Evaluation of a Novel Emulsion Preparation Method for Reducing Water-Cut in Production

Abstract High water cut associated with oil wells can shorten their production life. Globally, water accounted for the majority of the total output from wells. This excess water must be disposed of or treated to a specific standard, depending on the treatment objectives. The industry has developed numerous techniques to decrease the water produced alongside oil production. This study introduces a novel method to pump polymer and crosslinker emulsified system to block water production. The system is designed to gel upon contact with water but form an emulsion in the presence of crude oil. The research was conducted in multiple stages. The objective is to create a water-in-oil emulsion using an emulsifier, introduce the same emulsifier to the crude oil, and then inject the polymer and the crosslinker. The viscosity of the polymer, polymer with crude, polymer with water, crude with emulsifier, and water with emulsifier were recorded. One emulsifier was selected from three emulsifiers when tested with crude oil and water separately the better type was U-108 emulsifier. Then the diluted polymer and the crosslinker were added and the viscosity was measured. The concentrations used in the study and added in the same order are; 53-60 vol. % of water or crude oil, 5 vol. % emulsifier, 2.5 wt. % pH buffer powder, 30-35 vol.% polymer or copolymer, and 4 vol. % crosslinker. These systems were mixed at two different mixing rates to mimic the pumping condition. The initial evaluation of the diluted polymer viscosity at the standard condition and 100 s-1 had a viscosity of 12 cP. The emulsifier raised the viscosity of the linear systems in both oil and water samples, the emulsified linear water has a viscosity of 231 cP at room temperature, compared to 253 cP for crude oil. After 20 hrs at 94 C temperature, the viscosity was 1600 cp for the crosslinked water system and 3300 cp for the emulsified crosslinked water system, the emulsifier raised the viscosity value triple as the non-emulsified system. However, at the same conditions both the crosslinked and emulsified crosslinked crude oil had viscosities less than 20 cp. This preparation method can be applied to the field as a novel pumping method; the pumped emulsifier is proposed to make emulsion when it goes into the oil zone, while no emulsion is formed in the water zone. The formation of the emulsion in the oil zone will prevent crosslinking mechanisms. This emulsion is followed by water which raises the viscosity in the oil zone and not in the water zone which helps in viscous fluid diversion. When the polymer-crosslinker system reaches the water zone the gel is formed as no emulsion formed in the formation. A core flooding experiment was used to prove the two ideas shown in this paper. Two concepts to show in the paper are a) the same fluid pumped into the formation and gelates in the water zone but not in the oil zone, and b) the diverting mechanism based on the viscosity value.