Simulation Study On Water Absorbency Of Water Injection Well Based On Thermal Fracture

Waterflood is the main pattern for maintaining formation pressure in mature oilfield, so it’s necessary to investigate well injectivity decline for the importance of its influence to improve benefits to oilfield. Research shows that thermal fracture plays an important role in injectivity decline, which could not be neglected. For the reason of mastering waterflood performance precisely, it’s important to take a research to study the rule of thermal induction stress.Injecting water into deep, warm reservoirs is a common practice for pressure maintenance, the cooler injection water leads to cooling and thermal contraction of the reservoir rock in the region near the injection well leading to a reduction in the effective fracturing pressure, which come to be known as "thermally-induced fractures". This is a common phenomenon in offshore oilfield. Induced fractures improve the area of injection water loss and creat more grain walls for suspended particles, which reduces the extent of damage for water injection. Thermal fractures allow the well to tolerate a significantly lower quality of water, so it’s instructive to the optimizing of water quality index.Based on studying extensive literature, we have conducted a systematic study of mechanism of suspended particles’migration and blocking and set up a model for evaluation. Besides, with building a model to explain the mechanism of thermal fractures formation and propagation in the cool region. By coupling models we have obtained a model to interprete injectivity decline on the basis of thermal fractures. In the process of model solving, through introducing temperature field calculating, the model can provide temperature difference accurately in any time. Based on the model, we have conducted single factor analysis and comprehensive analysis and got the impact of each factor. Finally, combining the geologic characteristics of X Oilfield and basic characteristics of injection well, we conducted the research of injectivity prediction and confirmed the reliability of the model.