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This work discusses application of an advanced placement model for optimizing stimulation treatments in high water-cut wells. Stimulation treatments in high water-cut wells are challenging because they can lead to an undesired increase in water production. Associative polymers have been successfully used as diverters for addressing this challenge, and effective treatments have been performed based on experience and guidelines. However, further optimization of such treatments can be achieved using fluid placement models. Model-based treatment design has been described previously but has not been comprehensively applied for diversion by associative polymers. In this work, a transport model was developed for relative water permeability reduction by associative polymers and diversion of stimulation fluids in the pay zone. The model accounted for the mass transport and adsorption of the polymer in the formation. The transport model was integrated into a near-wellbore (NWB) fluid placement model to simulate fluid distribution in a heterogeneous layered reservoir and the effect on total skin, production/injection profiles, and surface/bottomhole pressures (BHPs) during the treatment. The paper describes case studies based on actual field treatments to demonstrate the application of the integrated model for optimizing stimulation treatments. Acid-to-diverter stage volumes, number of diverter stages, polymer concentration, and injection rates are identified as important design parameters. Based on model results, it is observed that polymer placement results in increased total skin in water-bearing zones, leading to lower post-treatment water production. Further, the optimum number and volume of diverter stages for effective diversion vary with injection rate and are governed by the non-equilibrium polymer adsorption behavior and the self-diversion effect during placement. It is concluded a single treatment design might not be suitable across multiple wells, and well-specific optimization of the pumping schedule is necessary. Because multiple parameters affect the treatment, simultaneously leading to results that are not intuitive, the placement model should be used for the treatment design. This paper discusses application of an advanced fluid placement model, which provides insight into the diversion by associative polymers during stimulation treatments. The model is useful for optimizing stimulation treatments in wells with high water cut and reducing costs associated with undesired water production.

In this work a one dimensional steady state model is developed for a single stage and two-stage bottom fed entrained flow coal gasifier for. The single stage model was first analysed for two different oxidants (i) oxygen and (ii) air to study their effects on gasification. Analysis proved oxygen to be the better oxidant. The model is then extended to a two stage gasifier. Here 30 (70) percent of the coal is fed in the first stage (second stage). The first (second) stage operates in oxidant rich (lean) environment. The performances of single stage and two-stage models are compared in terms of their cold gas efficiencies for the same coal feed rates. It is observed that a two-stage system has better cold gas efficiency (77%) than a single stage system (72%) with lower oxygen consumption. The two-stage model is used to optimise the O2/Coal ratio as the H2O/Coal ratio is varied in the 2nd stage. The optimum yields the highest cold gas efficiency with minimum possible oxygen consumption.

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Historically, different fracture diagnostic methods have been used for hydraulic fracturing treatments to obtain estimates of reservoir characteristics, fracture design parameters, and treatment progress. However, the advent of horizontal drilling techniques and expanded interest in unconventional reservoirs has increased the challenges to overcome to achieve a successful hydraulic fracturing treatment. This paper details advancement made to conventional methods of fracture diagnostics to meet these emerging challenges. A comprehensive study was conducted on the latest advancements in different diagnostic techniques. Several published case histories were studied where these techniques were adapted and modified from their conventional form. The effectiveness of the advanced techniques in terms of providing additional information was analyzed. A comparative review of the diagnostic methods was performed to determine individual limitations and to identify fit-for-application scenarios. An attempt was made to classify and categorize them according to the ease of application and usefulness for treatment design and analysis. This study suggests that proper planning, deployment, execution, and analysis of the techniques are essential to helping prevent erroneous conclusions about the treatment and job design. When conducted in unconventional reservoirs, conventional pressure diagnostic methods, as a result of the underlying assumptions of rock properties and fracture geometry, can be interpreted inaccurately. Use of high-fidelity forward models for the inversion of data acquired through these methods can lead to better understanding and help mitigate incorrect interpretation of the results. Similarly, fracture injection-falloff analysis combined with microseismic monitoring and distributed temperature and acoustic (DTS/DAS) data can provide deeper insight into the treatment, particularly for horizontal wells with simultaneously propagating multiple transverse fractures. Thus, a synergistic combination of different diagnostic techniques leads to more effective treatment designs and should be preferred if economically justified. The current work provides information on advanced fracture diagnostic methods and is useful for determining suitable diagnostic techniques for designing hydraulic fracture treatments.