Modern methods of enhancing crude oil recovery are being successfully appled at TATNEFT Company in order to increase oil recovery from the fields in the late stage of development.
One way to increase the sweep efficiency of oil saturated reservoirs is injection of guar gum based gel-forming compositions into the reservoir (guar us a polysaccharide of vegetable origin), and combination of “crosslinkers” proposed by experts of TatNIPIneft for the first time (RF patent No.2346151) for full or partial blocking water flushed high permeability zones of the reservoir.
Heterogeneity of the reservoir causes an uneven movement of the displacing agent (water), washed out zones with low filtration resistance are formed, which contributes to premature watering of the wells. At the same time less permeable (low permeability) interlayers are producing at low rates or not at all involved in the development. The gelling composition designed by scientists of TatNIPIneft primarily penetrates into the highly permeable, washed out areas, redistributing the water injected to maintain reservoir pressure to the areas with lower permeability, thereby providing for more complete recovery of crude oil from unswept interlayers.
Varying the concentration of reagents in the guar gum based composition makes it possible to control over a wide range the gellation time and strength properties of gels. Good solubility of this polysaccharide of vegetable origin in cold and warm water, high resistance to mechanical, thermal-oxidative and saline destruction allow application of designed compositions in crude oil production processes with reliable obtaining high-quality working solutions under adverse climatic conditions in Tatarstan’s crude oil fields having a wide range of geological parameters.
Pilot-scale testing of GUAR technology was performed during the period from 2007 to 2009. The technology has been implemented in the fields of OAO TATNEFT since 2011. The current technological efficiency is over 2,000 tons of additional crude oil produced per one treatment.