Development and application of new enhanced oil recovery methods at the Zhetybai field
Tulesheva Gulnara Dyusenovna
2525.01 - Development and exploitation of oil and gas fields
Field exploitation intensification, stability in hydrocarbon production capacity and oil recovery factor increase are main challenges of the current Oil&Gas industry, including Oil&Gas industry in Kazakhstan.
An oil-recovery method, which involves injection of sodium silicate solution with the addition of carboxymethyl cellulose (CMC) is proposed in the thesis. The concentration of sodium silicate and CMC in the aqueous solution is regulated depending on the temperature at a given reservoir depth and the time required for gellation. The results of experimental studies showed that isolation of highly permeable zones and increasing the formation coverage enables to increase the final oil displacement efficiency up to 19.7%.
Based on the results of investigation, a method for water zone isolation has been developed, including injection of sodium silicate solution containing whey. The concentration of sodium silicate and whey is regulated depending on the temperature at there servoir depth required for insulation. In case of stiff formation medium, fresh or softened water is injected prior to the gel-forming compound.
Acidizing technique has been developed for an inhomogeneous formation with preliminary water zone isolation using a foaming system consisting of an aqueous solution of sodium bicarbonate and a foaming surfactant. An organic acid is injected into the formation prior to the acid solution, while a mixture of ammonium bifluoride, inhibited hydrochloric acid, organic acids and water is used as the acid solution.
The proposed acid treatment technology with preliminary water zone isolation using a foaming system was tested at two injection wells No. 1299 and No. 1410 at Zhetybai deposit. As a result of field trials, well injectivity has increased significantly, as well as oil production rate and the products water cut in the observation wells has decreased. In total, 1654 tons of oil was produced from 9 observation wells within 6 months.