Methods of administering propylene glycol to reduce plasma nonesterified fatty acids (NEFA) during feed restriction of cattle were evaluated. Treatments were 1) no propylene glycol supplementation, 2) propylene glycol provided as an oral drench once per day, 3) propylene glycol mixed with concentrate and fed separately from forage, or 4) propylene glycol blended as part of the total mixed ration (TMR). Prior to or during feed restriction at 50% of ad libitum intake, propylene glycol was provided once daily at 2.5 ml/kg of body weight. Prior to feed restriction, administration of propylene glycol as an oral drench or mixed with concentrate was more effective in increasing serum insulin than was feeding propylene glycol as part of the TMR. During feed restriction, administration of propylene glycol as an oral drench or mixed with concentrate resulted in higher serum insulin and lower plasma NEFA concentrations than did feeding propylene glycol as part of the TMR. Propylene glycol decreased the molar percentage of ruminal acetate and the ratio of acetate to propionate. Propylene glycol administered as an oral drench or mixed with concentrate and fed separately from forage appeared to be more effective than feeding propylene glycol as part of the TMR for influencing plasma NEFA in cattle during feed restriction.

It was hypothesized that a high dose of estrogen in conjunction with a long-acting PGF2 alpha analog would synchronize parturition within a narrow time frame and reduce the incidence of retained placenta. On d 276 of gestation, 14 animals (9 cows and 5 heifers) per group received a placebo (group A), 1 mg of fenprostalene (group B), 50 mg of estradiol-17 beta benzoate (group C), or both (group D). Treatment with estradiol-17 beta benzoate increased serum concentrations of estradiol-17 beta from 228 pg/ml at treatment to 642 and 683 pg/ml at 24 h posttreatment for groups C and D, respectively. Concentration of estradiol-17 beta in group A increased gradually to 526 pg/ml at 24 h prepartum. Progesterone concentrations were reduced by fenprostalene but not by estradiol-17 beta benzoate. Estradiol-17 beta benzoate did not reduce incidence of retained placenta in animals treated with fenprostalene (group B vs. group D) but tended to reduce incidence in uninduced animals (group A vs. group C). Thus, short-term elevation of estradiol-17 beta to normal prepartum concentrations did not regress the corpus luteum, induce parturition, or reduce incidence of retained placenta. However, elevation of estradiol-17 beta for longer periods might enhance placental separation. Conversely, fenprostalene induced calving approximately 2 d after treatment. In this study, 90% of animals treated with fenprostalene calved within a 20-h period, but with a high incidence of retained placenta.

The effect of induced parturition and estradiol on feed intake, liver triglyceride, plasma metabolites, and milk yield was evaluated in fifty-six Holstein cows and heifers. Cows were assigned to treatments on d 260 of gestation and were on trial until d 10 postpartum for measurement of dry matter intake (DMI), plasma metabolites, and liver triglyceride and until d 31 postpartum to measure milk yield. Fourteen animals per group (9 cows and 5 heifers) received either a placebo, 1 mg of fenprostalene, 50 mg of estradiol-17 beta benzoate, or both on d 276 of gestation. Cows that received fenprostalene consumed more dry matter (DM) for the last 8 d prepartum than did cows that did not receive fenprostalene (9.6 kg/d vs. 8.5 kg/d, respectively) but consumed less DM for the first 10 d postpartum (10.9 kg/d vs. 13.1 kg/d, respectively). Cows injected with estradiol-17 beta benzoate tended to consume less DM postpartum than did cows not injected with estradiol-17 beta benzoate (11.3 kg/d vs. 12.7 kg/d, respectively). There was no effect of treatment on milk yield; however, a fenprostalene by day interaction resulted from lower milk yield on d 3, 4, 5, 7, and 10 relative to calving in cows that received fenprostalene. Administration of fenprostalene resulted in a delay in the peak plasma nonesterified fatty acid (NEFA) concentration until 2 d after calving. Plasma glucose concentrations were greatest 1 d prior to calving for cows that received fenprostalene, whereas plasma glucose concentrations peaked on the day of calving for cows that did not receive fenprostalene. Liver triglyceride increased over time; however, there was no effect of treatment on liver triglyceride. Calving induction improved DMI for the last 8 d prepartum, but a concomitant decrease in liver triglyceride after calving did not result. Estradiol-17 beta benzoate had no effect on plasma metabolites or liver triglyceride, indicating that the physiological rise in estradiol prior to calving does not have a primary role in lipolysis or hepatic fatty acid metabolism in the dairy cow.

Past studies have shown that use of diluent injection with ESPs can be an efficient artificial lift method for heavy oil fields. It consists of injecting a light hydrocarbon liquid to reduce the oil density and viscosity. This paper describes an integrated modeling solution designed to maximize the reservoir oil production while minimizing the diluent requirement and keeping the crude oil quality within technical and marketing specifications. The field studied is an offshore heavy oil asset. It consists of two reservoirs with API gravities of 14 and 12, and oil viscosities at reservoir conditions of 70 cp and 500 cp. The field includes some 60 production wells. Diluent can be injected (1) in each individual well at the ESP and (2) in the surface processing facility prior to the second stage separator. Operating constraints include (1) minimum wellhead pressure, (2) diluent availability, (3) final crude quality specifications, (4) maximum field oil and liquid production rate. The difficulty of the production optimization problem lies in the nonlinearity of the well production curves and viscosity model. In this paper, we develop a Mixed Integer Linear Programming (MILP) formulation by piecewise linearizing the nonlinear behaviors. For each well at each time step, we adjust the black-oil rates from a reservoir simulator to create piecewise linear well performance curves giving the reservoir oil production as a function of diluent injected at the ESP. The proposed integrated solution is used for the entire production life of the field, which is still in the development phase. The solution is coupled with a reservoir simulator (1) to determine optimal diluent requirements over time, (2) forecast field production of reservoir oil, diluent, water and gas, and (3) foresee eventual bottlenecks in the infrastructure design (e.g. limiting constraints). The proposed solution can easily be used as a Real Time Production Optimization (RTPO) tool to find the optimal operating point based on the latest measurements (or real-time data). The optimal solution ensures the highest field reservoir oil production while meeting all constraints and keeping the diluent consumption at a minimum. The increase of the field oil production rate due to optimal diluent allocation ranges from 2 to 10 %. Cumulative reservoir oil production increases by approximately 3 million std m3. The uniqueness of the solution comes from the integration of all operating constraints into a single mathematical formulation. The computational time (1s – 10s) of the proposed solution outperforms any classical nonlinear approach. This allows running many sensitivity analyses of the entire integrated asset model.

Heavy oil fields can be developed using diluent (light oil, condensate, etc.) injection at the well level as a flow improver. However, diluent can also be injected at the surface, as used in Canadian heavy oil production. Benefits of topside diluent injection include among others (1) improved oil/water separation in the surface processing facility, (2) improved viscosity, and (3) better final crude quality. Such blending activities are often associated with additional OPEX due to the high price of diluent, which can add significant costs to a development. This paper describes an Integrated Asset Modelling (IAM) solution designed to minimize the topside diluent requirement while honouring technical and market crude specifications. The case studied is an offshore heavy oil field consistings of two reservoirs with API gravities of 14 and 12, and oil viscosities at reservoir conditions of 70 cp and 500 cp. The production facilities include a two-stage surface processing facility followed by a coalescer aimed to separate the water from the crude. Diluent is injected in the surface processing facility prior to the second stage separator. Operating variables include (1) the topside diluent injection rate and (2) the temperature of the second stage separator. The difficulty of the production optimization problem lies in the non-linearity of the process and viscosity models, and the consistency of the fluid’s PVT description throughout the production system. The proposed optimization solution is coupled with a reservoir simulator to determine optimal topside diluent requirements over time and foresee eventual bottlenecks in the surface infrastructure design. The proposed solution can also be used as a real-time management tool during the production phase to find the optimal operating point based on real-time data. The optimal operating point ensures the lowest diluent consumption while meeting all system constraints, providing the framework for significant cost savings.