Experimental Study on the Transport and Improved Oil Recovery Mechanism of Submicron Particle Gel

Excessive water production could cause rapid decline in well deliverability and may lead to early well abandonment. Submicron polymer particle gel is a relatively new remedial treatment for excessive water production problems. This novel water control system can be adjusted according to formation pore throat sizes, particularly for deep profile control. However, current publications only introduced their physical properties and field applications. Moreover, no lab results have been reported about their transport behaviors and oil recovery improving abilities. This work investigated the transportation of a submicron particle gel system into porous media to block high permeability water flow channels. Coreflooding experiments on Berea sandstones were conducted not only to examine the water blockage mechanisms, but also to understand the potential improvement in oil recovery. Concentrations of submicron particle gel and brine are the two major factors that can potentially affect the efficiency of the water blockage and oil recovery improvement. Therefore, effect of these two parameters were thoroughly investigated in this experimental study. Meanwhile, to observe the in-depth transport of the submicron particle gel, the core holders with multiple pressure taps were used to monitor pressure drop at different sections and identify where the particles were transported. In the first part of the research, three different submicron particle gel concentrations were involved. The injection volumes of submicron particel gel dispersion were kept same in all coreflooding experiments. Result shows that the particle gel can transport deeper into the core, yields better impact on the efficiency of water blockage and result in higher oil recovery improvement when the gel concentration was higher. The second part of the research studied the impact of brine concentration. With difference in salinity environments, submicron particel gel had different swelling ratios and strengths: swollen particles were bigger and weaker with lower salinity. Unlike previous research, submicron particle gel was injected until a stable injection pressure in all sections of the core. Results indicate that high salinity environments could result in better plugging efficiency however low salinity environments could result in better oil displacement efficiency. The reasons behind the results have been analyzed by evaluating the submicron gel physical and rheology properties in lab. By studying the impacts of these two factors, this work provides a better understanding of submicron particle gel transportation and oil recovery improvement mechanisms, which is of major importance for an optimized design of a successful submicron particle gel treatment