Researchers from PNIPU 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 more black gold to be obtained at a minimal cost.
Researchers published the results in the journal Oil Field. “Acid compositions for oil production are used in large quantities, 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 the oil reservoir when exposed to a chemical solution vary depending on the composition of the rock.
Therefore, it is important to determine the optimal rate of injection of the acid composition. This allows you to get long channels through which oil is filtered – wormholes, ”says Dmitry Martyushev, candidate of technical sciences, associate professor of the Oil and Gas Technology Department of PNIU.
The oil production area is often polluted by paraffin deposits, tarry substances, mineral salts, and rock particles. Oil filtration is deteriorating because of this, which leads to a decrease in production volumes. To restore well productivity, specialists use acid formulations – most often based on hydrochloric acid with additives to avoid equipment corrosion.
The reason for the low efficiency may be an unreasonable rate of flow of the solution into the oil reservoir. When the rock is dissolved, channels of various shapes and branches are formed, the length and dimensions of which are difficult to determine.
“Methods that allow you to calculate the shape of the“ wormholes ”at the design stage are not always possible to put into practice. We determined the optimal injection rate of the four acid formulations. For this, we carried out filtration tests on rock samples from oil fields of the Perm Territory with different carbonates.
In this case, we simulated the conditions of a real well. The experiments allowed us to establish that the optimal injection rate must be reduced when the carbonate content of the rock increases. In this case, to break through the wormhole, more chemical solution is needed, ”explains Dmitry Martyushev.
Researchers believe that it is possible to increase the efficiency of oil production by pumping the chemical composition after breaking through the wormhole and leaving it in the reservoir to continue the reaction. This will help to “fork” the main channel and increase its coverage. Based on the study, scientists have already made recommendations that will help increase the efficiency of oil production.