Remaining Oil Distribution Law and Development Potential Analysis after Polymer Flooding Based on Reservoir Architecture in Daqing Oilfield, China

Abstract

Polymer flooding has drawn more and more attention in the world for its high incremental oil recovery factor and relative low costs compared with water flooding and other chemically enhanced oil recovery techniques. However, for many oilfields, such as Daqing Oilfield, China, that have already been flooded with polymers, how to further improve recovery remains a big problem. Traditional intralayer, interlayer and plane heterogeneity studies cannot accurately characterize the remaining oil distribution after polymer flooding. To solve this problem, we established a method to quantitatively describe the reservoir’s architecture. Then, the architecture elements were dissected hierarchically and the interface of each architecture level in Daqing Oilfield was identified. The distribution pattern and development potential of the remaining oil after polymer flooding under the influence of reservoir architecture was analyzed. The results show that, regarding the sedimentary process from north to south in Daqing Oilfield, the channel becomes narrower, the thickness decreases, the point bar’s width increases and the thickness of the meandering river decreases. The braided bar scale becomes larger and the thickness becomes smaller in the braided river. According to the reservoir’s architecture, the remaining oil was divided into four categories of plane remaining oil (abandoned channel occlusion type, interfluvial sand body occlusion type, inter-well retention type and well pattern uncontrollable type) and three types of vertical remaining oil (in-layer interlayer occlusion type, rhythm type and gravity type). About 40% of the original oil in place (OOIP) of Daqing Oilfield has not yet been produced, which indicates that there is great potential for development. This study is important for improving oil recovery in polymer-flooded reservoirs.

Microscopic Remaining Oil Distribution Regularity and Enhanced Oil Recovery Methods after Polymer Flooding

“…Based on the microscopic remaining oil distribution test results, combined with the reservoir numerical simulation in the test areas after polymer flooding, the laboratory physical simulation experiment results, and the research literature, Table summarizes the distribution types, causes, and state of remaining oil after polymer flooding. − …”

“…Nearly half of the geological reserves still stay underground, which are high-quality resources for the sustainable development of the Daqing oilfield. , Owing to the deep development of water flooding and polymer flooding, the remaining oil distribution after polymer flooding is highly dispersed, and the proportion of medium to strong-washed layers is large. The oil-displacement mechanism becomes more complex due to the presence of residual polymer, and it is more difficult to develop further. − It is urgent to study systematically the distribution regularity of remaining oil after polymer flooding, and we try our best to tackle key problems of significantly enhancing oil recovery technology on this foundation.…”

Quantitative Scale Analysis of the Channel Bar in a Braided River and Its Internal Architecture

“…(3) Single Accretion Calculation On the basis of the architecture interface identification of the accretion and the calculation of its inclination angle, combined with the empirical formula and the interwell comparison method in the dense well area, the scale of the single accretion in the channel bar can be determined. According to the empirical formula for the size of the single accretion from Kelly [38], the width of the single accretion can be calculated through its thickness.…”

Study on the rheological behavior of aqueous solutions of polyacryloylglycinamide

“…At present, polymer flooding 1,2 is the most widely used means of tertiary oil recovery technology due to its better oil flooding effect, and it is also one of the key initiatives for enhanced oil recovery (EOR). 3–6 Its oil repulsion mechanism 7 uses an aqueous polymer solution to increase the viscosity of the repellent medium, increase the fluidity ratio between the repellent phase and the repelled phase, and increase the ripple coefficient.…”