When sand control is required in production or injection wells, one of the key design criteria is that the sand control should allow those "fines" present to pass, whilst retaining "sand". However the definition of "fines" is not universal and some arbitrary size and/or compositional definitions are often used that could potentially lead to inappropriate sand control design. The fines in any rock sample are usually categorized as that portion of the rock which passes through a ~45 micron sieve. This is a convenient cut-off point for laboratory evaluations as it represents the finest commonly used sieve. It has become routine to use the percentage of fines in a rock sample as one of the key parameters for sand control type selection and specific screen selection. In a coarse-grained, well-sorted sand, particles "less than ~45 microns" may well represent that part of the rock that can move through the pore throats. However, significant variation exists in oil and gas reservoirs and this should be considered in order to obtain an appropriate definition of what constitute fines for a specific reservoir. From a reservoir perspective, the preferred definition of "fines" is that part of the rock that can move through the pores of the intact rock. Using pore throat size measurements and estimates, it is possible to develop a much more rigorous mobile fines size for any formation. Coupled with grain size analysis (which should include some laser analysis of the finer fraction) the true "fines" can be quantified for any given sand. The sand control selection is made using this new definition of fines, leading to optimum and tailored selection, based on science rather than convenience or tradition. For sand control performance evaluation it is not only the mobile reservoir fines that are a concern. Should the formation fail into an annulus then the rock components may re-sort in the annulus and bring about high skins and possible screen plugging. Here, the sizing of the fines that are of concern will be different. It has been convenient to adhere to somewhat arbitrary particle size distribution cut-off points when selecting sand control. When informed with an improved understanding of the petrology, particle behaviour, impact of their movement, and the interaction between the formation and the well, while it is being both constructed and produced it is proposed that we can improve the selection process.
Definitive rock strength data for sand failure evaluation are only available from tests on core plugs, however coverage is limited and core condition and geometry may preclude plugging. This paper presents results from a non-destructive core strength index tester that is less destructive than the Schmidt Hammer and less intrusive, easier, faster and cheaper than the core scratch tester. The portable index hardness tester measures and compares the impact and rebound velocities of a small steel ball after its collision with a rock surface to determine its hardness which in turn reflects the relative strength of the rock. The tester is run at regular intervals along the surface of the core to provide additional data that complement and enhance core rock mechanics data.Several field examples are presented which illustrate the use of the index tester to optimise core sample selection, evaluate controls on rock strength, and to calibrate and constrain the development of wireline log-based strength models. Importantly, cases are included to highlight exceptions where the tester can produce misleading and even contradictory results.The integration of index test results with core plug data and log analysis enables development of more robust rock strength models. The methodologies and techniques developed in this work have in turn enabled more accurate sand failure estimates that represent key tools in the development of effective sand management strategies for the reservoir life cycle for a variety of fields throughout the world.
Sand management is an issue pertinent to all those disciplines responsible for maturing a project. It requires leadership from the asset owner, expertise from the specialists and top quality equipment from the vendors. Excellence must span all the stages of field development for, like many aspects of well construction, "9 out of 10" is usually not good enough. For this reason guidance is proposed for management and design of sand related projects.The sand management team needs to define the tasks and activities to achieve established and shared objectives, those objectives being to achieve the required well productivity, longevity and functionality.Although these objectives are few, they can only be achieved through careful execution of the various tasks and associated activities. Many tasks are entwined between two or three objectives and need to be done in a particular order. This paper proposes a methodical workflow framework to achieve this.In many cases the answers to design questions are dispersed amoungst an unmanageable number of papers, manuals, guidelines, training and conference proceedings and this paper goes some way to draw the threads together for some of the common design issues. In some areas, work is still to be done by our industry to clarify equipment specification, standardising definitions, test methods, and modeling techniques. SPE 114781Sand managers are expected to advise on important questions for the field development: How should we design these wells? For how long will they perform? When will sand be produced and what will it do? Can we constrain future water or gas breakthrough?The industry demonstrates its recognition of these questions with at least two annual conferences dedicated to the subject, complemented by others such as the Formation Damage Symposium, APPEA, SPWLA and APOG. However, particularly to the newcomer, assimilating so much information is becoming impractical. At least 400 papers have been written on sand management with test procedures, guidelines, equipment and specifications being continually revised.When designing for sand, it will be seen that "the devil's in the detail". Unfortunately despite our learning, important testing procedures are inconsistent across the industry, concepts are understood in different ways, we work with legacy guidelines where the supporting background is obscure and with published specifications that don't withstand heavy scrutiny.With this challenge to acquire the knowledge, the aspiring sand manager may neglect the importance of an enabling environment and methodology. Therefore, this paper answers at least some questions regarding what we are sure of, proposing good practice for the management of a sand related project, the importance of which is often underestimated. Objectives, tasks and activities are placed within a recognized structure, thereby defining a methodology to progress a project. Certain selected test procedures, concepts, legacy guidelines and specifications are scrutinized.While strong in some areas of this discipli...
TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractUnderstanding and predicting fracture propagation behaviour in a geotectonically complex, layered reservoir presents major challenges.In particular, an accurate prediction of vertical fracture extension in horizontal injection wells is fundamental to the overall waterflood injection performance assessment.Water injection in an open hole horizontal well in a low permeability formation may generate one or multiple fracture planes depending principally on the orientation of the well with respect to the in situ stress field, as well as the combined effects of high injection rates, low injectivity and stress reduction due to thermal effects.Conventional fracture generation prediction in horizontal sections considers predetermined areas where the fractures will propagate. In an open hole environment, the number of fractures that will be generated over time is often too complex to allow accurate prediction.A novel methodology, based on a fracture energy dissipation approach, has been developed to overcome the problems associated with conventional models in horizontal open hole sections.This strategy integrates the field geomechanical model with a commercial transient fracture simulation model. The simulation model was used to predict the vertical extension of the fractures by studying the energy dissipation that takes place under specific injection conditions. A relationship has been found between the initiation area, injection flow rate and the non-dimensional vertical propagation factor that can be used to predict (and ultimately control) vertical fracture growth even in heterogeneous sandshale sequences. The introduction of selective initiation areas along the horizontal well section will radically improve the control of fracture vertical extension.Using this methodology, it is possible to design and evaluate completion strategies, which optimise fracture energy dissipation and fracture containment performance in open hole horizontal injection wells in low permeability formations.
TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractSand production is a major issue facing many operators in the mature Southern North Sea gas fields. Historically, sand control completion decisions have often been based on the assumption that sand control will occur and have been constrained by the restrictions imposed upon sand entering the gas transport pipeline. The inherent conservatism of this approach leads to significant increases in completion costs and misses potential productivity gains.A holistic sand management strategy has been developed for the Southern North Sea to challenge the conservative paradigm. This is based on a complete understanding of SNS reservoir rock properties and sand control completion performance in gas wells and has been tuned by learnings from SNS and analogue fields. It couples sand failure prediction, methodical and structured sand control selection (including consideration of production performance, longevity and risks) with novel solids lifting and erosion assessment models to better quantify the risk and consequences of sand production on wells and facilities. Key selection criteria are utilised rather than an arbitrary decision based on limited and often unaudited data. The role of an asset focal point with clear ownership of all relevant sand production data and issues is fundamental to the success of the integrated strategy.Tools are available to predict when, where and even how much sand will be produced; how much sand will be lifted to surface; and how much erosion it will cause. Methodologies are available to evaluate and rank the available sand control techniques in a consistent and systematic manner.This more systematic and integrated approach to sand management has enhanced well productivity and reduced completion costs without compromising sand management or exceeding sand production constraints. Challenging sand management convention in the demanding environment of the Southern North Sea compels operators to use these methodologies to much greater effect.
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.