Initial Cut Research Articles

Fracture Permeability and High Initial Water Cut in a Carbonate Gas Reservoir: ABSTRACT

Waveland field in Hancock County, Mississippi, produces gas and condensate from the Lower Cretaceous Mooringsport Formation at approximately 13,400 ft. Total gas reserves have been estimated at 256 bcf. The reservoir is a fractured lime packstone, containing milliolid and orbitolinid foraminifers, mollusk fragments, and echinoderms. Core plug permeability is low, commonly below 1 md, yet productive wells flow at rates of as much as 8,000 MCFGD. Thus, fracture permeability is an important reservoir property. Short-term flow tests can be misleading, as productive wells may initially produce an uneconomically high water cut for several days. The trap is a south-southwest-plunging anticline with no apparent structural closure to the north. A map of averaged, thickness-weighted porosity values for productive stratigraphic intervals indicates that porosity does not decrease across the northern limit of production. In order to compare the productivity potential of zones with varying porosity and water saturation, Buckles Numbers (product of porosity and water saturation) were mapped for zones within the productive stratigraphic interval. Averaged, thickness-weighted Buckles Numbers indicate that productivity potential does not decline across the northern limit of the field. Thus, it is concluded that the northern (updip) extent of effective fracture permeability controls the northern limit of production at Waveland field. High initial water cut indicates that water is in the fractures and gas and water are in the matrix. The presence of water in fractures adjacent to rock with much narrower effective pore-throat radii is a normally unstable situation, as capillary pressure would be expected to result in the matrix imbibing water and releasing gas to the fractures. It is proposed that fracturing occurred after hydrocarbon migration and that there is little or no fluid exchange between fractures and matrix prior to wellbore drawdown. Waveland is an example of a field where limits of productivity are controlled by permeability rather than by porosity, hydrocarbon saturation, or trap geometry. Buckles Numbers maps are a useful tool for describing productivity potential of similar fields. End_of_Article - Last_Page 282------------

Hormone processing and membrane-bound proteinases in yeast.

A search for maturating peptidases of the precursor protein of the mating hormone (pheromone) alpha-factor of Saccharomyces cerevisiae was performed using short model peptides representing those sequences of the precursor protein, where cleavage is thought to occur in vivo. This search was done in a mutant lacking several of the unspecific vacuolar peptidases. The chromogenic peptide Cbz-Tyr-Lys-Arg-4-nitroanilide led to the detection of a membrane-bound enzyme called proteinase yscF. Cleavage of the synthetic peptide derivative occurs after the basic amino acid pair, a proposed signal for hormone processing. Optimum pH for the reaction is 7.2. The enzyme does not cleave after single basic amino acid residues indicating that it is distinct from trypsin-like proteinases. Proteolytic activity is enhanced by Triton X-100. The enzyme is strongly inhibited by EGTA, EDTA and mercurials but insensitive to phenylmethylsulfonyl fluoride. The enzyme activity is strongly dependent on Ca2+ ions. In a mutant (kex2), which accumulates an over-glycosylated alpha-factor precursor, no proteinase yscF activity can be found. Membrane-bound peptidase activity possibly involved in removal of the arginyl and lysyl residues remaining at the carboxy terminus of the alpha-factor pheromone peptide after the initial cut of the precursor molecule could be identified by using the model peptides Cbz-Tyr-Lys-Arg and Cbz-Tyr-Lys.

Location of an immunizing determinant within polypeptide VP1 of type O aphthovirus.

VP1 is the only structural polypeptide of aphthovirus able to stimulate the production of neutralizing antibody. The region of VP1 responsible for this activity was located by testing various proteolytic fragments of VP1 for their ability to compete for virus-specific antibodies in serum raised against the intact polypeptide. No antigenic activity could be detected in VP1 fragments isolated from trypsin-treated virus. Controlled digestion revealed that trypsin cleaved VP1 in four places in a preferred order, whereas chymotrypsin cut at a maximum of two sites. The initial cuts by the two proteases were made very close to each other, and in each case resulted in a greatly reduced affinity of the VP1 fragments for virus-specific antibodies in anti-VP1 serum. In contrast, aphthovirus was resistant to Staphylococcus aureus V8 protease, and treatment of isolated VP1 with this protease generated a peptide of mol. wt. 8500 which competed efficiently with virus for antiserum to VP1 and for an absorbed antiviral serum specific for trypsin-sensitive sites. The results indicate that these antisera interact specifically with aphthovirus at a single antigenic determinant located on VP1 approximately two-thirds of the way along the polypeptide sequence.

Regenerating Southern Appalachian Mixed Hardwood Stands with the Shelterwood Method

Abstract Shelterwood cuts, with understory treatment by cutting or herbicide application, can be used to regenerate southern Appalachian hardwoods. Cuts with residual basal area ranging from 25 to 66 square feet per acre and overwood retained from 5 to 13 years established desirable, well-stocked stands. However, species composition was essentially the same as in clearcuts with intolerant species, especially yellow-poplar, dominating. Oak regeneration did not benefit from either higher residual basal area or longer periods of overstory retention, even though oaks were prominent in the overstories of all stands. Only where larger oak advance reproduction was numerous before the initial cut did oaks become a prominent component of the new stand.

EFFECTS OF INITIAL HARVEST DATE ON DRY MATTER YIELD, IN VITRO DRY MATTER DIGESTIBILITY AND PROTEIN IN TIMOTHY, TALL FESCUE, REED CANARYGRASS AND KENTUCKY BLUEGRASS

Timothy, tall fescue, reed canarygrass and Kentucky bluegrass plots were harvested at weekly intervals from the vegetative stage through to seed maturity for 3 yr in order to evaluate the effect of harvest and species on nutrient production. The forage of the early harvest regimes was cut after 5 wk of regrowth and all plots were harvested in the fall. In vitro dry matter digestibility (IVDMD) values ranged from above 80% down to 45%, with an average rate of decrease during June of 0.74, 0.84, 0.85 and 0.45% per day in timothy, tall fescue, reed canarygrass and Kentucky bluegrass, respectively. Similarly, crude protein (CP) in first-cut forage ranged from 28% to 6% and had respective decreases of 0.47, 0.40, 0.39 and 0.28%/day. Regrowth forage in the midsummer and fall harvests averaged from 63 to 59% IVDMD and from 16 to 20% CP, respectively. With the exception of reed canarygrass, delaying the initial cut resulted in continued increases in total annual dry matter (DM) yield, significant increases in total IVDMD yield until flowering, and decreases in total CP yield from stem elongation onwards. Reed canarygrass reached its optimum CP yield at early heading and had significant increases in IVDMD yield until the flowering stage. Harvesting all forages at the stem elongation stage substantially reduced the yield of DM, IVDMD and CP. Although most of the DM was obtained in the initial harvest, almost half of the total CP was obtained in the final harvest.Key words: Timothy, tall fescue, reed canarygrass, Kentucky bluegrass, growth cycle, forage quality

Developmental characteristics of grass varieties in relation to their herbage production:6. Spring and summer growth of Sabrina hybrid ryegrass and RvP Italian ryegrass as influenced by the date of the initial cut in spring and the length of the succeeding growth period

SUMMARYThe yield and chemical composition of Sabrina hybrid ryegrass and RvP Italian ryegrass were compared, with special reference to regrowth after defoliation in spring and early summer. Initial cuts were taken on 6, 20 April and 4. and 18 May; subsequently a conservation crop was harvested at either 5 or 7 weeks, and a second regrowth 30 days later. There were four fertilizer treatments. Tiller density, stem development and individual tiller dry weight were recorded in selected treatments.At the initial cuts and in the conservation crops after the first three initial cuts, varietal differences in yield and dry-matter digestibility (DMD) were relatively small. In all other harvests, RvP was appreciably higher yielding than Sabrina, and it showed greater responses to fertilizer in all second regrowth harvests. The water-soluble carbohydrate (WSC) content of RvP was consistently higher than that of Sabrina in regrowth harvests; the DMD was higher in Sabrina.In primary growth of the two cultivars, tillering was suppressed at the time of head emergence, but active tillering was resumed earlier in RvP, the later-heading cultivar. In RvP, tillers arising early in the regrowth periods attained head emergence within 5 weeks. In Sabrina there was a marked decline in head production during June, and an increase in the size of individual vegetative tillers.In regrowth harvests both the yield and the % WSC were markedly reduced when drought conditions were most severe; the most marked varietal differences occurred at this time, both in terms of yield of dry matter and % crude protein responses to fertilizer treatment.In the two cultivars the DMD of 7-week conservation crops harvested in late May was at least equal to that of 5-week crops harvested later during drought conditions. A distinctly more advanced stage of development was attained in the earlier, heavieryielding crops.

Cancellation of the Infrared Singularity through the Unitarity Relation

It is shown that the infrared singularities (both soft and collinear divergences) in usual field theories including QCD are cancelled among topologically equal double cut diagrams by appropriate summation over initial and/or final cuts. The basic tools of the analysis are the largest time equation and the power counting method in the space consisting of time plus three momentum components.

Updating Comments On “Paleo-Indian Bison Procurement And Butchering Patterns On The Llano Est Acado”

The 1974 Plains Conference symposium on bison procurement and utilization and subse quent 1978 publication (Davis and Wilson, 1978) represent a major archaeological contri bution towards the interrelationships of cultural adaptation, game animals, and envi ronment. One of the symposium papers (Johnson 1974) represented the author's first, early attempts at bringing together a wealth of butchering data into a cohesive statement and interpretive view. Exchanges during the symposium helped clarify and modify the published version (Johnson 1978). Since that time, further research and experimental work has refined the author's view. Updating comments are in order on three aspects of the paper: processing points, bone butchering (expediency) tools, and group social organi zation. In the initial attempt at a regional butchering pattern (Johnson 1978), proces sing points at pelvic and pectoral girdles (processing beginning down the leg) or at metapodials (processing beginning up the leg) were presented. Butchering experience has modified this view to a selection of effective and efficient butchering units that were stripped after disassociation from* the carcass. Units formed were the skull, two forequarters (pectoral girdle), two hindquarters (pelvic girdle), thoracic region, and lumbar region. The spinal column at times was split into three parts, the cervical region forming another butchering unit. Within the pectoral girdle, the scapula and large shoulder muscles formed a part of the front leg unit. Initial cuts, blows, and slipping of a hand or bone butchering (expediency) tool around and under the scapular area freed the unit. Bone disjointing at this point is unnecessary. Similar action, but more time consuming, occurred with the pelvic griddle. Filleting the innominate around the femoral joint exposed the head and binding ligaments. Disjointing freed the hind leg unit. Leg unit processing modification arose when metapodials were selected for butcher ing (expediency) tools. After skinning but before leg unit removal, metapodials were stripped of tendons, disjointed from the unit, and made into tools. Unit removal butchering would then proceed with aid of these tools. Defleshing cut lines along metapodial anterior shafts were the probable result of tendon removal. During experimentation, cut lines on lateral and medial sides at proximal ends of metapodials resulted from periosteal removal prior to controlled breakage. Periosteal removal may explain cut lines that appear in similar places, such as at the metatarsal tuberosity, on Lubbock Lake metapodials. Wheat (1979:63, 66) notes similar cut line placement on proximal ends of metapodials from Jurgens, many of which had been used as tools or were the debris left from manufacture. Bone butchering tools are a recently recog nized phenomenon. Early attempts at recog nition processes label them unstylized (Frison 1970; Johnson 1975) or simply bone tools (Greiser 1977; Johnson 1978). Assemblages across the Plains (Frison 1977; Greiser 1977; Johnson 1977; Wheat 1977) now demonstrate that specific technological procedures were employed producing a limited variety of results. Interpretive potential is developing as experimentation proceeds and other assem blages are analyzed (Frison 1974, 1978; Wheat 1979; Bonnichsen in press). The expediency concept now applied to these tools (Johnson 1976, 1977) is defined within a technological, not functional, frame work. Expediency tools were made quickly

Structural changes in simian virus 40 chromatin as probed by restriction endonucleases

The structure of simian virus 40 (SV40) chromatin was probed by treatment with single- and multiple-site bacterial restriction endonucleases. Approximately the same fraction of the chromatin DNA was cleaved by each of three different single-site endonucleases, indicating that the nucleosomes do not have unique positions with regard to specific nucleotide sequences within the population of chromatin molecules. However, the extent of digestion was found to be strongly influenced by salt concentration. At 100 mM NaCl-5 mM MgCl2, only about 20% of the simian virus 40 (SV40) DNA I in chromatin was converted to linear SV40 DNA III. In contrast, at lower concentrations of NaCl (0.05 or 0.01 M), an additional 20 to 30% of the DNA was cleaved. These results suggest that at 100 mM NaCl only the DNA between nucleosomes was accessible to the restriction enzymes, whereas at the lower salt concentrations, DNA within the nucleosome regions became available for cleavage. Surprisingly, when SV40 chromatin was digested with multiple-site restriction enzymes, less than 2% of the DNA was digested to limit digest fragment, whereas only a small fraction (9 to 15%) received two or more cuts. Instead, the principal digest fragment was full-length linear SV40 DNA III. The failure to generate limit digest fragments was not a consequence of reduced enzyme activity in the reaction mixtures or of histone exchange. When the position of the principal cleavage site was mapped after HpaI digestion, it was found that this site was not unique. Nevertheless, all sites wree not cleaved with equal probability. An additional finding was that SV40 chromatin containing nicked-circular DNA II produced by random nicking of DNA I was also resistant to digestion by restriction enzymes. These results suggest that the initial cut which causes relaxation of topological constraint in SV40 chromatin DNA imparts resistance to further digestion by restriction enzymes. We propose that this may be accomplished by either "winding" of the internucleosomal DNA into the body of the nucleosome, or as suggested by others, by successive right-hand rotation of nucleosomes.

Staphylococcal nuclease makes a single non-random cut in the simian virus 40 viral minichromosome

When compact simian virus 40 (SV40) minichromosomes are treated with staphylococcal nuclease at 0 °C under limit-digest conditions, about one-third of the minichromosomes remain resistant to nuclease, a third of them are nicked, while the remaining third suffer one and only one double-stranded cut. Results show that each cleaved minichromosome is cut only once and afterwards becomes resistant to further fragmentation. This is in marked contrast to the action of staphylococcal nuclease at 37 °C, which leads to a rapid fragmentation of all minichromosomes to oligo- and mononucleosomes. The SV40 linear DNA III produced by low-temperature nuclease digestion of minichromosomes was redigested with single-cut restriction endonucleases. By this mapping procedure it was determined that the location of the staphylococcal nuclease cut is neither unique nor random; it occurs at a number of discrete sites on the DNA, half of all cuts being concentrated at the origin of replication and nearby in the “late” portion of the SV40 genome. Control experiments have shown that when staphylococcal nuclease digests naked SV40 DNA at 0 °C it does not “hesitate” after the first cut. Although initial cuts in the purified DNA are non-random in location, their distribution is quite different from that generated by a low-temperature nuclease digestion of compact SV40 minichromosomes. Possible interpretations of these results are discussed in view of the recent finding that a specific region of the SV40 genome is uniquely exposed in the minichromosome (Varshavsky et al., 1978, 1979; Scott & Wigmore, 1978).

Dynamic process-response model of river channel development

Feedback mechanisms, which operate upstream through drawdown and backwater effects and downstream through sediment discharge are responsible for channel evolution. By combining these mechanisms with channel processes it euables a dynamic process-response model to be developed to simulate the initial evolution of straight gravel-bed channels. When erosion commences on a land surface, sediment entrained in the headwater reach by hydraulic action is selectively transported, deposited and reworked. This produces a damped oscillation between degradation and aggradation as the channel and valley respond to spatial and temporal variations in sediment calibre and hydraulic conditions. The initial cut and fill phases are responsible for valley incision and floodplain development while secondary and subsequent activity can produce river terraces. Eventually sediment entrainment in the headwaters declines as slopes are reduced. Subsequent channel evolution is relatively insignificant because it is dependent on local weathering activity producing material that can be transported on declining slopes. Therefore landforms produced during the initial phase of development, when local weathering was non-limiting, dominate the landscape.

Influence of cutting date and frequency on dry matter production and nitrogen content of autumn-sown greenfeeds

Abstract The dry matter production of autumn-sown ‘Amuri’ oats, ‘Raven’ wheat, and ‘Grasslands Tama’ ryegrass grown to the milky-ripe stage of grain development before cutting was compared with yields from either 2 or 2–6 cuts made during growth. Nitrogen content was determined in initial-cut herbage at intervals during growth and in the 6-cut regrowth herbage. Delaying the initial cut from May or July through to December increased dry matter production. However, nitrogen content declined from about 4–5% in July–August to less than 1% in November–December. Compared with a single cut in December oat and wheat yields were steadily reduced by increasing the number from 2 to 5 or 6 and Tama yields were similarly reduced up to 4 cuts. The pattern was similar to oats grazed by sheep. Total regrowth yields of Tama ryegrass exceeded those of oats which exceeded those of wheat. Oats and wheat failed to regrow when the initial cut was made after September when sown in March, and after October when sown in April. Tama failed to regrow if the initial cut was made after October. Nitrogen content of regrowth herbage was high (c. 3.5%) from August to November but decreased to about 2.3% in December.

An illumination system for specimen block knife alignment with the LKB ultrotome ultramicrotome

SUMMARYThe principle of using reflected light to align knife to specimen block proposed by Gorycki (1965) is applied to the LKB ultrotome. A small mirror mounted on the knife holder base at an angle of 5° reflects light from the fluorescent lamp on to the front of the knife from where it is reflected on to the block face. The width of this band of reflected light at the bottom edge of the block is reduced as the knife approaches the block. At the point at which it is no longer visible the block is 2–3 μm from the knife. When the knife is parallel with the block in the cutting plane the line of reflection is parallel with the knife edge. Using reflected light facilitates alignment between block and knife and makes closing the gap prior to the initial cut a simple and certain operation.

Regrowth characteristics of an S. 23 perennial ryegrass sward defoliated at early stages of reproductive development

SummaryPatterns of stem development in late spring/summer regrowths after initial cuts at three growth stages are described. The stages at which the initial cuts were taken were: (a) before stem apices were raised to defoliation level (5 cm), (b) two weeks later when the apices of about 90% of the stem tillers were raised above this height, and (c) four weeks after (a), when the apices of all stem tillers were raised well above cutting height.Following an initial cut at stage (a) stem development was quickly resumed, the most advanced tillers being devoid of leaf blades. After initial cuts at the later stages there was virtually no stem development until after the fourth week of regrowth.The greater proportion of stem tillers in the earlier regrowth was not reflected in reduced digestibility during the first six weeks from cutting.Reproductive (apical) development was generally weak in tillers in which stems developed in midsummer (after cutting at stages b and c); at least two-thirds of these tillers were indeterminate.The significance of the distinct batch of stem tillers developing in spring is discussed, and the data are also considered in relation to (i) avoiding stemmy regrowths in spring, (ii) stem development and herbage quality, and (iii) summer stem extension and the perennation of the sward.

Slow crack growth in cellulose film

AbstractA simple photographic method for measuring the slow crack growth in transparent polymer film is described. Framing speeds up to 100 per second have been achieved. Experimental data for a cellulose film with centrally located initial cuts indicate that for 0 < t < 0.8tb, the crack length c increases with time t according to where c0 is the initial cut size, K a constant, and tb the time to fracture.

Some effects of lime and molybdenum on the growth of white clover in autea clay

Abstract Results are reported of the effects of different rates of lime and molybdenum on the yield and composition of white clover grown under glass-house conditions on a molybdenum-deficient strongly leached clay soil of low pH. Molybdenum alone at 1 oz/acre caused a rise in yield, which was greatly increased by lime, but amounts of molybdenum above 1 oz/acre produced no additional effect in the presence of lime, and no consistently significant yield increase in its absence. Lime alone at the 1 ton rate gave yield responses of the same order as molybdenum, and each successive increment of lime gave a further increase. At the 1 ton and 2 ton rates of lime molybdenum gave a further increase, but not at the 4 ton rate. Plant manganese levels ranged from 150-286 p.p.m. in the treatments without lime, but progressively decreased with each increment of lime. The level of manganese associated with adverse effects on growth not corrected by molybdenum was in excess of 100 p.p.m., and this was independent of the Mn:Mo ratio in the tops. High N levels were produced by 4 tons of lime and by lower rates of lime combined with molybdenum, but lower rates of lime without molybdenum gave reduced N levels. Molybdenum alone gave very low N levels in the initial cut, but levels were high in a later cut. Maximum yields were associated with high N levels in the foliage and with Mo levels of 0.1-4.7 p.p.m. Levels of molybdenum of 2 p.p.m. and over were compatible with both low and maximum yields but where yields were low there was evidence that adverse factors associated with high manganese levels were operating. Where these. factors were not operating low Mo levels of 0.4 p.p.m. or less were associated with low yields only when N levels were low.

Computer Processing of Log Data Improves Production In Chaveroo Field

Abstract Computer log analysis has proved quite successful in the Chaveroo field of Roosevelt County, N.M., in a carbonate section of low permeabilities, low porosities and variable water saturations. Production in this field occurs at about 4,300 ft in the San Andres formation, a Permian carbonate with a mixture of dolomite, anhydrite and gypsum, and lesser amounts of silica, limestone and silt. Sonic, density and neutron logs, all of which respond differently to porosity and lithology, enable a mathematical solution that defines the fractions of major lithologic components and gives the correct porosity. The Laterolog and Microlaterolog are used to solve for a movable oil relationship. The computer output is a log of bulk volume percentages of porosity, dolomite, anhydrite, gypsum and silica, and a movable oil plot. The record shows that wells completed on the basis of this computer log analysis statistically have higher initial productions and lower water cuts than wells completed on the basis of less diagnostic logging techniques. Introduction The Chaveroo pool is characterized by conditions generally considered hostile to effective log interpretation. Porosities are low-about 5 percent in most producing intervals. The intervals are predominantly dolomite, but contain unpredictably varying fractions of anhydrite, gypsum, chert, silt and limestone. Formation resistivities are high, and most wells are drilled with salt mud. However, in spite of these difficult conditions, modern logs and interpretation methods are giving information needed for efficient completion in the Chaveroo pool. The more efficient completions are obtained by avoiding water-productive intervals interspersed among the pay section of the pool. The produced water fraction is important in Chaveroo because it usually determines whether a well will flow or will require pumping. Thus, better completions are possible when water-productive intervals are distinguished from pay zones. Logs both define pay sections and identify water-productive intervals. Porosity information from logs is used with resistivity data to define fluid saturations. However, because the lithology is variable, no single log defines porosity with sufficient accuracy to reliably distinguish between pay and water. Sonic, neutron and density logs, all of which respond differently to porosity and lithology, are used in a mathematical solution that identifies major lithologic components and thus affords a reliable value of porosity. Office-based electronic computers are used to perform the mathematical solutions. The output of the computer is a log of percentages of major lithologic components and porosity, and an index of movable oil and water saturation. Statistics show that wells selectively completed on the basis of these computer logs are more efficient producers than other wells of the Chaveroo pool. These wells generally flow with higher initial oil production and produce less water. The logs and interpretation methods presented in this article are not entirely new. Earlier papers have described the primary logs, the basic interpretation methods and typical applications of computers to log studies. This study is presented to show how the various logs and methods are combined for improved well completion in the Chaveroo pool. The methods are not restricted to Chaveroo; they are similarly appropriate for other areas of complex lithology. Chaveroo Field Chaveroo field straddles the line between Chaves and Roosevelt Counties of eastern New Mexico (Fig. 1). Production is from the Slaughter zone of the San Andres formation. The main producing interval is about 650 ft below the top of the San Andres, and is at an approximate depth of 4,150 ft. The Slaughter zone, situated between two massive anhydrite sections, is 200 to 250 ft thick. It is described as a fractured, vuggy dolomite having some intercrystalline and oolitic porosity. In addition to interbedded and nodular anhydrite, the zone also contains variable but lesseramounts of gypsum, chert, silt and limestone. JPT P. 889ˆ

THE PRODUCTIVITY OF INTERMEDIATE WHEATGRASS AS AFFECTED BY INITIAL HARVEST DATES AND RECOVERY PERIODS

The productivity of Agropyron intermedium (Host.) Beauv., as influenced by variation in the date of initial harvest and length of recovery period between cuttings, was studied on irrigated land over a 2-year period. Ten initial cutting dates, each spaced 3 days apart, and two recovery periods of 21 days and 42 days, were used. Delaying the initial harvest date resulted in progressively greater dry-matter yields at the first cutting and progressively lower yields at the second cutting. Earlier and later initial cuttings gave higher yields than at the shotblade stage when this species seems to be in a critical phase of development. Grass given a 42-day recovery period between cuttings produced an average dry-matter yield of 3.63 tons per acre over the 2-year period, and 1.71 tons of root material per acre in the first crop year. Comparable yields in tons per acre for grass given a 21-day recovery period were 2.29 for dry matter and 1.31 for root material. Likewise, grass given a 21-day recovery period showed a rapid stand deterioration, whereas that given a 42-day recovery period did not show a reduction. Intermediate wheatgrass is high-yielding if managed properly and not abused by intensive cutting or grazing. It appears to be more suitable for hay production than for pasture.

Bottom-Water and Edge-Water Effects on Low Gravity Oil Production

Abstract Water encroachment into low gravity oil reservoirs tends to be irregular because of three mechanisms -selective encroachment,water-leg tonguing andindividual well coning. An investigation was made of 31 wells that were completed in low gravity oil sands with bottom water present in the base of the well-sand interval. It was found that initial water cuts occurred rapidly. Current average recovery for each of the 31 original completions is 10,184 bbl (31 per cent) clean oil and 22,542 (69 per cent) wet oil. Fourteen (45 per cent) of the 31 original completions have either been recompleted to other sands or are not feasible to produce because of high water-cut production. Average cumulative recovery for each original completion is now only 32,726 bbl of oil. Four low gravity oil reservoirs with well defined fault boundaries and original oil-water contacts were studied to ascertain the effects of irregular edge-water encroachment. This study showed that initial water cuts have rapidly occurred in all 12 (including the most up-dip) wells completed in the four reservoirs; only two of these wells were completed with an original water-leg extension in the base of the well-sand interval. Comparative clean and wet oil recovery from these four reservoirs has been 419,100 bbl (34 per cent) clean oil vs 810,500 bbl (66 per cent) wet oil. Ultimate recovery from the abandoned MG–30 reservoir is 1.9 per cent of the 8 million STB of oil initially in place. It is concluded that selective encroachment of edge water along thin, highly permeable, stratum has acted to reduce ultimate recoveries in the four reservoirs from 7 per cent - the recovery that would be expected if solution gas drive were the depletion mechanism. Two basic remedial techniques offer a possible solution for eliminating adverse (irregular) edge-water encroachment. One of these is gas pressure maintenance. The second technique embodies the production of water from the more down-dip areas of the reservoir to balance water influx from the associated aquifer.

The attack of ozone on stretched rubber vulcanizates. II. Conditions for cut growth

Experimental measurements are described of the conditions necessary for crack growth in an atmosphere containing ozone. It is proposed that a characteristic value of the tensile stress at the tip of an initial cut or surface flaw is required for growth to occur. This criterion is shown to predict the observed dependence of the applied stress required for crack growth on the length of an initial cut and on the surface smoothness of uncut test pieces. The number of cracks formed in an exposed edge is also shown to be in accordance with the proposed criterion. For vulcanizates of differing stiffness, the appropriate criterion is found to be the stored elastic energy. The critical value is shown to be similar for a number of different polymers, and largely unchanged by plasticization, a change in temperature from 20°C. to 50°C., and alteration in the concentration of ozone. For initial flaws consisting of sharp razor cuts, the energy required for cut propagation is found to be about 60 ergs/cm.2 of newly formed surface.