Year-end Sale % OFF 
Abstract
Waterflooding is a common recovery method used to maintain reservoir pressure and improve reservoir oil sweep efficiency. However, injecting cold water into a reservoir alters the state of in-situ formation stress and can result in the formation fracturing. In other words, it can cause the initiation and growth of thermally induced fractures (TIFs), even when the original fracture propagation pressure is not exceeded. TIFs can cause non-uniform distribution of the fluid flow in wellbores, a reduction in sweep efficiency, and early water breakthrough in nearby production wells. Modelling and history matching workflows that consider the dynamic nature of the TIF problem are critical. These workflows improve and validate reservoir and geomechanical models, identify and confirm observed TIF onset and propagation periods, and provide a history-matched sector model with the rock mechanical and thermal properties and stress gradients that can be used with confidence for subsequent studies. Modelling and the underlining assumptions of fluid flow in the TIF and reservoir matrix, as well as geomechanical changes due to cooling of the reservoir during injection, are detailed below. A 3D reservoir simulator coupled with 2D finite element TIF and geomechanical models were used to manually history match an injector (NI6) in the N Field sector reservoir model in which a TIF was observed. In this study, history matching workflows were developed to consider the dynamic nature of TIF development during waterflooding. The reservoir and geomechanical models were improved and validated via the observed TIF onset and propagation periods. The history-matched models produced can be used with confidence in subsequent studies. The practical workflows and guidelines developed here can be used in waterflooding operations during the modelling, design, and planning stages. The novelty of this study is the coupling approach of different complex processes done in order to capture dynamic changes during waterflooding operations. A similar history matching study could not be found in the literature.
Highlights
It is well established in the oil industry that a large proportion of water injection wells are fractured at some time in their extended life [1,2]
This shows the significant impact of a temperature difference between the formation and injected fluid on stress reduction, henceprocesses on thermally induced fractures (TIFs) initiation and/or propagation propagation resulted fromand thermal is referred as Thermally
A detailed wellbore model was built in PROSPERTM i.e., well performance and design software developed by Petroleum Experts based on the well’s completion schematic, a survey, bottom hole pressure (BHP) measurements during an injection test, etc
Summary
It is well established in the oil industry that a large proportion of water injection wells are fractured at some time in their extended life [1,2] This includes injection wells initially injecting at a bottom hole pressure (BHP) lower than the original minimum horizontal stress (σhmin ) [3]. Whenmay the stress (σhmin minimum horizontal stress (σhmin) belowwell the due BHPto due temperature changes, fractures minimum horizontal stress falls below the BHP due to temperature changes, fractures may initiate and/or propagate [3,5,6] This applies to both vertical and horizontal wells [2]. Bay wells field for number of step-rate tests This shows the significant impact of a temperature difference between the formation and injected fluid on stress reduction, henceprocesses on TIF initiation and/or propagation propagation resulted fromand thermal is referred as Thermally
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
