Characteristics of Weak-Gel Flooding and Its Application in LD10-1 Oilfield.

Weak gel is a kind of three-dimensional cross-linking system with low polymer concentration and appropriate cross-linking agents, dominated by intermolecular cross-linking, supplemented by intramolecular cross-linking, and with a weak cross-linking degree. In this paper, the microstructure and properties of the weak gel were observed and evaluated under different conditions. Seepage behavior experiments and parallel core displacement experiments were carried out to evaluate profile control and flooding performance of the weak gel. Under a certain polymer concentration, with the increase in cross-linker concentration, the reticular structure of the weak gel becomes more uniform and the strength of the weak gel was further enhanced. Weak gel has more retention in porous media and greater strength. The profile control and flooding performance of the weak gel are much better than those of the polymer. A field test of weak-gel flooding was successfully carried out in LD10-1 oilfield. Most of the production wells around the weak gel injection wells responded after weak-gel injection and the accumulative oil incremental oil production of the test area was 57.8 × 10 m up to December 2018.