In this paper, we discuss and describe our extensive experience with the widely applied and quite successful Cr(III)-carboxylate/acrylamide-polymer (CC/AP) gel technology for use in oilfield conformance-control, sweep-improvement, and fluid-shutoff treatments, along with briefly reviewing the gel technology's development. Chromic triacetate is the oftenpreferred chemical crosslinking agent used in conjunction with this polymer-gel technology. The CC/AP gel technology, which was conceived in late 1984, is characterized as having a robust gel chemistry and as being highly insensitive to petroleum reservoir environments and interferences. This gel technology has been employed in over 1,400 conformancecontrol treatments worldwide. Highlights of illustrative field applications and results involving the CC/AP conformance-control gel technology are presented. An overview of what a decade-plus of experience in developing and applying the CC/AP gel technology has taught us is discussed. This includes discussion of: classifying and distinguishing conformance problems and treatments, attributes of good candidate wells and well patterns for gel conformance-control treatments, requirements that must be met in candidate wells and well patterns in order to achieve success, gel treatment elements that must be successfully implemented in order to achieve success, guidelines where conformance polymer-gel treatments are most successfully applied, risks and pitfalls of gel conformance treatments, and quality control issues. AbstractThis study investigates how flow profiles in injection wells are modified when zones are not isolated during placement of gelling agents. Mathematical models are used to examine the degree of gel penetration and injectivity loss in zones of different permeability. Several conclusions are drawn that apply to reservoirs in which crossflow between layers does not occur. First, zone isolation is far more likely to be needed during placement of gels in unfractured wells than in fractured wells. Productive zones in unfractured wells may be seriously damaged if zones are not isolated during gel placement. Second, gel placement without zone isolation should cause the least damage to productive zones in unfractured wells when (a) the gelling formulation exhibits a low resistance factor during placement, (b) the water-oil mobility ratio is relatively high, (c) the most-permeable layer(s) are wateredout, and (d) the waterfronts are not close to the production well in the productive zones. Third, parallel linear corefloods overestimate the degree of profile modification that can be attained in radial systems. Fourth, chemical retention, dispersion and diffusion will probably not significantly mitigate injectivity losses caused by gel penetration into low-permeability zones. Finally, a need exists to determine the permeability and velocity dependencies of gelling-agent resistance factors and of gel residual resistance factors. Sorbie, K.S., Heriot-Watt U. Seright, R.S., New Mexico Petroleum Recovery Research Center Ab...

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractIn this paper, we discuss and describe our extensive experience with the widely applied and quite successful Cr(III)carboxylate/acrylamide-polymer (CC/AP) gel technology for use in oilfield conformance-control, sweep-improvement, and fluid-shutoff treatments, along with briefly reviewing the gel technology's development. Chromic triacetate is the oftenpreferred chemical crosslinking agent used in conjunction with this polymer-gel technology. The CC/AP gel technology, which was conceived in late 1984, is characterized as having a robust gel chemistry and as being highly insensitive to petroleum reservoir environments and interferences. This gel technology has been employed in over 1,400 conformancecontrol treatments worldwide. Highlights of illustrative field applications and results involving the CC/AP conformancecontrol gel technology are presented. An overview of what a decade-plus of experience in developing and applying the CC/AP gel technology has taught us is discussed. This includes discussion of: classifying and distinguishing conformance problems and treatments, attributes of good candidate wells and well patterns for gel conformance-control treatments, requirements that must be met in candidate wells and well patterns in order to achieve success, gel treatment elements that must be successfully implemented in order to achieve success, guidelines where conformance polymer-gel treatments are most successfully applied, risks and pitfalls of gel conformance treatments, and quality control issues.

This paper was ielacted for preaantation by an SPE Proaram Comtinee folloting revie;-of information contdned in en abetracf subtitted by tie author(s). Contents of the paper, aspr'aasna have not bean retiewd by the~ety of Petroleum Engineers and are subiect 10 co-on by the author(s). The metedaJ, se prasented, doss not nacessaiily reffwt any mm of the Society of Pefrdeum Engineas ik officee, or rnetiera. PaPars presented at SPE maetings are subjact to Wbficafion review by Edhonal Comnnftees of the Society of Ptimleum Engineers. uactronic raprodtion, distribution, or storage of any patl of this paper for comrciaf Furposes without tha Mftsn consent of tha Scciety of Petroleum Engineers is pruhiMted. Pem"aaion to reproduce in print is raatricted to an abstract of not mre than 300 wo~iffuafra'ons my not be c~ad. The tistract wst contain consdcueua ecknotiedgmnt of Meri and by tiom~he paper was presented. Write fibranan, SPE, P.O. Box 633836.~CbdSO& TX 7--3636. U.S.A. fas 01 .972-952-943S. AbstractIn this paper, we discuss and describe our extensive experience with the widely applied and quite successful Cr(III)carboxylate/acry larnide-polymer (CC/AP) gel technology for use in oilfield conformance-control, sweep-improvement, and fluid-shutoff treatments, along with briefly reviewing the gel technology's development.Chromic triacetate is the oftenpreferred chemical crosslinking agent used in conjunction with this polymer-gel technology.The CC/AP gel technology, which was conceived in late 1984, is characterized as having a robust gel chemistry and as being highly insensitive to petroleum reservoir environments and interferences. This gel technology has been employed in over 1,400 conformancecontrol treatments worldwide. Highlights of illustrative field applications and results involving the CC/AP conformancecontrol gel technology are presented. An overview of what a decade-plus of experience in developing and applying the CUAP gel technology has taught us is discussed. This includes discussion of classifying and distinguishing conformance problems and treatments, attributes of good candidate wells and well patterns for gel conformance-control treatments, requirements that must be met in candidate wells and well patterns in order to achieve success, gel treatment elements that must be successfully implemented in order to achieve success, guidelines where conformance polymer-gel treatments are most successfdly applied, risks and pitfalls of gel conformance treatments, and quality control issues. SPE49315

The removal of sulfate from injected seawater for waterflood and pressure maintenance operations has become widely accepted for reservoirs with sulfate scaling potential. The technology has been found to be exceptionally useful in deep water and subsea operations where scale controls using scale inhibition squeeze treatments become prohibitively costly. Twenty five sulfate removal facilities are now operating or being built off the cost of West Africa, Brazil, and in the North Sea. Experience with these existing facilities has identified methods to minimize the size of the sulfate removal facility with accompanying weight and space savings which often exceed the capital cost of sulfate removal system itself. Similar savings and trends have been identified by the availability and successs of auxiliary pre-filtration equipment. Operation cost reduction and improved reliability have been achieved by selecting raw seawater intake reduction and improved reliability have been achieved by selecting raw seawater intake locations, the re-design of sulfate removal system. The careful selection and evaluation of sulfate removal system components, including fine filtration and deaerators, have resulted in significant savings by extending membrane life up to twice the warranty period and by reducing operation costs of 25% than originally projected. Introduction The key component of a sulphate removal membrane process is sulfate removal membrane module or element, the component of the process which performs the removal of sulphate from the incoming seawater. The membrane process, within the membrane module, is depicted in Figure 1 where sulphate ions are selectively repelled off a membrane surface while allowing most of the remaining components of seawater to pass through the membrane. This membrane separation is achieved by placing the sulphate removal membrane in a "spiral wound configuration" which provides 400 + ft2 of membrane area to be placed in a module or cylinder 8" in diameter and 40" in length. As shown in Figure 2, the seawater passes from one end of the membrane element to the other end through "feed channel spacers". As the seawater passes over the membrane, the sulphate ions are rejected or repelled off the surface and discarded. The remaining seawater, containing predominantly sodium chloride, necessary to maintain stable reservoir clays, passes through the membrane itself and is transported to a product water tube by the permeate or product water channel spacer. The sulphate free seawater is then collected and used for injection into the reservoir.

Since the development of acrylamide-polymer/chromium(III)-carboxylate gels, a wide variety of field applications has demonstrated the utility and versatility of this system. Large volume injection well treatments for areal conformance, treatments for water/oil ratio reduction in producing wells, near wellbore treatments for effective squeeze treatments and the sealing of openhole wellbores as a completion tool will be reported. The initial treatments were pumped in the Big Horn Basin of Wyoming and in the Permian Basin of western Texas. These large volume treatments pumped into injection wells have added approximately 5 MMBO in reserves at a cost of less than $1.0 per STBO, to naturally fractured waterflood reservoirs. With this success, a program was initiated using the same polymer gel system in high water/oil ratio producing wells with a strong water drive. Water/oil ratios have been reduced from 300:1 to as low as 30:1 in several Big Lake Field wells of western Texas. Another form of the polymer gel system is used for near wellbore total shut-off as a substitute process for conventional squeeze cementing. This technology has been applied to shut off gas or water when pumped into an isolated interval. The same technology is routinely applied to seal the openhole curved section of re-entries for horizontal wellbore completions in the Yates Field Unit of western Texas.