The Cimarron Bend of southwestern Kansas is characterized by loess, dunes, and sand sheets that reflect a complex eolian–alluvial history. Stratigraphic evidence indicates that at least two major dune and sand sheet reactivation episodes occurred. These follow intervals of alluviation, stability, and soil development in the Holocene. Radiocarbon ages from paleosol horizons bracket these periods and their δ13C values provide evidence of a shift from a cooler, wetter climate in the late Pleistocene and early Holocene dominated by C3 plants, to a warmer, drier middle Holocene period characterized by an increase in C4 plants. Stable isotopic results for late Holocene soils may reflect local rather than regional climatic conditions. Our results compare favorably with studies in the central and southern Great Plains. Together, these results imply that a regional change toward a warmer, drier climate occurred from the early to the middle Holocene on the southern Great Plains.

The purpose of this investigation was to determine the effects of a 12-week progressive resistance-training program (PRT) on single myofiber calcium sensitivity in six older women (73 ± 2 yr.). Muscle biopsies of the vastus lateralis were obtained pre-and-post PRT. Single muscle fibers were dissected and mounted between a lever arm and force transducer in an experimental chamber. The experimental sequence for each fiber was the determination of maximal isometric tension (Po) at pCa 4.5 (pCa = −log[Ca2+]), and then subsequent submaximal activations of the fiber at nine Ca2+ concentrations (pCa 6.8 to 4.7). MHC I and IIa fiber diameter increased 16% (p < 0.05) and 2% pre-to-post PRT, respectively. Peak isometric tension in MHC I and IIa fibers increased 34% (p < 0.05) and 18% as a result of the training. The mean MHC I Ca2+ activation threshold increased from 6.83 ± 0.02 to 6.91 ± 0.01 (p < 0.05) as did the mean half-maximal activation 5.51 ± 0.02 to 5.71 ± 0.03 (p < 0.05) with PRT. The slope of the Hill plot above (n1) half-maximal activation for MHC I did not change significantly with the PRT (1.80 ± 0.04 to 1.86 ± 0.08). However, the slope of the Hill plot below (n2) half-maximal activation for MHC I demonstrated an increase (p < 0.05) with training (1.70 ± 0.11 to 2.43 ± 0.09). There were no differences with MHC IIa fibers with PRT for any of the Ca2+ variables measured. In conclusion, the results of this investigation indicate that myofibril ca2+ sensitivity and activation properties are altered in MHC I, but not MHC IIa fibers with PRT in older women. The alterations in the MHC I Ca2+ properties appear to have a significant effect on the mechanisms involved with skeletal muscle adaptability in older women following PRT. Supported by NIH AG154876

1769 The intent of this investigation was to examine the quantitative alterations in neuromuscular drive (Electromyography) during submaximal and maximal intensities, as well as changes in cross sectional area (CSA) and functional ability during a 12-week bilateral knee extensor resistance training program (RTP). The RTP consisted of 2 sets of 10 repetitions, and a third set to volitional exhaustion at 80% 1RM, 3 days/week for 12 weeks. Ten healthy men (70.8±1.5yrs, 80.28±3.6kg, 174.5±2.1 cm) were evaluated for submaximal and maximal isometric electromyography (EMG), bilateral 1-repitition maximum (1RM), and whole muscle CSA of the right mid-thigh by computed tomography (CT), pre-and-post RTP. Isometric EMG of the v. lat and v. med was performed at 27 N·m and 55 N·m workloads, at 30°-knee extension. 1RM strength and CSA increased pre-to-post-training 57±5% and 7±1%, respectively. Submaximal EMG (expressed as a % of MVC EMG) for the v. med. and v. lat. decreased 35±7% and a 12±7% at 27 N·m and 36±7% and 27±8% at 55 N·m, respectively. The post-training maximal isometric EMG increased 58±26% for the v. med. and 30±5% for the v. lat. All data above are statistically significant (p<0.05), with the exception of the submaximal EMG v. lat. at 27 N·m. Torque/EMG was similar in v. med. (11±9% Δ) and v. lat. (5±5% Δ). A comparison of torque/CSA revealed a 14±3% increase pre-to-post training (p>0.05). In conclusion, the training increased 1RM strength, CSA, maximal EMG, while submaximal EMG decreased. In addition, the commensurable changes of torque with EMG and CSA suggest that hypertrophy and neural drive did not account for all of the increases in muscle strength. Supported by NIH grant AG154876

1273 HISTORY - A 19-year-old freshman Division I hurdler noticed a gradual onset of right medial foot pain. There was no specific injury. The pain worsened with increasing intensity and duration of practice, and was mildly relieved by rest. She was initially treated for posterior tibial tendinitis. Treatments included strengthening exercises, ultrasound, and anti-inflammatories. However, she continued to have continued pain. PHYSICAL EXAMINATION - Examination in the training room revealed vague midfoot pain. The posterior tibial tendon appeared to be intact. There was minimal to no pain over the deltoid ligament. There was no midfoot collapse. She could do a good toe raise, but had mild pain. Her ankle was stable to anterior drawer and talar tilt. There was minimal pain at the Lis franc area, and worsening pain just lateral to the anterior tibial tendon. DIFFERENTIAL DIAGNOSIS: Posterior tibial tendinitis Midfoot sprain Anteromedial ankle impingement Navicular stress fracture Spring ligament rupture TEST AND RESULTS: Plain x-rays: normal Lis franc joint, no collapse of the midfoot slightly increased sclerosis of the navicular, no definite stress fracture Bone scan: - intense uptake in the right foot with no uptake in the left foot CT scan of the midfoot: incomplete navicular stress fracture no disruption of the Lis franc joint, no spurring within the ankle joint FINAL/WORKING DIAGNOSIS: Right incomplete navicular stress fracture. TREATMENT: 6 weeks of immobilization with a cast and crutches without resolution of symptoms. ORIF of a right navicular stress fracture with a distal tibial onlay bone graft. Fracture walking boot at 6 weeks, custom orthotic at 3 months. Running at 5 months, sprint training at 6 months. Currently participating in Division I track without symptoms.

The uppermost surficial stratigraphic unit south of the Arkansas River in the Kansas High Plains is a previously unidentified middle Holocene or younger loess. The unit fits both a loess-thickness and a particle- size model for loess distribution with increasing distance from source. A soil immediately below this unit is radiocarbon dated 6000 to 6700 years BP. The radiocarbon ages indicate that the loess unit is younger than the commonly reported ranges for Bignell Loess in the Great Plains and demonstrate a need for re-examining Holocene loess stratigraphy of the Great Plains. In some locations closest to the Arkansas valley source, this middle Holocene unit is overlain by, or interfingers with, dune sands. The presence of these aeolian sands indicates that, following a period of relative landscape stability and soil development, a shift toward a middle- Holocene climate in which aeolian processes dominated occurred about 6000 years ago on the High Plains of west-central Kansas.

HISTORY - A 20-year-old Division 1 pole vaulter suffered medial foot and ankle pain when he landed off of the mat and hit the pole vaulting standard after vaulting 18 feet. He had acute onset of pain with an impact loading to the left medial ankle. Examination at that time revealed ecchymosis and swelling localized about the left medial heel and on the medial aspect of the foot. Plain x-rays at that time were thought to be negative. He was treated for a medial ankle sprain. He attempted to go back and do cross training but had a great deal of difficulty running and had difficulty getting up on his toes. He had continued swelling in the area of the medial heel and midfoot. X-rays of the foot at that time again were negative. At two months the patient was still unable to resume walking activities comfortably. He was unable to participate in any running or sprinting activities and his pain was more localized to the medial midfoot and arch area. PHYSICAL EXAMINATION - Examination 2 months showed residual fullness localized about the midfoot with a normal range of motion of the ankle subtalar midfoot and forefoot. There was good strength throughout the tendinous structures of the foot and pain was localized to the medial midfoot. He was unable to walk on his toes and had pain with single heel raise. DIFFERENTIAL DIAGNOSIS: Medial ankle sprain with deltoid ligament injury Posterior tibial tendon tear Talo-navicular and spring ligament complex injury Lis franc ligament injury TEST AND RESULTS: Standing x-ray examination of left foot: approx 6 mm subluxation of tarsal navicular joint with dorsal subluxation of navicular on talus MRI examination of left foot: diffuse edema pattern with mild flattening and peripheral fractures of minimally subluxed left navicular complete rupture of left spring ligament with anterior deltoid ligament injury. FINAL/WORKING DIAGNOSIS: Spring ligament complete rupture with acquired flat foot and anterior deltoid ligament tear. TREATMENT: 1. Surgical repair of spring and anterior deltoid ligament. 2. 2 weeks - ROM exercises with plantar flexion and inversion. 3. 6 weeks - cast brace, PWB. Progressed to FWB by 8 weeks. 4. 12 weeks - jogging with shoe orthosis. Jumping - 6 months. 6. 9 months - unrestricted activities. Set American record 18 months after surgery. Won USA Olympic trials in 1996.

Summary This paper describes a one-step fracturing/gravel-pack (frac-and-pack) completion procedure conducted on the BP Exploration Amberjack platform beginning in early 1992. This platform is 35 miles southwest of Venice, LA. The first four completions on this platform had an average positive skin values of 21. The goal of the frac-and-pack procedure was to reduce these skins to nearly zero. In total, 24 frac-and-pack operations were performed. Details of the fracture design, prefracture testing, fracture design and execution, and production response and a continuing optimization program are discussed. The fractures were performed with the screens in place with the gravel pack after the fracturing operation. The treatments were designed for the tip screenout technique1,2 to create wide fractures and to provide proppant loadings exceeding 8 lbm/ft2. This paper presents the trend of the declining skin values, along with a discussion of time-dependent skins. The changes in fluids, breakers, and proppants are also presented. The average skin on 14 frac-and-pack completions was 5.3. The average skin on the final eight completions was 0.2.

INTRODUCTION Maximizing profits is the ultimate business objective in all drilling and completion operations. By far and away the biggest contributor to profits is the productivity of the well. Reliability and costs certainly impact profits; however, they pale in comparison to productivity when a rigorous calculation of net present value is performed. The simplest and most effective way to improve productivity is to increase the quantity of net reservoir exposed to the wellbore. A horizontal trajectory is the ultimate way to maximize the length of formation exposed to the wellbore. Drilling and completion technology development over the last several years has made the use of horizontal wellbores in unconsolidated formations practical. Utilizing a unique mixture of new and existing technology, BP recently brought their first horizontal well in the Gulf of Mexico on line in record setting fashion. The planning, installation and results of this team effort are detailed in this operations oriented paper. GEOLOGY AND RESERVOIR The majority of the reserves in the Amberjack (Mississippi Canyon 109) field are contained in the "Green or G-sand", a very unconsolidated Pliocene reservoir. Permeability of the reservoir ranges from 300 to 1000 md with the pay zone varying from clean to laminated sand/silt/shale. The G-sand was targeted for this horizontal wellbore with a projected thickness of 40' tvd based on 3D seismic data and offset well logs. The G-sand reservoir was deposited by a shelf-edge delta system which laid down the sediments as a series of shingled mouth bar sands separated by dipping silt beds. These depositional units are referred to as "clinoforms" (refer to Figure 1). Barriers to flow of reservoir fluids between these packages of sand and silt were predicted from 3D seismic data and well logs. The potential for reservoir compartmentalization in this type of stratigraphy was the major consideration for proposing the A-5 horizontal wellbore. Significant differences in oil properties and water contacts in several wells drilled to date indicated that isolation of some areas was likely. While not all clinoform boundaries are sealing, the challenge for field development has been to ensure effective recovery with a minimum number of wells. The A-5 well was oriented to use a single horizontal wellbore to drain three clinoforms in the western portion of the field and planned to take the place of two or three conventional wellbores. The wellbore was oriented perpendicularly to the clinoform depositional axes with the completion interval draining all three packages (Figure 2). A secondary benefit of the A-5 was to reduce the tendency for bottom-water production by providing additional standoff from the oil-water contact in the relatively thin oil column in the target region. Previously drilled conventional wells have typically produced water within 6 months of completion through either water coning or overrunning mechanisms. Reservoir simulation was carried out to evaluate potential benefits of the non-conventional well and to evaluate sensitivities to reservoir description uncertainties. A cross-sectional model was used to investigate reservoir description issues including kV/kh ratio, bedding plane orientation, and clinoform boundary transmissibilities.