Matching Relationship and Alternating Injection for Polymer Flooding in Heterogeneous Formations: A Laboratory Case Study of Daqing Oilfield

Abstract

A series of experiments were carried out to study the relationship between polymer and reservoir permeability, as well as the alternating injection pattern for heterogeneous formations. The polymer molecular size (MS) was studied using dynamic light scattering. The parameters such as hydraulic radius, molecular weight (MW), concentrations and salinity were studied. The injection capacity and the relationship between polymer and formation were obtained using injection experiments with natural cores, which represent different regions in the Daqing oilfield. Moreover, an improved injection pattern, alternating injection in heterogeneous formation was studied based on the injection experiments of parallel and in-layer heterogeneous artificial cores. The alternate cycle and slug size were investigated. It was proven that the alternating injection can improve the efficiency of low permeability layers up to 7.3% and a mean value of 4.27%. It was also found that the mechanism of alternating injection is blocking the high permeability layers and improving the water injection profile. We suggest that other fields with high heterogeneity could try the alternating injection to optimize the polymer flooding. Meanwhile, further pilot tests or numerical simulation of polymer alternating injection in heterogeneous formation (formation type II) should be conducted.

Influence of the Injection Scheme on the Enhanced Oil Recovery Ability of Heterogeneous Phase Combination Flooding in Mature Waterflooded Reservoirs

“…In addition, a reasonable injection scheme can reduce the amount of the chemical agent for the purpose of ensuring oil recovery. Nevertheless, previously reported research has been mainly focused on the chemical flooding injection scheme of traditional oil displacement agents such as polymers and focused less on HPCF. − Moreover, previous studies mainly focused on numerical simulation investigation and lacked relevant laboratory physical simulation experiments. In addition, it is not enough to elucidate the displacement mechanism of HPCF with different injection methods from the core scale.…”

Viscosity Loss and Hydraulic Pressure Drop on Multilayer Separate Polymer Injection in Concentric Dual-Tubing

“…Moreover, due to high demand for energy, polymer flooding has been successfully applied in offshore oil production in China [16][17][18][19]. As the development of the oil field, the main objectives of polymer flooding turns into type II formation, which has strong vertical heterogeneity between layers, and the physical properties between the high-permeability and low-permeability layer differ greatly [20][21][22]. Currently, under the low oil price, more recovery efficiency of polymer flooding is required, not only for the heterogeneous reservoir development, but also for heavy oil and offshore polymer flooding.…”

“…The higher the viscosity, the better the displacement effect. Studies have shown that the heterogeneity between layers, and the physical properties between the high-permeability and lowpermeability layer differ greatly [20][21][22]. Currently, under the low oil price, more recovery efficiency of polymer flooding is required, not only for the heterogeneous reservoir development, but also for heavy oil and offshore polymer flooding.…”

Study Rheological Behavior of Polymer Solution in Different-Medium-Injection-Tools

“…Their highly vertical heterogeneities lead to increasing difficulty in injection development. Polymer flooding has been used in Daqing oilfield to improve the contradiction between layers in the process of oilfield development [1,2,3]. The oil recovery can be increased 13% in comparison to that of water flooding [4].…”