In Nederland worden woekerende waterplanten geoogste om de waterwegen open te houden. Het is de verwachting dat door verbeteringen in de waterkwaliteit de groei van deze planten nog verder zal toenemen. Waternet, het bedrijf wat verantwoordelijk is voor de waterwegen in en rond Amsterdam en zich richt op de hele watercyclus, wil de geoogste waterplanten nuttig en duurzaam gebruiken. Een van de opties, die daarbij onderzocht is betreft TORWASH, een technologie die door ECN (Energieonderzoek Centrum Nederland) ontwikkeld wordt. TORWASH is een natte torrefactie technologie, die natte, zoute biomassa omzet in een vaste bio-brandstof die geschikt is als brandstof voor energiecentrales. In dit rapport worden onderzoeksresultaten gepresenteerd die zijn verkregen met Waterpest (Elodea nuttalii) en Cabomba (Cabomba caroliniana). De monster zijn geoogst aan het einde van de zomer van 2012 en direct naar ECN gebracht om daar te worden verwerkt. Het materiaal is gehakseld en de slurries die daaruit resulteerden zijn onderworpen aan TORWASH testen in een autoclaaf. Het natte product is gefilterd en mechanisch ontwaterd. Na een set verkennende proeven zijn de optimale condities vastgesteld om de experimenten op te schalen en uit te voeren in de 20 liter autoclaaf. Van deze grotere tests zijn massabalansen opgesteld en is de distributie van relevante elementen bepaald, zoals kalium, chloor, stikstof en fosfor. Het uitgeperste materiaal is tevens onderzocht op brandstofkwaliteit. Beide waterplanten blijken een geschikte grondstof te zijn voor het TORWASH proces. Het hakselen tot een slurry met 90% water resulteert in een vermindering van het volume met een factor 4. Dit alleen al kan leiden tot aanzienlijke besparingen op de logistieke kosten voor het afvoeren van de waterplanten. Na het hakselen is de slurry direct geschikt om te TORWASHen. Er is geen toevoeging van water nodig. Na de TORWASH stap kan het product mechanisch ontwaterd worden tot 70% droge stof. De massaopbrengst (aan droge stof) ligt rond 50%, wat een normale waarde is voor TORWASH. Alkali en chloor worden efficient verwijderd tot een niveau wat vergelijkbaar is met dat van houtchips zonder bast. Het uitgeperste product is geschikt voor meestoken in kolencentrales, maar het chloorgehalte is nog net een fractie boven de IWPB standaard voor I2 industriele houtpellets. Het is de verwachting, dat een eenvoudige nawas-stap dit kan verhelpen. De uitgeperste producten bevatten 20-40% as, wat veel meer is dan hout of steenkool. Veel van deze as is echter silica omdat bepaalde elementen selectief worden uitgewassen. Het hoge asgehalte beperkt meestoken in kolencentrales, maar het blijft mogelijk om de bio-brandstof in wervelbedinstallaties of roosterovens te gebruiken. Het is dus wel een geschikte brandstof, maar voor sommige toepassingen een minder aantrekkelijke brandstof.

Abstract The need for a fit-for-purpose cement sheath was recently emphasized in the HPHT Shearwater Field when annular pressures were observed on all but one of the production wells, either immediately or during the completion phase. Such annular pressures may result in an inability to produce the reservoir, which fully erodes the value of the asset. The main objective of a primary cement job is to prevent formation fluids from migrating into the annulus so that the reservoir can be produced safely and economically. To achieve this objective, as a first step, cement slurry should effectively displace the drilling fluid in the annulus. The set cement sheath should then withstand the stresses induced by the well events and maintain integrity during the life of the well. For the Shearwater Field, a rigorous design method was used to evaluate the integrity of the cement sheath as a function of its properties and formation characteristics. The design procedure was based on finite element modeling and simulated the sequence of events starting from the drilling phase, including cement hydration, well completion, and production. This paper discusses ways to improve cement designs in the Shearwater Field. The methodology developed was used to optimize the design of future Shearwater wells, resulting in the specification of improved cement systems/methods. The criteria used to evaluate the cement sheath performance are discussed, as well as the effects of well events on cement systems for reducing the risk of damage. The specification from this analysis was implemented in the field, and the optimized cement sheath withstood the stresses from well completions and other events. The new well is on production and all indications are that no annular pressure problems exist. Therefore, this design process can help improve the economics of constructing and producing oil and gas wells, resulting in a cost-effective life-cycle design. The process can also reduce health, safety, and environmental (HSE) risks because it minimizes the potential for zonal isolation failures.

Abstract One of the main objectives of a primary cement job is to prevent formation fluids from migrating into the annulus. To achieve this objective, the cement sheath should withstand the stresses induced by the various well operations and maintain integrity during the life of the well. However, the majority of the cement design programs in the industry today consider only the slurry properties and do not assess the effect of the mechanical properties of the cement sheath on the final well design. A design procedure has been developed to estimate the risk of cement failure as a function of cement sheath and formation characteristics and well loading. A few examples of well loading are pressure testing, well completion operations, hydraulic fracturing, and hydrocarbon production. The design procedure is based on a finite element analysis and simulates the sequence of events from drilling through cement hydration, well completion, and production operations. The cement failure modes simulated are debonding, cracking, and plastic deformation. The cement is assumed to behave linearly as long as its tensile strength or compressive shear strength are not exceeded. The material modeling adopted for the undamaged cement is a Hookean model bounded by smear cracking in tension and Mohr-Coulomb in the compressive shear. Shrinkage and expansion of the cement are included in the material model. The need to design a fit-for-purpose cement sheath is accentuated by the sustained casing pressure observed on a number of wells after they were put on production and on some HPHT wells after the displacement fluid was changed over to a well-completion fluid. The pressure in the annulus side sometimes results in an inability to continue further operation. Applications are discussed and examples are provided. From the processes reviewed in this paper, one can estimate the risk of failure of various cement systems and select a fit-for-purpose system that will minimize the overall cost. This process should improve the economics of constructing and producing oil and gas wells (cost effective life cycle design) and also improve safety because zonal isolation failures may be reduced.

Abstract Natural gas is one of the cleaner sources of energy, and our challenge is to produce it safely and economically. The extreme operating conditions that occur in gas-storage and gas-producing wells could cause the cement sheath to fail, resulting in fluid migration through the annulus. Designing cement sheaths that can withstand the stresses induced by the various operations and maintain integrity during the life of the well will help minimize the risk of cement failure. A design procedure has been developed to estimate the risk of cement failure as a function of cement sheath and formation properties and well-stress loading. A few examples of the loading are cement hydration, pressure testing, gas injection, and gas production. The design procedure simulates the sequence of events from drilling to cement hydration, hydraulic fracturing, injection, production, etc. Cement failure modes simulated are de-bonding, cracking, and plastic deformation. An appropriate nonlinear material model, including cracking and plasticity, is used in the analysis. The sustained casing pressure observed on a number of wells after they have been put on production emphasizes the need to design a cement sheath that will maintain integrity during the life of the well. Field cases and applications are discussed. From the process discussed in this paper, one can estimate the risk of failure of different cement systems and select the system that can help minimize the overall cost. The process should improve the economics of constructing and producing gas and oil wells and also improve the safety due to the reduced risk of zonal isolation failure.

This article is a synopsis of paper SPE 56536, "Design Approach to Sealant Selection for the Life of the Well," by Martin Bosma, SPE, Shell Intl. E&P; Kris Ravi, SPE, Halliburton European Research Center; and Willem van Driel and Gerd Jan Schreppers, TNO Building and Construction Research, originally presented at the 1999 SPE Annual Technical Conference and Exhibition, Houston, 3-6 October.

The scid mutation occurred in the C.B-17Icr (C.B-17) inbred strain, an immunoglobulin heavy chain (Igh) congenic partner strain of BALB/cAnlcr (BALB/c) . The C.B-17 strain was derived from the 13th backcross generation of the original C.B stock of M. Potter. C.B-17 mice are not known to differ from BALB/c mice except that a portion of their chromosome 12 comes from the C57BL/Ka strain and includes the C57BL/Ka Igh locus and other closely-linked genes.

Antibody cell clones of (C57BL/6 C3H/HeJ) F 1 mice directed against the haptens, poly-O-acetyl-d-serine (poly-ser) and poly-d-alanine (poly-ala), were evaluated with the aid of a cell transfer system and a modified plaque assay. When antibody responses to poly-ser or poly-ala were initiated by a few precursor cells, unequal associations of a given antibody specificity with one of two parental antibody allotypes became apparent: namely, poly-ser specific clones of C3H/HeJ allotype were more frequent than those of C57BL/6 allotype, whereas poly-ala specific clones of C57BL/6 allotype were more frequent than those of C3H/HeJ allotype. The degree of these unequal associations could be accentuated when both poly-ser and poly-ala specific clones were induced with proteins bearing random copolymers of O-acetyl-d-serine and d-alanine (ser-ala). In this instance the proportion of clones which were of C57BL/6 allotype was greater than that obtained with either homopolymer hapten. We interpreted these results as consistent with the following: 1) that closely-linked genes encoded for the two distinct portions of mouse immunoglobulin heavy-chain that determine allotype (constant region) and combining site specificity (variable region); and 2) that more of the immunoglobulin structural genes of the C3H/HeJ allelic chromosomal region could encode for antibodies to the poly-ser hapten than those of the C57BL/6 allelic chromosomal region, while the converse seemed true for antibodies specific to the poly-ala hapten.

In “The Clonal Nature of Antibody Formation: II. Characteristics of Antibody Cell Clones Specific for Poly-O-Acetyl-d-Serine and Poly-d-Alanine” by M. Bosma and G. Davis in the September 1972 issue of the Journal of Immunology, Volume 109, Number 3, page 489, the precipitin arcs in Figure 1 did not show clearly. The illustration is produced again here to indicate what was in the original photograph. In “Additional Immunochemical Relationships of Capsular Polysaccharides of Klebsiella and Pneumococci” by Michael Heidelberger and Wolfgang Nimmich in the December issue of the Journal of Immunology, Volume 109, No. 6, page 1341, Table III, footnote v should read, “Supernatants + K32 precipitated 698 µg N; intact serum gave 804 µg N at the level used.” Footnote x should read, “Supernatants + K34 gave 31 µg N out of 56 at the level used. Antiserum gave 39 µg N with streptococcal group Fz1 substance (30); supernatants + K64 gave 32.”

With the aid of a cell transfer system using F1-hybrid spleen cells of syngeneic mice, poly-d-alanine (poly-ala) antigen and a modified antibody plaque assay, we were able to rigorously test and confirm the clonal nature of antibody formation. Our results showed that when x-rayed mice were repopulated with relatively small numbers of spleen cells followed by two immunizations, only a few animals produced antibodies to poly-ala and in the spleens of most of these responder mice only one of two allelic gene regions determining 7S antibody phenotype (B or C allotype) was expressed. On the other hand, when relatively large numbers of spleen cells were transferred to x-rayed mice followed by two immunizations, all recipients responded to poly-ala and expressed both antibody-forming cells of B and C allotype. The all-or-none response characteristics at limiting spleen cell doses were amenable to Poisson statistics suggesting that some mice were repopulated by descendants of a single poly-ala-sensitive precursor unit, i.e., by an individual clone of antibody-forming cells. The application of Poisson statistics to mice expressing only one marker allotype confirmed this interpretation. The number of mice expected to be repopulated by a single poly-ala-sensitive precursor unit correlated very well with the number of responder mice expressing only one allotype. Thus antibody specificity and allotype must be transmitted together in cell lines and thereby characterize individual clones. The total number of prospective clones of poly-ala specificity was estimated to be about 150 per young adult mouse. The calculated size of a given individual clone was 20,000 to 50,000 synthesizing cells which represented about 14 to 16 cell divisions.