No abstract

Twenty-eight Holstein-Friesian heifers, born the previous year and weighing between 130 and 310 kg, were allocated to one of two treatment groups by restricted randomisation, based on their initial weight. The heifers in group 1 were each treated with ivermectin in a sustained-release bolus formulation at turnout in April, and those in group 2 were each given an ivermectin bolus on July 10, 84 days after turnout. On that day the mean geometric worm egg counts of groups 1 and 2 were 0.4/g and 38.8/g, respectively, and they both had a mean plasma pepsinogen concentration of 0.59 iu/litre; in group 1, two of 14 faecal samples were positive for Dictyocaulus viviparus larvae, and in group 2 all 13 samples were positive; in group 1 eight calves were positive and three inconclusive for the presence of antibodies to D viviparus, and in group 2 the corresponding figures were 10 positive and two inconclusive; the mean liveweights of groups 1 and 2 were 274.4 kg and 262.8 kg, respectively. By December 4,231 days after turnout, the corresponding results were: mean geometric worm egg counts of 2.2/g and 0.5/g; one of 13 and none of 14 faecal samples positive for D viviparus larvae; 12 positive and two inconclusive and none positive and 10 inconclusive for the presence of antibodies to D viviparus; 214 days after turnout their mean liveweights were 361.1 kg and 358.3 kg. Although the patterns of parasitic nematode infection were different in the two groups during the grazing season, by the time they were housed both groups had achieved similar liveweights and showed evidence of an immune response to both D viviparus and gastrointestinal nematodes.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe Jotun Field is located approximately 165 kilometers offshore Norway in 127 meters of water. Jotun development drilling was executed from a wellhead platform with a fit for purpose new build drilling rig.

The relationship between lice infestation in calves during their first winter and damage to the leather produced was investigated in a trial involving 500 calves, 100 of which were treated with a pour-on endectocide during the first winter. All the calves received routine lice treatment in the second winter and were reared to slaughter weight. The hides were removed at the abattoir, tanned, inspected for lice-related damage, and graded according to their suitability for the production of high quality leather. The untreated group developed natural infestations of the chewing louse (Bovicola bovis) during the first winter but none was observed in the second winter. Hides from cattle infested with lice in their first winter had higher levels of lice damage than hides from those treated with eprinomectin, at both the chrome-tanned and dried dyed-crust stages of leather production.

The Jotun Field is located approximately 165 kilometers offshore Norway in 127 meters of water. Jotun development drilling was executed from a wellhead platform with a fit for purpose new build drilling rig. All production wells were planned as complex directional, horizontal producers in Paleocene, Heimdal sandstones at a depth of approximately 2050 meters TVD SS. Reservoir target complexity dictated tortuous directional well paths often resulting in azimuth changes in excess of 90 degrees at high angle, horizontal inclinations. Target tolerance ±1m was common place at measured depths out to 6000 meters. Directional control and well tortuousity were critical well design considerations. An agreement was reached between Esso Norge AS and Baker Hughes Inteq to utilise AutoTrak™ steering technology on all 12 1/4 inch intermediate and 8 1/2 inch horizontal hole sections on the Jotun B Platform. Drilling commenced in April 1999. This was the first field to be developed using rotary steering technology. To date, 1 water injection well and 14 horizontal production wells have been drilled on Jotun B. This paper provides a history of drilling performance utilising rotary steerable technology on the Jotun B Platform. The following topics are discussed:Well design considerations and complex 3- dimensional well pathsDrilling performanceAutoTrak™ tool performance and reliabilityRotary steering hole conditioning benefits Introduction Directional drilling is necessary to allow wellbores to be optimally placed to meet reservoir access objectives. The amount of directional drilling required has a significant impact on the drilling rate of penetration (ROP) that can be achieved over a hole section. Conventional directional drilling techniques do not allow the drill string to be rotated while the well path is being oriented. The drill string must slide in the wellbore until the desired direction and/or inclination is achieved. New rotary steerable technologies allow the drill string to be rotated while the wellbore is being directionally drilled. The ability to directionally drill while rotating the drill string greatly improves the effective penetration rate, particularly on longer extended reach wells where friction between the wellbore and drill string makes sliding difficult. Rotary steerable technologies are available from several service suppliers. All of the technologies provide the capability to rotate and directionally drill, thereby increasing effective penetration rate. The decision to utilize a rotary steerable system for the Jotun development was based on achieving a lower cost well through reduced drilling times. Drilling Objectives A total of 15 wells were drilled as a part of the Jotun development. Fourteen horizontal oil producers and one water injector. All fourteen of the oil producers were drilled to access oil reserves in the Heimdal reservoir. All wells were drilled from the Jotun wellhead platform with oil production to a Floating Production Storage and Off-loading facility. The Jotun B platform was positioned to be able to access each of the three Jotun reservoirs within a horizontal distance of 6000 meters. To be able to place each of the horizontal wellbore sections in the reservoirs at the required orientations, complex three dimensional well paths were required. Achieving the specified orientation was critical to minimizing the number of wells needed for reservoir drainage (Fig. 1).