Advanced Materials Research Vols. 807-809

Abstract: In petroleum industry injection of carbon dioxide has a lot of economical advantages for oil recovery. The diffusion coefficient of CO₂ in oil-saturated porous media is a critical parameter. However, there is no universally applicable technique for measuring the diffusion coefficients of gas in oil-saturated porous media. The main objective of this work is to develop a possible experimental method for measuring CO₂ diffusion coefficients in oil-saturated porous media by CT technique. At last the relationship between pressure and diffusivity at T= 29 °C is discussed.

Abstract: Studying the distribution of the remaining oil is a crucial part in the process of developing oilfield. This study provides the further improvement of oil recovery rate with strong guarantee, and is a necessary method of developing further water controlling of individual reservoir oilfield. Saturation measurement techniques for remaining oil distribution research are particularly important. This paper describes the research of ways of measuring saturation in the resistance measurement experiment, the standard resistance - saturation curve and the factors influencing it. The results show that for different electrode installation, standard curve is mainly affected by the electrode distance. Standard curve is also greatly affected by water salinity, temperature and the difference in corespermeability.

Abstract: In pressure drop well test of the clasolite water injection well of Tahe oilfield, through nonlinear automatic fitting method in the multi-complex reservoir mode for water injection wells, we got layer permeability, skin factor, well bore storage coefficient and flood front radius, and then we calculated the residual oil saturation distribution. Through the examples of the four wells of Tahe oilfield analyzed by our software, we found that the method is one of the most powerful analysis tools.

Abstract: At present, the corrosion of the casing near downhole pump suction port is common in some domestic oilfield. In order to study the corrosion mechanism, we design and manufacture a dynamic simulation test device for the corrosion of the casing near downhole pump suction port.The device adopts the single plunger pump and tube and casing string in line with site structure to simulate the intermittent production mode of pump as well as the fluids flow state near the pump inlet adequately, and achieves the corrosion velocity measurement and the research of corrosion behavior under different temperature, CO₂ partial pressure, and velocity. The preliminary experimental results show that the test device has the advantages of reasonable structure, strong simulation and practicality; it provides new methods of testing for the related experimental study under the condition of different corrosion mechanism and has good application prospects.

Abstract: Yubei area exist thick mud shale, mudstone, gypsum mudstone and high pressure brine formation. In the course of drilling, the problems are most conspicuous which include well bore instability, bit balling and so on. In allusion to complex formation and complex accident, the polyamine form strong inhibitory polyamine collapse prevention drilling fluid on the basis of KCl-polysulfonate drilling fluid system was used in Yubei area. After the analysis on the mechanism of the strong inhibitory polyamine polymer drilling fluid system, the polyamine performance evaluation test made in laboratory shows that the drilling fluid system has good rheological property, high temperature resistance, clay and salt water pollution resistance. This drilling fluid system cooperate with KCl improve the ability of inhibition of drilling fluid, meet the requirements of stabilize borehole wall, which carried on the field test in YB A well has obtained good application effect.

Abstract: Polyacrylamide (polymer) solution which has different relative molecular mass and mass concentration in porous media has been studied in seepage flow experiment. Due to differences in pressure drop at different seepage velocities, the effective viscosities of different polymer solutions are calculated. Rheological behaviors of polymer solution changes in different mass concentration and relative molecular mass in porous media are analyzed. It is indicated that in the range of Darcy seepage velocity, acceleration is increasing during the process of pressure drop on both sides of core is resulted from the increase of flow rate during percolation, its effective viscosity first decreased, then increased with the increases of shear rate at range of Darcy velocity. Higher the relative molecular mass and mass concentration lead greater the effective viscosity.

Abstract: The difference between coal reservoir and conventional natural gas reservoir leads to difficulty for fracturing coal seam, also extremely low permeability in coal seam affects seriously the coalbed gas production. However, supercritical carbon dioxide has unique properties that promote pores and cracks, improve coal seam permeability and replace of CH₄ in coal and rock seam. This paper researches on fracturing principle, generational capacity and carrying capacity, anti-reflection effect. At the sametime, based on the problem of change permeability in coal seam, the paper also analyes characteristics of coal reservoir and coalbed gas and combines with properties of supercritical carbon dioxide, which points out the feasibility and necessity that using supercritical carbon dioxide as fracturing carrier in coalbed gas exploitation realizes anti-reflection and increasing production.

Abstract: SP binary composite system can reduce the interfacial tension, has good viscoelasticity, and has similar displacement effect with ASP ternary composite system. In addition, the scaling formation can be weaken because it does not contain alkali. Therefore, it plays a important role in guiding the formulas of SP binary composite system and designing the injection scheme to evaluate the main performance and oil displacement effect of SP binary composite system. Experiments on the main performance evaluation, microscopic simulation model for oil displacement and oil displacement in cores have been carried in this paper, which is intended for the new type of surfactant (HLX-BO1 type)/polymer binary complex system which is applied in SP binary composite flooding test block of Daqing oil field. The emulsification property, adsorption characteristics, stability and rheological property of the SP binary composite system have been evaluated. The oil displacement effect of polymer flooding, surfactant flooding, and SP binary composite flooding have been analyzed in this paper. The evaluation experimental research on SP binary complex system performance shows that: 1The binary composite system has good viscosity stability and interfacial tension stability. 2the emulsification time and emulsification degree both increase With the increasing of surfactant concentration. 3The higher oil content in the oil sand, the greater the surfactant adsorption capacity. 4The concentration of surfactant has less affect on the apparent viscosity of the polymer solution, while alkali has greater influence on the apparent viscosity of the polymer solution. The oil displacement experimental research on SP binary system shows that the oil displacement effect of SP binary system is significantly better than that of the unitary system of polymer or surfactant alone. The oil displacement effect is well whether SP system is flooded after water flooding or polymer flooding. The average enhanced oil recovery rates of artificial cores in the oil displacement experiment are 17.5% and 10.10% respectively. The average enhanced oil recovery rate of natural cores in the oil displacement experiment after polymer flooding is 9.5%.

Abstract: In order to satisfy the plugging demands of injecting the cement plugging agent into reservoirs with different radial depths, the technical studies of cement particle size optimization should be conducted. Through indoor experiment, the relationship between cement particle size and permeability was investigated by both macroscopic and microcosmic analysis. It is observed that the reservoirs which permeabilities are within 50~200mD are matching well with the cement agents which particle sizes are less than 5μm. And the permeabilities within 200~400mD are matching well with the cement agents which particle sizes are within 5~10μm, the permeabilities within 400~700mD are matching well with the cement agents which particle sizes are within 10~20μm, the permeabilities are above 700mD are matching well with the cement agents which particle sizes are more than 20μm. The plugging success rates of all the matching experiments are exceeding 90%. This research result is important to direct the plugging operation in the field.

Abstract: The crack formed under the action of circular medium fluid around the wellbore of brittle shale has been a hot issue in recent years. This paper considers the brittle shale micro fracture formation mechanism from the perspective of inhibitive ability of drilling fluid activity. The model of activity-swelling-hydration is set up firstly through revising generalized Usher model, it states the drilling fluid activity range to keep wellbore in osmotic hydration stage with the critical expansion ratio, thus puts forward the concept of activity window and is verified by indoor test. Results show that the different activity of drilling fluid brings difference in rock strength in macro and time sensitive effect for internal structure of rock in micro. This mechanism can provide a more accurate range design for drilling fluid activity and strong guarantee for wellbore stability.