| In this study, the objective was to investigate the rheological properties and fluid mechanics of the high pour point crude in Shen84-An12blocks in Liaohe oil field. By analyzing the geology character and the production history, combing the conclusions form the laboratory experiment and the multidciplinary knowledge (such as filtration mechanics in porous medium, petroleum reservoir engineering, and so on), the geological models and numerical models were established, and all of the models were calibrated by the field data. Comparing the different scenario based on the numerical models, the results shown intermediate well could enounce the oil recovery in Shen84-An12blocks in Liaohe oil field.The rheological properties and filtration mechanics of the high pour point crude were studied in the laboratory experiment. Temperature was the main factors affecting the viscosity of the high pour point oil. When the temperature was lower, the viscosity could be influenced by both temperature and shear stress, and the flow of the high pour point oil was a non-Newtonian flow, while the high pour point crude becomes Newtonian flow and the viscosity only relates to the temperature when the temperature was above the melting wax point. The freezing point of high pour point oil changes with the water content. At the beginning, it increases with water content, and freezing point becomes highest when the water content was about70%, and then it decreases with the increasing water content. Due to the affection of the emulsified water, high pour point oil was still a non-Newtonian flow, even if the temperature was above the high pour point oil wax precipitation point.The efficiency of the water driving high pour point oil could be affected by the viscosity of crude oil and the temperature. With the decrease of the oil viscosity and the increase of temperature, efficiency can be improved gradually. In addition, displacement efficiency also has relationship with the rock structure. For example, the poor degree of sorting, small radius of mean value, the core of high shale content may results in the low efficiency of water flooding. With the experimental temperature increasing, high pour point oil reservoir relative permeability curve gradually shifted to the right, the two-phase region widens, the water saturation of isoperm increase, the saturation of combined water increases, the residual oil saturation significantly reduced. When the temperature was lower than the temperature of the wax precipitation point, the curves of relative permeability move to the right with the increasing pressure gradient, the two-phase region becomes wider, and then the pressure gradient increase in order to enounce the recovery.According to the theory of heat transfer, mass balance, energy conservation and momentum conservation principle, the mathematical model of the high pour point oil, which describes the heat transport when the steam injected into the wellbore to the formation, was established. Thwas model could be used to calculate the heat loss. An iterative method was employed to solve the new mathematical model, and established a new approach to evaluate heat losses. This new mathematic model was verified by the data from Shen84-An12blocks in Liaohe oil field. The data included the temperature of steam injection wells, the pressure, and the dryness monitoring data for the high pour point oil reservoir. The results shown the new mathematical model in this study was accurate to calculate the heat loss from the wellbore to the formation, and can be used to evaluate the thermodynamic parameters and the thermal efficiency of the steam in the steam injection process. According to the mathematical model of heat loss using the site basic thermodynamic parameters of steam injection well, the sensitivity of steam parameters were analyzed, and sensitivity law of the high pour point oil steam parameters was obtained.In order to understand the ultimate recovery of the water drive reservoir, the regression prediction method was proposed to automatically search the vale of the initial water content, based on the analysis of existing water drive characteristic curve. The program was written to solve this problem, where this algorithm includes the data preprocessing operation to make this method more accurate, more intelligent. For the some reservoirs experienced several development program adjustments, the segmented fitting the regression method was proposed according to the staging policies by Yuqitai. This data of water content data was smoothed in this algorithm to eliminate the causal factors in the data. This method was tested by the data from Shen84-Anl2blocks, and the results shown this algorithm could get the better prediction. According to the results in this study, the ultimate recovery was29.66%in Shen84-An12blocks. It has not yet reached the final displacement efficiency, and therefore it need to further develop the remaining oil.Based on the statistical analysis of geological and fluid parameters in Shen84-Anl2blocks, the typical geological model and the corresponding five-spot pattern numerical model were established. By comparing the three conventional development methods of water flooding, hot water floods and steam flooding, the results shown that the recovery of Shen84-An12could be improved by steam flooding approach, from both technique and the economic benefit aspects. Based on the analysis of the influencing factors to steam flooding, the sensitivity of the impact factors was investigated. Results shown well distance, steam injection speed, steam injection temperature, mining, and steam injection dryness of steam flooding could affect the oil development. The gray relational analysis method was employed to study sensitivity of the effects of steam flooding to the injection and production parameters, and the influence can be sorted as:steam dryness> production factor> steam injection speed> steam injection temperature>well distance. In the block using steam flooding, three most sensitive factors including steam dryness, production factor, and steam injection speed steam were used to optimize the parameters and obtain the injection and production parameters combination, which was steam injection speed was300m3/d steam dryness0.6above, production factor1.2.Based on the principle of combining deterministic and stochastic theory,3D geological model was established using PETREL software in Shen84-An12reservoir. The reservoir structures model was based on the determinate approach, while, the three-dimensional model of porosity was obtained by optional Gaussian model and sequential Gaussian simulation method, and the three-dimensional model of permeability based on the index model and sequential Gaussian simulation method. Based on the geological model established by PETREL, the numerical simulation models were established in Jing67-59fault block and Jing71-61fault block. By calibrating the numerical models, the fitted model can be used to predict oil flow law. By analyzing the remaining oil distribution in Jing67-59block and Jing71-61fault block, the results shown the relationship of oil distribution with deposition system is not obvious. The oil distribution is mainly related with the micro structure, well network. The main factors affecting the distribution of the remaining oil includes geological factors and development factors, where geological factors includes the structure, the interbeds, faults, and development factors included wells degree of perfection, injection wells affect.In Jing67-59fault block and Jing71-61fault block, cold water injection, hot water injection and steam injection were used to test the development effect using the numerical models, and the results shown hot water injection is better than cold water injection, and steam injection is better than the hot water injection. Therefore, we recommended steam injection should be used to enhance oil recovery in Shen84-An12reservoir.There were two innovations obtained in this study as follows:First, a new mathematical model to calculate the heat loss in the well of the high pour point crude and approach to solve it were proposed when the steam was injected into the strata, based on the heat and mass transfer theory, mass balance, energy conservation, and momentum conservation. This new model can be used to evaluate the heat efficiency and thermodynamic parameters in the procession of the injecting the steam. Finally, this new model was verified by the field data in Shen84-An12blocks in Liaohe oil field.Second, the regression prediction method was proposed to automatically search the value of the initial water content. The algorithm includes the data preprocessing operation to make this method more accurate, more intelligent. For the some reservoirs experienced several development program adjustments, the segmented fitting the regression method was proposed. The data of water content was smoothed in this algorithm to eliminate the causal factors in the data. This method was tested by the data from Shen84-An12blocks, and the results shown this algorithm could get the better prediction. |
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