| High pour point oil reservior, a kind of special reservoir type, has to be considered its own characteristics, as a significant difference from general thin oil reservoir in its displacement process. While the research about characterization of this reservoir type, spatial prediction, and the3D geological modeling is still relatively weak, there is a lack of systematic studies and deep analyses. Block Jingguan-2of Liaohe Oilfield is a typical high pour point oil reservoir. The freezing point of crude oil is42℃-64℃, and the wax content is37.5%, which is of the world’s rare type. This paper takes Block Jingguan-2high pour point reservoir as an example and launches a series of researches such as the high resolution stratigraphic correlation of reservoir in the study area, sedimentary system and sedimentary phase analysis, physical property and characterization of hydraulic unit prediction, and water flooding streamline numerical simulation and the comprehensive research of thermal simulation, which is based on a large amount of basic data about geology, core, drilling, seismic, logging, testing and laboratory analysis, and also under the guidance of the theory about the sequence stratigraphy, sedimentology, reservoir geology, logging geology, geological statistics, petrology, petroleum development geology. During the study process, new concepts, new methods and new technology application in data mining research, combined with the computer programming, has comprehensively and accurately identified non-coring section hydraulic unit of Block Jingguan-2reservoir. Then through the indicator simulation technique, the hydraulic unit of the study area was characterized by the description of3D fine geologic model, and permeability was regressed by unit which based on hydraulic unit recognition and division. Moreover, geological body was planted into geological model, and finally the3D quantitative geological model properties were completed to form a set of reservoir3D quantitative geological modeling ideas and methods of this type of reservoir oil and gas exploration for the next step and also provided a reference for reservoir prediction. Based on the streamline numerical simulation of hydraulic unit, we make clear the compatibility relation between the remaining oil in Block Jingguan-2and the injection-production flow line and hydraulic unit. Above all, combined with water injection development of the static damage experiment test data and injection wells formation temperature field mathematical model of reservoir in Block Jingguan-2reservoir, this study searched for the best ground water temperature of the block; combined with reservoir test data and analysis the high wax content and high solidifying point of crude oil simulation on the characteristics of the impact on crude oil seepage process, this study focused on the effects of water temperature on the reservoir development and made the prediction of each development plan by using the numerical simulation method.This paper is divided into8parts. The first part mainly summarized the domestic and international research status and the development trend of the hydraulic unit, and concluded the geological data mining method which was applied for hydraulic unit prediction as a main trend. According to the understanding of the reservoir, this paper summarized some cognitive problems of reservoir hydraulic units; and further concluded the residual oil distribution mode, distribution law and development mode of high pour point oil, which were the main factors that influenced the residual oil distribution; also introduced some existing problems about residual oil distribution research; then put further research content plans and prospects forward.The second part applied the analysis method of Cross the cyclicity of sequence stratigraphy for the high resolution statigraphic framework in Block Jingguan-2and divided, identified and compared different cycle time stratigraphic unit by the means of the geological-seismic-logging joint interpretation technology. Through the vertical sequence, lithology stratigraphy and logging response, and seismic information, this part confirmed that sequence stratigraphic framework was consisted by5long-term base level cycles of Block Jingguan-2in three periods, among them, SQ5was equivalent of S31stratum which was eroding in this block; SQ4was composed by3medium-term base level cycles and8short-term base level cycles; SQ3was composed by3medium-term base level cycles and7short-term base level cycles; SQ2was composed by4medium-term base level cycles and4short-term base level cycles. Those are3mainly obvious water effects during the deposition period of Shahe Street Group.According to the sedimentary sand body of Block Jingguan-2, this study first analyzed the supply of sedimentary background, sedimentary environment, source and electric character of rocks. On this basis, we focused on the analysis of classification, recognition of depositional system and depositional model.In data processing, based on sedimentary and tectonic phase comprehensive research and amount of artificial drawing, this part set a contemplation of three-dimensional quantitative model of structure and sedimentary phases of Block Jing-2. In the tectonic geological modeling, we used the thickness of interpolation surface to control the interzone difficulties, and the final established structure model which was kept structure characteristics and relationships of each layer in the3D space coordination. The sedimentary microphase model was constructed by sequential deposition trend surface control which could indicate the simulation method to simulate an ideal result.The third part, in terms of the reservoir geology of research target and the mercury intrusion analytic data, made a relationship between the index FZI of flow zone and the displacement pressure (Pd), and optimized parameters which had higher correlation with FZI and involved into the classification and clustering at the same time, to obtain4basic scheme:HU#5, HU#6, HU#7and HU#8.According to the Spearman non-parametric correlation coefficient method, this part made the coring well logging parameters associated with FZI values for correlation analysis and selected2kinds of logging curve to build log frequency range. Combined with Bayesian inference written software, the reservoir non-hydraulic unit coring wells was well predicted and verified. Then the result compared with the recognition technology and discriminant results of mature neural network pattern, and presented the closed prediction hit ratio, which had certain application values.After the hydraulic unit well data was prepared, this study simulated the hydraulic unit3D quantitative modeling of reservoir by using sequential indicator and matched the deviation and probability for every unit layer. At last combined with geological method, we did the validation analysis of the outward hydraulic unit model in the two aspects of dynamic and static geological concepts. In the dynamic verification process, this paper summarized9production wells data combined with lateral analysis model of rationality; static verification was analyzed through2wells and well profiles on the lithology, pore throat radius and the corresponding conditions of hydraulic units.The fourth part mainly built the porosity, permeability interpretation model of Block Jingguan-2, and at the same time presented the mathematical model which implanted geologic body to establish3D simulation model of quantitative compound in the study area. Porosity interpretation model was regressed by the binary regression method, and the effect of the regression equation application was good. On the premise of sedimentary phase control, the paper analyzed the porosity data of every layer and every phase, and adopted the method of sequential Gaussian simulation to simulate the porosity distribution quantitatively in the study area.Permeability interpretation model abandoned the traditional prediction methods, but the index and power law relationship model was applied to establish the permeability-porosity relation for each type of reservoir by using the reservoir core hydraulic unit classification. The result was overall optimistic and showed that the best matching relationship model was participated in the calculation with the prediction of permeability and the geological body was planted into the mathematical model. This part verified the permeability precision of the3D model respectively from the plane and vertical. The results showed that the overall distribution characteristics of the permeability3D model was identical to the development scale of sedimentary phase and the information of the reconstructed profiles also proved the reliability of the model.In the fifth part, the method of reservoir engineering was applied to predict the reservoir recoverable reserves and the ultimate recovery. To begin with the summary of4kinds of different regressive models, this paper contrasted the meaning of different model parameters, and searched for the best model for Block Jingguan-2to express the declining production of high pour point oil reservoir.The data calculation and comparison of the actual development in the study area presented that the simulation results of Li-Home model was less than that of the Arps index model and the calculation results of Correa model matched the predicted values of mathematical model well. The results showed that the limited use of Arps model was not generally based on the adjustment of significant measures; too fast rise of the water content in the high pour point oil through water flooding might lead to the lower calculation results of Li-Home model; the β value range of Correa model was expanded with the condition of the work area reservoir, that was the same reliability beyond the range-1<(3<0, and as β value went lower, the declining law was more closed to the law of high pour point reservoir.The sixth part summarized the mathematical model of hydraulic unit under the condition of the reservoir development course and oil-water two phase. Then combined with the geological model of Block Jingguan-2, fluid and percolation characteristic parameters and production data, this part used the streamline numerical simulator to simulate and match the oil-water movement law.Through dynamic analysis of reservoir development and streamline numerical simulation based on hydraulic units of reservoir, this paper accurately predicted the residual oil distribution, at the same time analyzed the compatibility relation between residual oil and water driven injection-production flow line and mobile cell. The reservoir was thought to go through five major adjustments till now. And the water flooding streamline basically covered the entire area, while the residual oil enriched mainly in injection streamline waves and the poor hydraulic unit area (anisotropic residual oil in inner layers and interior layers), contact position of different hydraulic units, imperfect spacing area of injection-production well (interwell retention area) and the fault edge region.Combined with the compatibility relation between water injection flow and hydraulic unit and residual oil distribution, and geological data, this part summarized the complex distribution of residual oil after developing the Block Jingguan-2, respectively from these three aspects:the geological factors, factors of oil and water alternating flooding and development factors, to summarize the main control factors of residual oil distribution.After doing some researches about the reservoir damaged by injection development, thermal physical simulation and thermal numerical simulation research, the seventh part pointed out that the low recovery of some production wells in Block Jingguan-2was mainly related to fluid properties, and production and injection wells near the wellbore reservoir were damaged seriously, and showed that the fluid had non-Newtonian fluid properties. The reason of the stratum damage was because the bottom temperature of the injection-production well dropped, then leading the gas expansion, paraffin wax crystallization and precipitation. The water flooding experiments and phase permeability experiments were carried out respectively during the thermal physical simulation, and the result showed that the water displacement efficiency of high pour point oil reservoir was affected by viscosity of crude oil and experimental temperature; with the loss of the crude oil viscosity and temperature rise, displacement efficiency gradually improved; displacement efficiency was related to rock structure itself, that with small poor sorting, median radius and high shale content of the core, the water displacement efficiency was low; with the increase of experimental temperature, relative permeability curve shape of high pour-point oil reservoir gradually offset to the right, and two phase zone got width, such as water saturation of isotonic points increased and irreducible water saturation increased, while residual oil saturation was significantly reduced; and when the temperature went below the temperature of wax precipitation point, the relative permeability curve moved right as the pressure gradient increased, two phase zone got widened, and the recovery efficiency improved. Thermal physics experiments made the understanding of reservoir fluid properties in the work area clearer, at the same time the experimental data was well prepared for thermal recovery numerical simulation.Under the consideration of the temperature field mathematical model of wells and formation which could transfer the heat and mass in injection wells between oil layers and through different injection temperature programming calculation of the layer deep-intersection chart, the result showed that before the injected water reached the goal layer, the influence of heat loss weight large. After getting to the destination layer, the wellbore temperature, affected by the temperature of the reservoir, rose gradually, and the stratum temperature outside the wellbore presented recovery trend under the common action of the injected water and reservoir itself. The chat of injection temperature80℃reflected that above this temperature, the layers could keep the stratum temperature at the average wax temperature (60℃), while beyond80℃, it was not that different from the temperature increasing effect of the reservoir, which was also verified in the thermal recovery mathematical model. The heating costs must be increased if we continued to increase injection temperature, therefore80℃was selected to be the best temperature for ground water injection, which both took the production cost into account and reduced the reservoir cold damage to achieve the purpose to increase the production. Thermal recovery model analyzed the reservoir development effect of different injection water temperature, the influence of bottom pressure and reservoir water absorption capacity, and analyzed the compatibility relations between different types of reservoir temperature field and residual oil field. The plane distribution of oil saturation layout reflected that the small layer water injection, under the condition of conventional water flooding, damaged the reservoir by affecting oil displacement efficiency. Simulation results also showed that under the water injection temperature of dominant ground, considering both economic benefits and the longer soaking time of reservoir temperature, it was favorable to enhance the efficiency and increase the production.The eighth part conducted a comprehensive summary for the whole paper framework.While the high pour point oil reservoir of Block Jingguan-2in Liaohe Oilfield existed serious heterogeneity which led to some problems during the development process of the reservoir, this paper conducted the residual oil distribution researches of hydraulic unit subdivision and hydraulic units, and formed a integrated set of theory and method which could apply for the hydraulic unit division, correlation, prediction, characterization and application of high pour point oil reservoir; it also explored the multiple classification methods of hydraulic unit space forecast and evaluation method of plane distribution; it made some progress in residual oil streamline simulation and the compatibility relation between injection-production flow line and residual oil, which had important guiding significance in the same type of reservoir exploration. |
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