Summary Many of the problems associated with the use of water-based fluids in drilling and completion operations are caused by incompatibilities between the fluids and the shales. Such incompatibilities may result in washouts, increased drilling costs (e.g., solids handling, rig time, dilution fluids), and shale sloughing during the drilling operation and after displacements to completion fluids or during gravel packing. One of the most important factors leading to an undesired result (either a premature screenout, thus a potential sand-control failure, or a higher skin) in water-packing of open holes is the presence of reactive shales in the interval to be gravel packed. Although there is a substantial amount of literature on shale inhibition with water-based drilling fluids, the importance of shale inhibition and the problems associated with shale reactivity during gravel packing remain largely unexplored. Furthermore, shale-inhibitor selection often relies on a comparison of the results from bottle-roll tests using shale samples in candidate fluid/inhibitor pairs (drilling or completion fluid) and on tests measuring the degree of shale swelling. While these tests are highly functional, they can provide information only on the relative performance of fluids, and their relevance to gravel packing is questionable because these tests do not simulate the conditions experienced during such treatments. This paper presents guidelines on selection methodology of shale inhibitors for use in gravel-packing applications on the basis of the data available in our respective companies, including a comparison of results from conventional bottle-roll tests to those from flow through predrilled holes in shale core samples. Recommendations are made depending on brine type and density, type of shale, temperature, fluid exposure history, and environmental considerations. Introduction Openhole-horizontal completions have emerged as a cost-effective means of exploiting deepwater reservoirs, many of which require sand control. Gravel packing is the preferred sand-control technique for such environments where remedial treatment costs are prohibitively high (Price-Smith et al. 2003). Two techniques have been employed for gravel packing open holes with varying degrees of success: alternative path and water packing. The focus of this paper will be to address one of the problems considered to be a key risk factor in successful implementation of water-pack treatments. The risks associated with openhole water packing completions can be summarized asSwabbing, which has been addressed through the development of antiswab-tool systems (Vozniak et al. 2001)Exceeding fracturing pressure--during the beta-wave, which has been addressed with the development of beta wave attenuators (Coronado and Corbett 2001) or use of low-density gravel, allowing lower pump rates without the concern for gravel settling in the work string (Pedroso et al. 2005)--during the alpha wave in environments with narrow-frac window, that in some cases may be addressed through the use of low-density gravel (Pedroso et al. 2005)Filter-cake erosion, (the conditions under which this becomes a risk remain to be determined) (Gilchrist et al. 1998)Reactive shales that may either collapse/slough or disperse in the carrier fluid; the former may lead to a premature screenout because of blockage of the annulus, and the latter may result in a low-permeability gravel pack because of shale and gravel intermixing (Gilchrist et al. 1998; Corbett and Winton 2002; Mathis et al. 2000; Murray et al. 2003) Shales are characterized by high clay content, low quartz content, and low permeability (a byproduct of the small-clay size). On the basis of numerous factors, shale can react catastrophically when exposed to some aqueous fluids. These factors include downhole-stress states, native-fluid composition, mineralogical composition, and interaction with the completion-fluid chemistry and properties. It is important to note that these factors also determine the time a shale will take to fail when exposed to a given completion fluid, and hence, a shale that has survived the drilling process may still fail during the post drilling activities leading to the gravel pack (Dickerson et al. 2003). It is possible to minimize and even eliminate this adverse reaction by selecting a suitable completion fluid. This selection may involve choosing the correct brine type and additives to increase the inhibitive qualities of the completion fluid. The literature on the subject of shale compatibility with muds is vast. The reactivity of shales to aqueous muds with various additives has been well studied (Chenevert 1970; O'Brien and Chenevert 1973; van Oort 1997). However, the effect of completion fluids has not been studied extensively. The purpose of ensuring proper shale inhibition with drilling mud is to address shale reactivity concerns such as cuttings disintegration, wellbore instability during drilling, and bit balling (van Oort 1997). On the other hand, a completion fluid must be formulated to inhibit shale to maintain wellbore stability after drilling (e.g., during mud displacements or gravel packing) in reactive-shale sections (Gilchrist et al. 1998; Mathis et al. 2000) and to prevent erosion of weakened shales during gravel packing (Ali et al. 1999). Various testing techniques have been proposed in the literature to characterize the inhibitive properties of drilling fluids (Roehl and Hackett 1982; RP 131 2004; Bailey et al. 1994; Mondshine 1973). Because these tests were designed specifically for drilling applications, their direct applicability to water packing, subsequent to water-based drilling, is questionable. Of these testing techniques, the wellbore-simulator tests first described by Darley (1969) and further developed by Bailey (1994) and Gaylord (1983) are more useful for evaluating inhibitor effectiveness in gravel-pack applications, as is also suggested by Corbett and Winton (2002). By exposing various fluids to boreholes drilled in shale cores, Darley (1969) showed the different modes of failure and correlated them to the effect of tectonic stresses, mineral content, age of shales, and flow of mud through the shale borehole. Gaylord developed this testing to look further at the effect of fluid-mechanical parameters on borehole erosion and concluded that erosion will be most pronounced if the particular shale/fluid system is reactive. In addition, hole erosion increases with increasing shear stress and is exacerbated under turbulent conditions. The tests done by Bailey (Price-Smith et al. 2003) look only at the effects of reactivity by shale but corroborate the mechanism of weakening of the shale and subsequent erosion by flow. This is evident in their tests through increased wellbore diameter resulting from erosion. On the basis of this information, a similar test will be used in this work to evaluate completion-brine inhibition. It is the objective of this paper to provide guidelines on selection methodology of shale inhibitors for use in gravel-packing applications. The paper is organized as follows. First, a brief description of the typical critical stages in a gravel-packed completion is given. This is followed by a discussion of the current testing methodology typically employed in the industry. Next, the experimental techniques and materials used in this study are presented, followed by the results from hot-roll and drilled-core experiments. Finally, conclusions are drawn.
Many of the problems associated with the use of water based fluids in drilling and completion operations are caused by incompatibilities between the fluids and the shales. Such incompatibilities may result in washouts, increased drilling costs (solids handling, rig time, dilution fluids, dilution fluids), shale sloughing during the drilling operation and during the drilling operation and after displacements to solids-free completion completion fluids or during gravel packing. One of the most important factors leading to an undesired result (either a premature screenout, thus a potential sand control failure, or a higher skin) in water-packing of open holes is the presence of reactive shales in the interval to be gravel packed. Although there is a substantial amount of literature on shale inhibition with water-based drilling fluids, the importance of shale inhibition and the problems associated with shale reactivity during gravel packing remain largely unexplored. Furthermore, shale inhibitor selection often relies purely on a comparison of the results from bottle roll tests using shale samples in candidate fluid/inhibitor pairs (drilling or completion fluid) and on tests measuring degree of shale swelling. While these tests are highly functional, they can only provide information on the relative performance of fluids, and their relevance to gravel packing is questionable, as these tests do not simulate the conditions experienced during such treatments. This paper presents guidelines on selection methodology of shale inhibitors for use in gravel packing applications based on the data available in our respective companies, including a comparison of results from conventional bottle roll tests to those from flow through predrilled holes in shale core samples. Recommendations are made depending on brine type and density, type of shale, temperature, fluid exposure history, as well as environmental considerations. Introduction Openhole horizontal completions have emerged as a cost-effective means of exploiting deepwater reservoirs, many of which require sand control. Gravel packing is the preferred sand control technique for such environments where remedial treatment costs are prohibitively high.1 Two techniques have been employed for gravel packing open holes with varying degrees of success: alternate path and water-packing. The focus of this paper will be to address one of the problems considered to be a key risk factor in successful implementation of water pack treatments. The risks associated with open hole openhole water packing treatments completions completions can be summarized as:Swabbing, which has been addressed through the development of antiswab tool systems,2Exceeding fracturing pressureduring the beta wave, which has been addressed with the development of beta wave attenuators3 or use of low density gravel allowing lower pump rates without the concern for gravel settling in the work string,4during the alpha wave in environments with narrow frac window, which in some cases may be addressed through the use of low density gravel,4Filtercake erosion, which remains as the biggest uncertainty,5Reactive shales which may either collapse/slough or disperse in the carrier fluid; the former may lead to a premature screenout due to blockage of the annulus and the latter may result in a low permeability gravel pack due to shale and gravel intermixing.5–8
Shale-gas reservoirs are becoming an increasingly significant percentage of the global tight-reservoir landscape. Three questions reflect this increasing dominance but are applicable overall to tight formations.• Is the long multistage-fractured horizontal well into which millions of gallons of water are pumped downhole with only a third of the contacted reservoir propped open the most efficient way to produce the reservoir?• Is the long multistage-fractured horizontal well the endgame solution to Master's Resource Triangle?• If the equations set forth by Darcy and Young/Laplace are valid, does contacting a large amount of the formation with only water constitute stimulation of the reservoir?Capillary pressure is significant in tight reservoirs. Stimulation-fluid invasion into smaller pore diameters and invasion of proppant-free stimulation fluid into both induced fractures and dilated natural fractures will have an effect. Production-decline rates and long-term health of wells (improved fluid flow or degree of formation damage) in tight reservoirs will depend on how capillary forces are managed in the reservoir.Log-normal large volumes of hydrocarbon found in tight reservoirs are difficult to develop because of constrained drainage areas, complicated petrophysics, lithology, and formation heterogeneity. These difficulties, complexities, and heterogeneities dictate planning of drilling, completion, and stimulation specific to the well in question. They also dictate continued advances in knowledge and technology if the majority of the hydrocarbon asset is to be produced effectively.Early production levels will be dependent on the length of propped fracture from the wellbore that has actually cleaned up and this contributing to hydrocarbon flow.Our industry needs to make advances in: real-time measurement; post-fracture monitoring with production analysis; identifying sweet spots, then placing perforations to create complex conductive fractures; innovative proppants and proppant-placement techniques in primary and complex fracture geometries; fluid recovery; formation-damage control and permeability enhancement; proppant transport with less-damaging stimulation fluids; and environmentally responsible drilling, completion, and production services.
QWUM199S. SC6S9 of P@deum EIVeem l.c. Thm papef was pqared for pre!iemtabcmat Uw lnWnatonal Cardemnca m tieakh, Safety & Envk rcwnent IWM In NwOrkaK I_ouwrma, 912JwM 1990 Tfus M V@ sekmd fcr pw.zmtilmn by an S$E Pqram Oxmrmes fokmmg rwww of mutmn mmxwd m an abwwa wbmtmd W me author(s) Cc@Mts~the FOpef, as pre$emed, Me not bwn rrr.ww by me %cI@ C4 PUK4Bum Eng!nB3s and are w-10 CXXIKBOO by the author(s) The r7WWal, US ve50nfd, doss M -"" '""W 'W%%.$%RY$ Z POtrohwm Engmears us Omw~, or mentmm paws presented at pubkaton rww,v by Edmrral Camnfite?s d the 5U%KV d P@c+?um EngIwers PerrmssIcII 10 COPY 6 restJD2edto an abstract ot not mare than 3X '.uxds lllusbatIOns may not hscopmd The amtrm 2:.:FE,%EYmsTd%7e=L"Y2, R%%%=?" '" AbstractAs the oilfield industry strives to globally sustain continuous improvement of environmental and quality performance, eompaoies have come to realize Total Quality Environmental Marugement (TQEM) is essential in product mearck development manufacturing and sesvices. As our industry endeavors to continuously improve, more emphasis is being placed upon the management systems we apply such as 1S0 14000 and 1S0 9000. These standards arE tools for improving environmental and quality performance, meeting crrstomcr requirements, and increasing profitability.This pa~r presents actual examples of the successfid integration of environmental and quality mgcment systems into an operational TQEM system. Also presented arc pilotstudy evaluations of the dmfl 1S0 14000 standards by two certified 1S0 9000 facilities.Examples of continuous improvement and cross-functional teams as means to merge environment and quality management into the functions of process control, corrective and preventive actiom document control, and waste management are presented.Results and improvements from facilities involved with TQEM are discussed along with their strategies and progress in consolidating tk environmental and quality programs into a single, viable management system. The case histories from various facilities demonstrate the implementation of TQEM and how TQEM promotes a cleaner environment, reduces costs, ecm-serves energy and raw materials, minimizes pollutants and wastes, and reduces redundant paperwork.
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.
customersupport@researchsolutions.com
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.