On the prevention of sand formation in oil wells operating from weakly cemented rocks

The development of weakly cemented formations is always complicated by the removal of rocks and mechanical impurities, and solving the problems associated with this becomes the most important task in oil production. These complications are typical for the group of weakly cemented, loose oil fields. The layers being prepared are uncemented sandstone, which means that the equipment operates in conditions of increased abrasiveness. Sand removal is very important. There are also cases when 7–8 sections of pipes above the pump become clogged when lifting equipment. Many methods and technologies are used to remove sand entering the well. However, to regulate the operation of production wells with sand manifestations, it is more expedient not to remove sand from the well, but to strengthen (reinforce) the bottomhole zone of the rock in order to prevent the removal of rock from the bottomhole zone. Form stabilization is the process of stabilizing loose, poorly cemented rocks in the bottomhole zone of oil, gas and water formations in order to prevent large masses of sand from the formation from entering the well. Formation stabilization consists of pumping liquid hardeners into the bottomhole zone of the formation, which, when hardened, should lead to strengthening the rock and increasing its resistance to erosion. At the same time, the permeability values of the layers for liquid and gas should remain close to their initial values. The purpose of this article is to consider the technologies proposed by specialists for preventing the destruction of the bottomhole zone of oil wells operating in poorly cemented rocks, and its stabilization. For this purpose, the causes of rock collapse in the wellbore zone, the factors influencing this process, the problems arising in poorly cemented deposits in oil fields in some countries of the world, as well as the work aimed at solving this problem are analyzed in well-known literary sources. The analysis showed that the collapse of the rocks was caused by both geological factors and violations of technological requirements during the operation of the formation by a well, etc. The causes were also investigated. At the same time, technologies aimed at solving the problem include the selection of plugging materials (compositions) designed to fix the near-wellbore zone prepared by chemical methods, so that the cement stone obtained using this plugging material, in parallel with the increase in compressive strength, increases its own permeability and freely expands in volume.