Microscopic Conductivity Mechanism and Saturation Evaluation of Tight Sandstone Reservoirs: A Case Study from Bonan Oilfield, China

Sun, Jianmeng; Feng, Ping; Chi, Peng; Yan, Weibo

doi:10.3390/en15041368

Cited by 3 publications

(2 citation statements)

References 56 publications

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“…The rock electric theory (electrode method) was based on Archie's formula, a fundamental relationship capturing the interplay between rock electric parameters, such as resistivity, porosity, and water saturation. Archie's equations are presented as follows [28][29][30]:…”

Section: Experiments On the Oil Displacement Effect Evaluation Of The...mentioning

confidence: 99%

Experimental Study on Enhanced Oil Recovery of Adaptive System after Polymer Flooding

Pi,

Fan,

Liu

et al. 2023

Polymers

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After polymer flooding in Daqing Oilfield, the heterogeneity of the reservoir is enhanced, leading to the development of the dominant percolation channels, a significant issue with inefficient circulation, a substantial amount of displacement agents, and elevated cost. In order to further improve oil recovery, an adaptive oil displacement system (ASP-PPG) was proposed by combining preformed particle gel (PPG) with an alkali-surfactant-polymer system (ASP). This comprehensive study aims to assess the effectiveness of the adaptive oil displacement system (ASP-PPG) in improving the recovery efficiency of heterogeneous reservoirs after polymer flooding. The evaluation encompasses various critical aspects, including static performance tests, flow experiments, microscopic experiments, profile control experiments, and flooding experiments conducted on a four-layer heterogeneous physical model. The experimental results show that the adaptive system has robust stability, enhanced mobility, effective plugging capability, and profile improvement capability. Notably, the system demonstrates the remarkable ability to successfully pass through the core and effectively block the large pores, resulting in an 18.4% recovery incremental after polymer flooding. This improvement is reflected in the reduced oil saturation values in the ultra-high permeability, high permeability, medium, and low permeability layers, which are 5.09%, 7.01%, 13.81%, and 15.45%, respectively. The adaptive system effectively recovered the remaining oil in the low and medium permeability layers, providing a promising approach for improving the recovery factors under challenging reservoir conditions.

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Section: Experiments On the Oil Displacement Effect Evaluation Of The...mentioning

confidence: 99%

Experimental Study on Enhanced Oil Recovery of Adaptive System after Polymer Flooding

Pi,

Fan,

Liu

et al. 2023

Polymers

View full text Add to dashboard Cite

show abstract

“…The complex geological processes in low-permeability tight sandstone reservoirs have resulted in a complex pore structure characterized by the disappearance of primary pores and the prevalence of dissolution pores. As a result of this complex pore structure, traditional saturation models are ineffective for evaluating logging saturation in low-permeability tight sandstone reservoirs [7][8][9][10][11]. The saturation model based on the rock physics volume model utilizes the theory of multiple connected pores for electrical conduction, essentially taking into account the electrical conductivity of water in the formation.…”

Section: Introductionmentioning

confidence: 99%

Three-Water Differential Parallel Conductivity Saturation Model of Low-Permeability Tight Oil and Gas Reservoirs

Hu,

Cheng,

Zhang

et al. 2024

Energies

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Addressing the poor performance of existing logging saturation models in low-permeability tight sandstone reservoirs and the challenges in determining model parameters, this study investigates the pore structure and fluid occurrence state of such reservoirs through petrophysical experiments and digital rock visualization simulations. The aim is to uncover new insights into fluid occurrence state and electrical conduction properties and subsequently develop a low-permeability tight sandstone reservoir saturation model with easily determinable parameters. This model is suitable for practical oilfield exploration and development applications with high evaluation accuracy. The research findings reveal that such reservoirs comprise three types of formation water: strongly bound water, weakly bound water, and free water. These types are found in non-connected micropores, poorly connected mesopores where fluid flow occurs when the pressure differential exceeds the critical value, and well-connected macropores. Furthermore, the three types of formation water demonstrate variations in their electrical conduction contributions. By inversely solving rock electrical experiment data, it was determined that for a single sample, the overall cementation index is the highest, followed by the cementation index of pore throats containing strongly bound water, and the lowest for the pore throats with free water. Building on the aforementioned insights, this study develops a parallel electrical pore cementation index term, ϕm′, to account for the differences among the three types of water and introduces a parallel electrical saturation model suitable for logging evaluation of low-permeability tight oil and gas reservoirs. This model demonstrated positive application effects in the logging evaluation of low-permeability tight gas reservoirs in a specific basin in the Chinese offshore area, thereby confirming the advantages of its application.

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Dielectric properties of porous rocks with partially saturated fractures from finite-difference modeling

Bao

Han

2022

GEOPHYSICS

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Fractures are common features of geological rocks, and have a profound influence on the fluid flow and transport characteristics as well as physical properties of the fracture-bearing rocks. Fractures are frequently partially saturated in hydrocarbon reservoirs and the dielectric properties that are highly sensitive to the fluid types and concentrations are useful tools for the quantitative characterization of reservoir rocks with partially saturated fractures. However, the effects of partially saturated fractures on the dielectric properties of porous rock are still poorly understood. Based on a three-dimensional finite-difference model, we bridge this knowledge gap by studying the frequency-dependent dielectric properties of a porous carbonate rock with partially saturated fractures obtained by the brine-displacing oil simulation. We find that the conductivity and high-frequency (higher than about 1 MHz) relative permittivity generally increase, while the low-frequency relative permittivity and peak dielectric loss decrease with the increasing brine saturation. We also find that the partially saturated fractured rock with lower brine saturation exhibits a greater low-frequency relative permittivity and maximum dielectric loss factor than the cases when the fractures are completely filled with oil. Systematic investigation based on simplified intersecting fracture models suggests that the oil-brine distribution is the main reason for the abnormal dielectric responses of the low-frequency relative permittivity and the maximum dielectric loss factor at low brine saturations. The results provide new insights for the comprehensive understanding of the frequency-dependent dielectric responses of fractured sedimentary rocks, and will pave the way for the quantification of the brine saturation in partially saturated fractures.

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Microscopic Conductivity Mechanism and Saturation Evaluation of Tight Sandstone Reservoirs: A Case Study from Bonan Oilfield, China

Cited by 3 publications

References 56 publications

Experimental Study on Enhanced Oil Recovery of Adaptive System after Polymer Flooding

Experimental Study on Enhanced Oil Recovery of Adaptive System after Polymer Flooding

Three-Water Differential Parallel Conductivity Saturation Model of Low-Permeability Tight Oil and Gas Reservoirs

Dielectric properties of porous rocks with partially saturated fractures from finite-difference modeling

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