Wettability alteration of the reservoir rock is considered as one of the promising remedies for the condensate blockage. There are key parameters including wettability state (WS), treatment radius ...(TR), and treatment time (TT) that considerably influence this treatment process. The objective of this paper is to conduct simultaneous optimization of WS, TR, and TT in a supergiant gas condensate reservoir located in Persian Gulf offshore. For this purpose, two distinct optimization methods are used in this research. The Taguchi design of experiment (DOE) method is first used to find the optimal state with a low number of simulation runs. Afterward, a smart optimization approach is developed through integration of the artificial neural network (ANN) and genetic algorithm (GA) techniques; this hybrid method helps to assess more possible combinations of the three key factors. Also, the compositional commercial reservoir simulator ECLIPSE 300 is used to simulate gas production operation, considering different WS, TR, and TT conditions. It was found that both the Taguchi and the hybrid constructed network (ANN-GA) methods lead to the results in agreement with the simulation results so that the magnitudes of average absolute relative error are 0.6397% and 0.0436% for the Taguchi and ANN-GA, respectively, based on gas recovery factor (GRF) data. However, the ANN-GA method estimates a slightly higher GRF at the optimum state, compared to the Taguchi. Nevertheless, Taguchi DOE with only 25 required data points seems a promising and practical option for modeling and optimization purposes. The ANN-GA optimum condition corresponds to 50.64% GRF with intermediate WS, a TR of 12.7 m, and a TT of about 5 months.
•Effective approaches to optimize gas condensate reservoirs are introduced.•Interaction between wettability state, and treatment radius and time is considered.•Taguchi method and hybrid ANN-GA lead to outputs close to simulation results.•The optimal treatment time is 150 days based on Taguchi technique.•Wettability state has a higher impact on condensate recovery.
Using vacancy solution theory based on a surface pressure, a thermodynamic model has been developed for prediction of the protein partitioning in aqueous solution in equilibrium with an oil phase ...containing reverse micelles. In the present model, one vacancy solution represents the bulk aqueous phase and the other the reverse-micellar phase. Using the concentration of protein in both reverse micelles and aqueous phase, the surface pressure was incorporated for prediction of the protein adsorption in reverse micelles and the nonideality of the system was expressed in terms of the Wilson activity-coefficient model. The present model has been applied to the extraction of bovine serum albumin with formation of reverse micelles using a cationic surfactant, cetyltrimethylammonium bromide (CTAB), in isooctane-1-hexanol. The results of prediction were in very good agreement with the experiment.
Well production rate is a major factor for simulation of commingled gas wells. It is the base of computations of well flowing pressure, pressure drop, well performance, flow regime, liquid holdup, ...reservoir performance, material balance and average reservoir pressure. Typically, well flow rate is measured using flow meters like orifice, but in some wells flow rates remain unknown due to shortage of flow meters and commingled production.
In this paper, well flow splitting of a gas-condensate field with two platforms is studied. Each platform consists of ten wells and wellhead pressure is controlled by a choke valve. Total flow rate of platforms mixed production is measured after sending their production to refinery. The proposed methodology for dividing total flow between wells consists of choke modeling using test separator data and flow modeling in the wells. Choke models include mechanistic and Ashford and Pierce as theoretical models and Gilbert, Ros and Pilehvari as empirical models. In most investigations choke size is represented with length unit such as inches but in this work, flow is calculated on the base of choke opening percent and choke size as a function of choke opening percent is obtained. Chokes are modeled with upstream temperature, upstream pressure and downstream pressure. Rich gas flow calculations with the proposed method were compared with reported total flow of platforms and showed mean absolute percentage error of 3.2% for mechanistic model as the best of studied models. This error can cause 0.5% error in calculated well flowing pressure.
Sensitivity analysis on operation parameters showed that since the gas-condensate field is lean, gas flow rate is the major phase for modeling and uncertainty of gas-condensate ratio and changing specific gravity and molecular weight of condensate with time do not have considerable effect on well flow rate calculations.
•Choke size as a function of choke opening percent is calculated.•The mean absolute percentage error in the flow calculation of 54 days is 3.2%.•Error of 3.2% in flow rate causes 0.5% error in well flowing pressure calculation.•Probable change of molecular weight and specific gravity of condensate cannot make significant error in calculations.•GCR of flow has no considerable effect on well flow calculation.
Compositional gradient known as a potential of vertically variations in composition (and sometimes areal changes) has a remarkable effect on reservoir management steps such as estimation of initial ...hydrocarbon in place, design of downstream equipments and prediction of gas–oil contact. One of the main steps in development of compositional grading is to characterize fluid sample. In this study, compositional grading is studied in a volatile oil sample from an oil field in south of Iran. Implemented models are based on isothermal and non-isothermal, i.e., zero diffusion, Hasse and Kempers models. Results illustrated that isothermal and zero diffusion models are in appropriate consistency with field data. Then, effect of C
10+
splitting on compositional grading was studied. It was shown that splitting of C
10+
to more pseudo-components does not have significant effect on variation in composition of hydrocarbon and non-hydrocarbon components.
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