Advanced Materials Research Vols. 734-737

Abstract: Internationally the research of low permeability oil reservoir is a difficult point in the exploration and development of oil and gas field. This thesis, based on the research methods of low permeability reservoirs at home and abroad, summaries several major problems encountered in the process of low permeability oil exploration and development under the current technical conditions as well as the corresponding, but more effective technical measures that need to be constantly improved. And that exploration and development of low permeability of the reservoir will be the main battle field for some time in the future of oil exploration and development.

Abstract: Aiming at the development of remaining oil after polymer flooding, the author develops an oil displacement technology, alternately injecting the slug of the gel and polymer/surfactant compound system, which can advanced improve the remained oil after polymer flooding. By using the artificial large flat-panel model, the oil displacement experiments are carried on to study the injection characteristics and the displacement efficiency of the alternately injecting the slug of gel and polymer/surfactant compound system, and whether the following water should be injected after polymer flooding has been discussed. The experimental results show that, the recovery of alternately injecting the gel and polymer/surfactant slug after polymer flooding could enhance recovery more than 10% on the basis of polymer flooding, the following water after polymer flooding has a little impact on the final recovery but increasing time and the difficulty of development. Therefore, these results provide the technology that alternately injecting the slug of the gel and polymer/surfactant could advance develop the residual oil and enhance the recovery after polymer flooding.

Abstract: Formation porosity near the wellbore can be changed by massive sand production, so it is impractical to use the initial formation porosity in downhole operation design in unconsolidated sand reservoir. The numerical method for sand prediction is limited for its complicated calculation procedures. An analytical model for porosity variation calculation is developed by coupling the material balance equation with the critical fluid drag force. With the result of sand production simulated test, the model can quantify the relation between sand production rate and formation porosity variation. Application of the model in oil field shows that it is simple and practicable for field engineering design.

Abstract: The Qijia oilfield is a low permeability reservoir, and it is difficult to inject water. For improving the water injection capability of Qijia oilfield, the experiments of water sensitivity and scaling evaluation are developed, and so on. But these experiments are the evaluation about single element. The actual situation of reservoir is not reflected accurately by this way. For determining the main element of water injection difficulty in Qijia oilfield, the experiment of core scaling after water sensitivity is carried on. It is known that the damage ratio to the permeability of core scaling after water sensitivity is more than the simplex scaling through comparing this experiment to the simplex scaling experiment. The reason is that the sloughed clay granule is existed in core after water sensitivity, and the new crystal nucleus is provided for scaling crystal. At the same, the inside wall of core porous channel is becoming coarse, the contact area is increased with the fluid, and it is instrumental for the adhesion and deposition of scale.

Abstract: In view of the formation characteristics of the Qiongzhusi formation in Sichuan Basin and using the Stimulated Reservoir Volume (SRV) concept for reference, fracturing design of well W201 is completed and field tests are successfully conducted. Through evaluation and analysis of the sand fracturing data and by combining some practical experience of the shale gas multistage fracturing in North America, the difference between SRV in shale gas and traditional fracturing is proposed and inspirations is obtained, reference and guidelines for the development of shale gas in China are supplied.

Abstract: With the development of marine oil going to the deeper water area, SPAR platform with its many advantages has gradually become the mainstream of the offshore oil and gas production facilities. In this paper, the Spar platform three-dimensional hydrodynamic model establish is established firstly, then the floating body hydrodynamic is calculated by using the three-dimensional flow theory to get Spar platforms transfer function and hydrodynamic parameters of its motion response. At last, the frequency domain for floating body and mooring system coupling calculation model is analyzed.

Abstract: After used technology of the ASP flooding in the fourth plant of Daqing oilfield, the problem of scaling becomes serious in oil wells. The scale samples do not dissolve to acid or alkali, and it difficult to be treated with regular method, so it has influenced the normal proceeding of well production. For solving this phenomenon, the displacement experiment was proceeded to simulate the site actual oil production conditions by using the high pressure physical simulation tests. By measurement of variation law of permeability in the process of ASP flooding and pH value in produced liquid along with time, the paper predicted the starting time and duration of scaling during oil well production. And rationality of the prediction results was verified by using the local test results. Finally the prediction formulas of scaling time which the oil wells with different spacing in ASP flooding were summarized.

Abstract: Low-permeability gas reservoirs are influenced by slippage effect (Klinkenberg effect) , which leads to the different of gas in low-permeability and conventional reservoirs. According to the mechanism and mathematical model of slippage effect, the pressure distribution and flow state of flow in low-permeability gas reservoirs, and the capacity of low-permeability gas well are simulated by using the actual production datum.

Abstract: Production prediction model and waterflooding characteristic equation considering threshold pressure were deduced. Based on them, a combined solution model was established, which can predict development indexes in low permeability reservoirs. The development indexes of a typical low permeability block YS2 were forecast using the combined solution model. Forecast results and actual production data fit well, which confirms the practicability and validity of the combined solution model. It has important practical significance to guide low permeability oilfield development.

Abstract: Following the criterion of zero pollution for non-target layer, an optimization model for multi-layer reservoir profile control was established by reservoir engineering method. Combining the selective injection mechanism of profile control agent, the whole injection process of profile control agent was simulated by the iteration calculation method of time step splitting. Firstly, the activated range of profile control layer was judged by means of threshold pressure of each formation; secondly, the flow rate of profile control agent was distributed by the water absorption index of each layer; finally, the wellhead injection pressure was calculated base on the pressure equilibrium mechanism. The model not only can be used to optimize the injection displacement and total injection volume of profile control, but also to predict the grading pressure during the process of profile control. In addition, the sensitivity of parameters in this model was analyzed, such as injection displacement, viscosity and resistance factor. Ultimately, the optimal design of injection parameters of profile control for an actual well group was put into practice.