Researchers from PNRPU have increased the efficiency of oil production using acid solutions. Perm scientists for the first time analyzed the composition of hard-to-reach carbonate deposits and determined the optimal conditions that would allow getting more black gold at minimal cost.
The researchers published the results in the journal Oilfield Business. “Acidic compositions for oil production are widely used, but these measures are not always successful. For example, in the Perm Territory, about 45 percent of operations do not achieve the expected effect. The processes that occur in an oil reservoir when exposed to a chemical solution differ depending on the composition of the rock.
Therefore, it is important to determine the optimal rates of acid composition injection. This makes it possible to obtain extended channels through which oil is filtered - wormholes,”says Dmitry Martyushev, Candidate of Technical Sciences, Associate Professor of the Oil and Gas Technologies Department of PNRPU.
The oil production zone is often contaminated with paraffin deposits, resinous substances, mineral salts and rock particles. Because of this, oil filtration deteriorates, which leads to a decrease in production volumes. To restore the productivity of the well, specialists use acid compositions - most often based on hydrochloric acid with additives to avoid equipment corrosion.
The reason for the low efficiency can be an unreasonable rate of solution supply to the oil reservoir. When the rock dissolves, channels of various shapes and branching are formed, the length and size of which is difficult to determine.
“Methods that allow us to calculate the shape of“wormholes”at the design stage are not always possible to apply in practice. We have determined the optimal injection rate for four acid compositions. For this, we carried out filtration tests on rock samples from oil fields of the Perm Territory with different carbonate content.
In doing so, we simulated the conditions of a real well. Experiments have allowed us to establish that the optimal injection rate needs to be reduced when the carbonate content of the rock increases. In this case, more chemical solution is needed to break through the wormhole,”explains Dmitry Martyushev.
The researchers believe that it is possible to increase the efficiency of oil production by pumping the chemical composition after the breakthrough of the "wormhole" and leaving it in the formation to continue the reaction. This will help to “fork” the main channel and increase its reach. Based on the study, scientists have already made recommendations that will help improve the efficiency of oil production.