acid fracturing has significantly increased targeting more carbonate reservoirs. There is a need to fully address the heterogeneous petrophysical and geomechanical properties of target reservoirs, which adversely affects the stimulation efficiency and production if fluids are not properly designed. When injecting stimulation fluids to fracture the reservoir rock, the fluid is prone to traveling along the path of least resistance, and consequently less permeable zones and high stress reservoir rock receive treatments that could be further improved or enhanced. Accordingly, this drives the industry to continuously develop high performance chemical dynamic diverter systems. To ensure an effective and sufficient acid fracturing is achieved when treating long intervals of perforated clusters or openhole horizontal wells. Recent advancements in diversion technology utilize various forms of degradable particles, where they serve to provide a temporary bridge, which is either inside the existing fracture or the perforation entrance. This allows for intentionally forming a low permeability pack, allowing the pressure inside the fracture to increase and redirect the next stage of fluid to the zone having a higher degree of stress that has not yet been covered by the fracture. The objective is to increase the fracture complexity, particularly in vertical wells where there is big variation in geomechanical properties of the formation. To gain a deeper understanding of the performance of these diverters, a simulation study was conducted to analyze and compare the efficiency of particulate diverters used in two pilot wells. Fracture modelling and sensitivity analysis were also performed to understand the effect of diverters on the fracture geometry. To match the actual treatments, modelling validation and control were achieved through utilization of field data such as production logging, temperature surveys and pressure buildup tests. The study determined that the success of the particulate diverter employed for the fracturing application is heavily dependent and governed by the geomechanical properties of the treated zone and the ability of the diverter to overcome the stress difference in the stimulated interval. Optimization of the diverter design and degradation profile is still needed to improve and achieve the best stimulation efficiency.
This paper presents the first-time application of high pressure/high temperature (HP/HT) water swellable packers worldwide for multistage fracturing completions. This technology eliminates deployment risks associated with premature swelling in high temperature oil-based muds (OBM) and improves efficiency of fracturing operations in tight gas reservoirs. The overall deployment method of this technology is similar to traditional open-hole multistage fracturing technologies that are industry standard. The main difference being that the isolation packer used is an HP/HT water swell packer that uses water/brine as the swelling medium as opposed to hydrocarbon. The technology comprises of an innovative compound that is capable of holding high differential pressure at high reservoir temperatures and maintaining permanent isolation in a relatively compact element length. The elastomer compound completed an extended qualification process to ensure fulfilling deployment and fracturing completion requirements in a specific well candidate. The outcome was an overall successful deployment and stimulation operation of multi stage completion with HPHT water swell packer technology. Water swell packer provided the ability to deploy the lower completion in high temperature/OBM environment with a significant increase of swelling factor delay and its compact length reduces stiffness in the BHA to further decrease the deployment risk. In addition, this technology provided an optimization technique for open-hole multi-stage stimulation by circulating out the drilling mud and leaving completion brine in the wellbore and annular space. Through a complete diagnostic process, it was confirmed that the water swellable packers successfully isolated each stage of the stimulation treatment. Prior to the first worldwide installation of an innovative elastomer compound, unique testing was conducted in the laboratory and in field tests to qualify the compound technology with special focus on the acid stimulation treatments domain. The elastomer compound was made of special fillers to chemically retain water in the elastomer matrix and eliminate any reverse osmosis problem present in traditional water-swellable compounds.
This paper presents the first application of metal expandable frac packers for multistage acid fracturing (MSF) completions. This technology significantly reduces deployment risk commonly associated with openhole (OH) MSF completions with the ability to rotate while running in hole without any risk of premature expansion or compromising integrity of the sealing mechanism. Additionally, it improves efficiency of fracturing operations in tight gas reservoirs with the ability to expand to larger borehole diameters than is possible with current isolation packer technologies. The overall deployment method for this technology is similar to traditional openhole multistage fracturing completions that are industry standard. The main difference is that the isolation packer used is expanded by pressure to mechanically deform the metal sleeve to provide sealing against the open hole. The technology comprises an innovative material and design that can hold high differential pressure at high reservoir temperatures while maintaining permanent isolation in a relatively compact element length. The metal expandable frac packer completed an extended qualification process, including American Petroleum Institute (API) testing, to fulfil deployment and acid fracturing completion requirements. The outcome was an overall successful deployment and stimulation operation of multistage completion with the metal expandable frac packer. The metal expandable frac packer provided the ability to deploy the lower completion in difficult wellbore conditions with ability to rotate. The metal expandable frac packer is set with pressure; therefore, there is no waiting time to have full differential pressure capabilities for the fracturing operations. This technology provided a flexibility factor for packer placement as the metal expandable packer technology can hold its rated pressure at larger borehole diameters. Since the mechanism of the metal packer is expansion by inelastic deformation, the metal expandable sleeve conforms perfectly to the geometry of the borehole, providing a highly reliable seal for high pressure fracturing operations. Through a complete diagnostic process, it was confirmed that the metal expandable packers successfully isolated each stage of the stimulation treatment. Metal expandable frac packers unique testing was conducted in the laboratory and in field to qualify the technology with special focus on the chemical composition for the fluids encountered for the deployment, stimulation, and production environments including high concentration acid fracturing applications. The metal expandable sleeve technology utilizes a unique double-sleeve system for pressure compensation to enhance the sealing integrity of MSF stimulation operations and truly provide 10,000 psi under API 19OH V1.
Inflow control device (ICD) completions are becoming a crucial part for many green and brown field developments. However, a typical ICD completion requires a washpipe or inner string to provide fluid circulation, displacement and setting of openhole hydraulic-mechanical packers, which increases operational time, risks and costs. A typical installation process has to follow a series of operational steps to ensure successful deployment of ICD completions. Those necessary operational steps are traditionally achieved using washpipe or an inner string that is run inside the lower completion bottomhole assembly (BHA). This unique and advanced ICD completion design uses proven sliding-sleeve technology that will be run in the closed position to provide fluid circulation, displacement and setting of openhole hydraulic -mechanical packers, and then hydraulically activated to the open position to allow for reservoir-to-well communication. It also incorporates a mechanical-shifting mechanism for future reservoir management and control. The new and advanced ICD completion has undergone a rigorous testing program to ensure the design will deliver those operational requirements and perform appropriately under the worst well operational conditions that are expected during the field life. Following completion of the testing program, the advanced ICD completion was deployed flawlessly in a carbonate reservoir well in the Middle East, representing the first successful deployment globally. The system has functioned as expected with clear surface indication throughout the different operational steps and the final establishment of reservoir-to-well communication which was evidenced by the increase in the well head pressure (WHP). Furthermore, the individual ICD open or closed-sleeve status was verified through production logging (PLT) and coil tubing (CT) shifting operations. The paper describes a comprehensive qualification testing program for the advanced ICD completion design to best serve those well-installation requirements without the need of washpipe. Furthermore, it details the actual well deployment which resulted in improved overall well completion design and operational efficiency.
Multi-stage matrix acidizing is a common stimulation technique applied in low permeability carbonate reservoirs to increase hydrocarbon production. Frac balls are utilized to activate stimulation sleeves to achieve pin-point stimulation. Frac balls used during each stimulation stage also help in isolating the already stimulated lower zones. However, subsequent milling interventions are required after stimulation to remove conventional composite or steel frac balls. Utilization of dissolvable frac balls eliminate the need of milling interventions and allows an obstruction-free path to the produced fluids. An overview of acid-resistant dissolvable frac balls deployed in a multi-lateral offshore multi-stage stimulation (MSS) application in conjunction with acoustic sensors is presented in this paper. A tri-lateral offshore well was drilled and completed with stimulation sleeve completions to perform multi-stage acid stimulation. The lower completion consisting of open-hole swellable packers and stimulation sleeves was successfully deployed with a metal-to-metal seal expandable liner hanger. The stimulation sleeves were successfully shifted open by the dissolvable frac balls. An additional real-time confirmation of the stimulation sleeve opening event was recorded with an acoustic system for every acid stimulation stage. Acoustic sensors provide increased operational efficiency through real-time diagnostic of dissolvable frac balls as they reach their respective baffles. Prior to deployment, the dissolvable frac balls were tested in a laboratory at downhole conditions to ensure that self-dissolution requirements of the frac balls are fulfilled. The dissolvable frac balls were successfully deployed in the offshore tri-lateral well, achieving required zonal isolation and hydraulic pressure integrity during multi-stage acid stimulation. Acoustic sensors provided real-time detection of each stimulation sleeve shifting open once the dissolvable balls reached their respective baffles. After the successful acid stimulation treatments, the frac balls dissolved from downhole conditions alone, allowing the return of full well-bore access on the three laterals for production. The utilization of dissolvable frac balls eliminated the subsequent coiled tubing milling interventions required with conventional frac balls after the stimulation. Significant costs and rig time was saved with this technology optimizing the post-stimulation phase of this tri-lateral well while achieving complete stimulation objectives. The dissolvable frac balls have proven to be acid-resistant in nature, with a differential pressure rating of up to 8,000 psi and temperature rating of up to 300°F. The paper presents the successful application of an acid-resistant dissolvable frac ball deployed in a challenging offshore environment. The dissolvable frac ball technology proved to be successful under these challenging environments, saving significant time and intervention costs. Additionally, the application of an acoustic sensors is also discussed, which allowed efficient completion design and seamless execution.
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.