Currently the solutions of organic-silicon compounds are most common means for wells sealing (in their molecules there are bonds between the atoms of silicon and carbon) along with mixes based on sodium silicate (water glass) and hydrochloric acid (hydrogen chloride dissolved in water). However, their use is associated with blocking the gas-and-oil part of the gas-oil bed, which results in reduction of the well deliverability. The alternative is in using bio-polymers, in particular – xanthan, which is a natural chemical compound with good water adsorption and thickening and stabilising properties.
The scientists from Perm Polytechnical University decided to use xanthan as the base for waterproofing gel; its other components are: water solution of magnesium chloride performing as a retarding agent; detergent required for stronger bonding force of the received composition with water; and citric acid strengthening intermolecular interactions.
“The composition is injected into the bed using specialised cementing machines. Usually, it needs to be done quickly to avoid premature gel formation. Our mix has the necessary viscosity and allows for sufficient injection time without exceeding the allowable pressure for cementing machines, i.e., the mix stays fluid allowing for injecting it into the well before the formation of gel”, the Perm Polytechnical University is citing Vadim Derendyaev, the assistant of the oil-and-gas technologies department.
According to the authors of the research, the mix features low viscosity, damage resistance when interacting with stratum water and deep penetration into the bed. These properties will provide for high insulation of wells and for the possibility of using the mix within a wide range of temperatures and in the conditions of high mineralisation of waters.
