Hanqiao Jiang

Study of Interfacial Tension Between Oil and Surfactant Polymer Flooding

Abstract Surfactant polymer flooding is an important technology for enhancing oil recovery. It is generally thought that the lower the interfacial tension (IFT) between the combination flooding and oil is the higher oil recovery is. Some physical stimulation experiments have been conducted to show that a system with low IFT could bring better oil recovery than one with ultralow IFT in heterogeneous reservoirs. Emulsion experiments and visual experiments have also been carried out to determine the reason. This article presents results of those experiments and gives the possible mechanism of those results.

The Influence of the Combination of Polymer and Polymer–Surfactant Flooding on Recovery

Abstract Polymer–surfactant flooding is able to enhance oil recovery greatly because it can improve sweep efficiency and displacement efficiency. However, the surfactant is so expensive that it is impractical for widespread use. After experiments were carried out to evaluate the polymer and the surfactant used, in this article we suggest that combined polymer flooding slug and polymer–surfactant flooding slug should be good for high recovery and low cost. Many physical simulation experiments were conducted todetermine the optimal proportion of slug combination. Mechanisms of slug combination are discussed in this article.

An Analytical Model for the Early Stages of Polymer Flooding

The threshold pressure gradient (TPG) was proved existent by laboratory experiments, and the relation between TPG and permeability is obtained. A new analytical method considering TPG, wellbore storage as well as skin effect for polymer flooding is presented. The results of the model are in good agreement with the field data. It is shown that the bottom-hole pressure differential is higher when considering TPG and the injective is reduced with the increase of TPG.

Chemical Flooding for Enhanced Recovery

Abstract Chemical flooding is an important enhancing recovery technology. Displacement mechanisms of different displacement agents were dissimilar. There were some experiments finished to research the effect of chemical flooding. After evaluation of displacement systems, recoveries of all formulas were determined and the recovery contour diagram was completed. Recoveries obtained in experiments have been compared and influences of several chemicals on recovery have been analyzed. Experimental results showed that sweep efficiency should be more important in enhancing recovery than displacement efficiency. Oil recovery of formulas including alkali would not be good, because alkali led to low viscosity of displacement agents.

Numerical Simulation of Surfactant-Polymer Flooding

We propose a mathematical model (numerical simulation) of surfactant-polymer flooding for a three-phase six-component system. The model takes into account various phenomena inherent to flooding, the effect of surfactant—polymer interactions on the viscosity, interfacial tension, and adsorption. We simulated the behavior of different mixtures of polymer and surfactant characterized by mutual attraction, mutual repulsion, or no interaction. We have studied the effect of volume of injected solution, injection rate, and polymer concentration on flooding performance. Taking into account interaction between the surfactant and the polymer results in a better match between the mathematical model and field data.

Erratum to: Improved Approach to Evaluating the Hydrodynamic Performance of Polymers in the Early Stage of Polymer Flooding

In order to analyze the behavior of a polymer underground in the early stage of flooding, we propose a new method based on power-law steady flow of a fluid, taking into account threshold pressure. We use data from an injection well and geological parameters to calculate the flow behavior index, the average effective viscosity within the polymer-swept portion, the resistance factor, and other important parameters. The reliability of the method is confirmed by comparing the results with data obtained during well development with the results of the ECLIPSE hydrodynamic simulation. The new method lets us track the change in polymer performance over time, and can be recommended for use in drafting recommendations for field development in subsequent stages.

Interfacial Activity and Oil Displacement Efficiency of an Alkyl Glucoside and Petroleum Sulfonate System

A novel binary compound flooding system was developed using the combination of nonionic surfactant alkyl glucoside and anionic surfactant petroleum sulfonate with the mass ratio of 1:1. The interfacial activity was studied by experiments. The results showed that the interfacial tension between a binary compound flooding system and crude oil was reduced to an ultra-low value at 45–80°C, and the compounded system showed good tolerance to salt and divalent cations. Core flooding experiment results showed that the system could further improve recovery after water flooding. Micro-flooding experiment results showed that the system could further start and displace residual oil after polymer flooding.

Study on Injection-Production Well Connectedness Evaluation Method in Polymer Flooding Reservoir

This paper introduces the Grey theory to evaluate the injection-production well connectedness in polymer flooding reservoir. Gery theory can give the law of the data by data analysis and calculation. Through the production data dynamic analysis and calculation using the Grey method, realized the injection-production well connectedness quantitative evaluation in polymer flooding reservoir. Comparing the injection-production well connectedness calculate by the Gery method with the tracer test result shows that using the Gery method to calculate the injection- production well connectedness can get reliable and accurate results. This method can be used to calculate the injection-production well connectedness in polymer flooding reservoir.

Advance Water-Flooding to Reduce the Stress Sensitivity Affect on Low Permeability Reservoir Development

Physical simulation experiments were made to research on the stress sensitivity on physical property of low permeability reservoir rocks. The experimental results shown that effective pressure had good exponential relationship with reservoir permeability. Combining with materaial balance method, reservoir engineering and rational deducation was made to reserach on water-flooding timing of low permeability reservoir development. Several production targets were obtained by these method, such as formation pressure, water and oil production, water cut and so on. The results shown that advanced water-flooding was very important in low permeability reservoir development to reduce the bad impact of stress sensitivity on formation permeability and maintain formation pressure.

Pre-Warning and Decision Making of Water Breakthrough for Higher Water-Cut Oil Field

Major domestic oil fields have entered the period of high water now, however, choosing timing of profile control and water shutoff is always delay, Mostly have to wait until after the adoption of dynamic degradation. This article introduced the concept of early warning that is widely used in military and economic fields to profile control and water shut-off decision-making in high water-cut stage. Combination of actual situation of water shut-off decision-making, Presented a strong adaptive set of Warning signs of indicators, on the basis of the analysis of variation in the warning sighs of indicators, this paper proposed early warning model and processes of profile control and water shut-off. The model not only can give the current degree of a single well, but also can forecast the future degree of change in a period of time, so this modle could provide an effective basis for water shutoff and profile controle decision-makers.