The Weak Gel Flooding Technology Research

The weak gel flooding technology is developed on the basic of the polymer flooding and the gel water shut-off technology, and due to its profile modification action besides the oil displacement action and which can solve the contradiction between the uprightness and the plane, so which have been paid attention to widely more and more by researcher in recent years. Now, many scholar at home and abroad take up with this study too and have acquired respectable fruits, but there are still many problems unsolved, such as the cross linking and the controlling factor, the characterize and the describing and the measurement of the weak gel, the structure of the weak gel, the gel treatment how to influence the seepage mechanism of the fluid in the petroleum pool and the conditions of the weak gel flooding occurred, and how to prevent the weak gel damage the non-objective stratum and so on, which limit the weak gel flooding to be extended and applied. In order to solve above problems and make full advantage of the weal gel flooding technology, this paper studied this technology systematically.The weak gel is that a few retarding type cross linker is added into the polymer, which the concentration is close to the polymer flooding, and make the polymer be formed the gel system of which the intermolecular cross linking is mostly and the intramolecular cross linking is secondary. So, through widely surveying and a great deal experiments, this paper firstly screened out the polymer host agent which is suited to the weak gel flooding in deep stratum and composed the retarding type organic chromium cross linking agent, and on the basic of that to select the proper stabilizing agent, and compounded with a proper ration to get the deep flooding modification weak gel system. Then, this paper studied systematically the basic property of the cross linking polymer system, on the basic o f which studied the infection of the Shuang He and Xia Er Men locale waste water to the cross linking reaction and discussed all sorts of infection factor of the weak gel property.This paper discussed the cross linking mechanism and used micromillimeter technic to characterize the gel lump structure of the different weak gel types by the atomic force microscope , environment SEM and other means, and analyzed the relation between the gel strength and the gel lump structure and recognized the gel microstructure, and established the foundation for the rheological behaviour of the weak gel forecasting.Through the rheology experiment, this paper analyzed viscoelasticity variation of the cross linking polymer weak gel in different cross linking ration and during the cross linking reaction, and established the constitution equation of the weak gel system, and put forward to the parameter having the physical meaning. Aiming at the characteristic of the weak gel, this paper established a suit of technical method and test criteria to evaluate the strength and the performance of the weak gel. Through the rock core flowing experiment and the data matching, it visually reflected the injectivity, the selectivity , the profile improved degree and other performance of the weak gel, and established the mathematic relation for the viscoelastic modulus, residual resistance factor and permeability, and offered the basal parameter for the numerical model optimized.Moreover, this paper studied the condition of the flooding action occurred and the technology of the weak gel effectively entering into the objective stratum, and discussed the infection mechanism of the weak gel to the permeability rate variation of the oil and water phase. The results indicate that using the weak gel to treat the oil-bearing porous medium will cause the relative permeability of the oil/water phase to be reduced greatly, and the movable saturation scope to be decreased obviously, and the permeability of the different fluids in the porous medium to be increased with the velocity of flow increasing because of the weak gel easily bended performance. Based on above, this paper analyzed the reason that th...