Tall fescue (Festuca arundinacea Schreb.) is widely grown as a winter perennial forage in the upper South. It is primarily used for cool‐season grazing by cattle producers, and improved digestibility and increased fall and winter forage production would be useful. A field experiment was conducted for 3 years on a tall fescue sod growing on a member of fine loamy mixed family of Cumulic Haplumbrepts to establish the effect of four clipping schedules, 5‐ and 10‐cm clipping heights and 56‐ and 224‐kg/ha N‐rates on dry forage yields, tiller numbers, and percent invaders. Forage yields varied from slightly more than 3,600 kg/ha when fertilized with 56 kg/ha of N and clipped at a height of 10 cm to more than 8,820 kg/ha when fertilized with 224 kg/ha N and clipped at 5 cm. Reducing the clipping height from 10 to 5 cm increased average forage yield from 5,512 to 6,735 kg/ha or 22%. Increasing N fertilization from 56 to 224 kg/ha doubled dry forage production from 4,137 to 8,111 kg/ha. Tillers/unit area were highest at the 5‐cm clipping height, 224 kg/ha rate, and frequent clipping schedule. Lowest numbers of tillers/area were obtained on plots clipped at 10 cm, fertilized with 56 kg/ha N, and clipped infrequently. Invaders were limited almost exclusively to plots clipped at a height of 5 cm where 56 kg/ha N was applied. Very few invaders were present on plots clipped at 10 cm. More invaders were present on 56‐kg/ha N plots than on 224‐kg/ha N plots. Tall fescue responded to management treatments applied. However, it is probable that new treatments can be developed that will more uniformly distribute forage production through the season, facilitate the introduction of invaders (clovers), and stabilize tillers/area for increased fall and winter growth and improve forage quality (digestibility). These additions would add appreciably to the value of tall fescue as a forage crop in the Southeast.

Despite two decades of use of nitrogen fertilizer to grass pastures, the rising cost of N and the introduction of new legumes and cultivars is cause for a reappraisal of grass‐legume mixtures for pastures in the South. The objective of this study was to evaluate new legume species and cultivars under two simulated grazing pressures. Information on production and clipping tolerance of these new legumes and cultivars is needed to plan management for production and persistence. In the fall of 1970 tall fescue cultivar ‘Ky 31’ (Festuca arundinacea Schreb.) was seeded alone or with each of 10 legumes. During the summer of 1971 and 1972 plots were harvested monthly at heights of 5 and 10 cm. In 1973 only four harvests were made as compared to six for each of the first 2 years. Milkvetch (Astragalus cicer, L.) failed to persist in association with fescue and produced little more than fescue alone. Red clover (Trifolium pratense L.), produced high yields but persistence was short. Crownvetch (Coronilla varia L.), birdsfoot trefoil (Lotus corniculatus L.), and white clover (Trifolium repens L.) persisted well and significantly increased forage yields. The newer cultivars tended to be significantly higher yielding than the old ones. The crownvetches, red and white clovers, and birdsfoot trefoils were tolerant to heavy defoliation and increased forage yields. The use of these legumes in forage programs appeared to be highly desirable.

In the last two years much progress has been achieved in the fie/d of horizonta/ dri//ing in unconsolidated reservoirs. Horizontal completions have become a common, successful, and economical method to produce unconsolidated reservoirs. This paper outlines the techniques used to drill and complete seven horizontal wells in the Gulf of Mexico over the last two year period. All of the wells are currently producing at or near the anticipated productivity levels and all have produced at rates considerably higher than vertical offsets. The wells were drilled using a concept that linked the drilling and completion phases together to streamline the total operation and minimize the potentia/ for formation damage. The concept is based on the premise that the drilling stage should not cause any damage that cannot be removed in the completion stage. This allows the well to be completed as an open hole and greatly simplifies the procedures involved.The procedures which were used do not require the wells to be cased, or perforated and the only sand control which has been implemented is a mechanical screen across the open hole intetval. The wells were drilled with a fluid containing solid sized salt particle bridging agents and a series of clean-up procedures that Drovide a vetv economical completion. This paper describe; the guidelines that were used on the completions and also elaborates on the problems which were encountered to allow knowledge to be gained from the concerns which have been addressed by these pro]ects.

A new reservoir drilling fluid system utilizes a non-biopolymer, acid- or enzyme-soluble polymer that serves both as viscosifier and fluid-loss additive when combined with activated magnesium oxide and a divalent-cation-based brine. The new fluid shows a unique shear-thinning rheological profile featuring relatively low, high-shear-rate viscosity along with relatively high, low-shear-rate viscosity. This behavior is highly unusual in high-density, brine-based reservoir drilling fluids. A result of this behavior is that effective hole cleaning is provided without generating excessive high-shear-rate viscosities that lead to disproportionate equivalent circulating densities. The new fluid system is based on the higher density, divalent-cation-containing brines (utilizing CaCl2, CaBr2, CaCl2 / CaBr2, ZnBr2 / CaBr2 and ZnBr2 / CaBr2 / CaCl2) in the 11.5 to 17.5 lb/gal density range. The total amount of the sized CaCO3 bridging particles is kept relatively low, 13 to 35 lb/bbl, so that thin, chemically removable filter cakes are produced. The size distribution of these bridging particles is designed according to the ideal packing sequence for optimizing sealing and producing a minimally invading (well productivity enhancing) fluid. Introduction A number of technical advances in the petroleum industry have created cost-effective methods for the exploration and development of deep oil and gas reservoirs. One result of these developments is an increased demand for higher density reservoir drilling fluids (RDF's). However, the density attainable for economically viable, brine-based reservoir drilling fluids is limited under current technology.1,2,3,4 Some limitations are based on the fact that current biopolymer-CaCO3-brine-based reservoir drill-in fluids utilize viscosifiers that are either incompatible with the higher-density brines or require special mixing equipment / techniques and complex formulations.1,2 In other cases, the cost of a base brine compatible with currently available biopolymer viscosifiers is such that the final drill-in fluid is priced out of consideration.4,5 This paper presents a newly developed biopolymer-free fluid system that uses conventional high-density base brines to fulfill the density requirement, a low concentration of bridging-solids, and a new viscosifier / fluid-loss package to produce an easily blended drill-in fluid with exceptional rheological and filter cake qualities. Most brine-based reservoir drilling fluid systems used today consist of five primary components: base brine, pH control additive, biopolymer-derived viscosifier, starch-based fluid-loss additive, and bridging particles.5,6 Containing no biopolymers, such as xanthan7,8 gum or scleroglucan,9 the new non-biopolymer reservoir drilling fluid (NBRDF) system uses a single acid- or enzyme-soluble starch that fulfills the role of both viscosifier and fluid-loss additive when combined with a divalent-cation-based brine and a highly activated magnesium oxide. This fluid delivers a unique shear-thinning rheological profile that provides effective hole-cleaning without generating excessive high-shear-rate viscosities that lead to disproportionate equivalent circulating densities.10,11 The new fluid system is based on the higher density, divalent-cation-containing brines in the 11.5 lb/gal to 17.5 lb/gal density range. Brine-based fluids based on calcium chloride, calcium bromide, and zinc bromide brines provide several advantages. Formulating RDF systems in heavier brines minimizes the solids concentration required to weight-up to a high density. Keeping the solids low results in a lowering of the plastic viscosity. Buoyancy, or the upward pressure exerted by a fluid against particulates in the fluid, reduces the demands upon the viscosifying additives for particle suspension and cuttings removal.

Low-solids, brine-based reservoir drilling fluids (RDFs) are widely accepted as beneficial to optimizing compatibility with the completion design while minimizing fluid-related formation damage. Traditionally, the maximum density attainable with a lowsolids fluid has been limited because of either the prohibitively high cost of the required base brine or the poor performance of viscosifying biopolymers in a dense, divalent cationic environment.An RDF has been developed that exhibits unusually high quality rheological behavior in high-density calcium-and zinc-based brines without the aid of a biopolymer. The new fluid shows a unique shear-thinning rheological profile that features a relatively low high-shear-rate viscosity along with a relatively high lowshear-rate viscosity (LSRV). This behavior is highly unusual in high-density, brine-based RDFs. A result of this behavior is that effective hole cleaning is provided without generating excessive high-shear-rate viscosities that lead to excessive equivalent circulating densities (ECDs).The first field trial of this fluid was on the reservoir section of Well 34/10 I-1-AH in the Gulfaks Satellites Development in the Norwegian sector of the North Sea. Fluid properties during pretesting, mixing, drilling, and completion of this section are detailed in this paper.