Oil Recovery In China Research Articles

Study on the Synthesis, Surface Activity, and Self-Assembly Behavior of Anionic Non-Ionic Gemini Surfactants.

The use of surfactants in oil recovery can effectively improve crude oil recovery rate. Due to the enhanced salt and temperature resistance of surfactant molecules by non-ionic chain segments, anionic groups have good emulsifying stability. Currently, there are many studies on anionic non-ionic surfactants for oil recovery in China, but there is relatively little systematic research on introducing EOs into hydrophobic alkyl chains, especially on their self-assembly behavior. This article proposes a simple and effective synthesis method, using 3-aminopropane sulfonic acid, fatty alcohol polyoxyethylene ether, and epichlorohydrin as raw materials, to insert EO into hydrophobic alkyl chains and synthesize a series of new anionic non-ionic Gemini surfactants (CnEO-5, n = 8, 12, 16). The surface activity, thermodynamic properties, and self-assembly behavior of these surfactants were systematically studied through surface tension, conductivity, steady-state fluorescence probes, transmission electron microscopy, and molecular dynamics simulations. The surface tension test results show that CnEO-5 has high surface activity and is higher than traditional single chain surfactants and structurally similar anionic non-ionic Gemini surfactants. Additionally, thermodynamic parameters (e.g., ΔG°mic ΔH°mic ΔS°mic et al. indicate that CnEO-5 molecules are exothermic and spontaneous during the micellization process. DLS, p-values, and TEM results indicate that anionic non-ionic Gemini surfactants with shorter hydrophobic chains (such as C8EO-5) tend to form larger vesicles in aqueous solutions, which are formed in a tail to tail and staggered manner; Negative non-ionic Gemini surfactants with longer hydrophobic chains (such as C12EO-5, C16EO-5) tend to form small micelles. The test results indicate that CnEO-5 anionic non-ionic Gemini surfactants have certain application prospects in improving crude oil recovery.

Enhancing the separation of produced gas and CO2 capture for enhanced oil recovery in China, multi-objective simulated optimization and quantitative assessment for sustainable development

The Belt and Road Initiative proposed by China is a common aspiration of all countries along their routes to achieve sustainable development of the environment, economy, society, and people's livelihood. Recently, prominently raised CO2 concentration in the Belt and Road region is perceived to give rise to these serious greenhouse effects on severe and sustained global warming. It could lead to related climate instability, adverse natural disasters, glacier melting, and extreme weather patterns. CO2-enhanced oil recovery (CO2-EOR) is one of the essential CCU technologies. Due to lacking sustainable quantitative evaluation of CCU technology widely used in promising industries, it is imperative to conduct process simulation and optimization evaluation of CCU technology. Considering the lack of sustainable quantitative evaluation of CO2-EOR, we proposed a multi-objective optimization and sustainable quantitative assessment to provide insights and enhance the separation of produced gas and CO2 capture for CO2-EOR. Their industrial applications before and after optimization were systematically simulated, discussed, and compared. With unremitting efforts, the optimized CO2 capture process can stably separate oil field-produced gas into pure CO2 and oilfield light hydrocarbons, with a mass content of CO2 over 99.7 wt%. The optimized process demonstrated outstanding technical, economic, social, livelihood, and environmental properties. This study will undoubtedly benefit researchers in related fields of CCU process simulation, promote significant breakthroughs in basic research, superstructure, and commercial applications, and provide a perspective for the Belt and Road Initiative to establish better and optimize CCU devices and realize regional and global cooperation, future scientific and industrial progress.

Investment in CO2 capture and storage combined with enhanced oil recovery in China: A case study of China's first megaton-scale project

In recent years, China has accelerated the development of CCUS (CO2 capture, utilization and storage) technology and started construction of the first megaton-scale CCS-EOR (CO2 capture and storage combined with enhanced oil recovery) project. Taking China's first megaton-scale CCS-EOR project as an example, this study constructs a comprehensive evaluation method that integrates the decision rules of the real option approach and net present value approach to evaluate the economics and investment strategies of China's CCS-EOR projects under multiple uncertainties. The results show that the project investment in 2022 can create a profit of 2.94 million USD because of the introduction of a tax credit policy that will begin in 2030 with an initial amount of 10 USD/ton of CERs (certified emission reductions) and an annual increment of 2 USD/ton of CERs, but the optimal time to invest should be 2025. Without this incentive policy, the profit opportunity and ability of the case project will be greatly reduced. In addition, the decision-making of CCS-EOR project investment is extremely sensitive to capital cost, oil production, incentive policy start time, and incentive intensity. Therefore, China should formulate and implement tax credit incentives or similar policies with a high incentive intensity as soon as possible to improve the confidence of potential CCUS investors. Direct financial support for early CCS-EOR projects through government financial allocations should be an important addition. In addition, enterprises should strive to accurately calculate and forecast the capital cost and oil production.

Analysis of water flooded characteristics Qualitative analysis of factors affecting water flooding Horizontal well

In production practice, water flooding is mostly used in oil recovery in China, and water flooding occurs in oilfields due to improper artificial water injection. We must understand the Flooded characteristics to take remedial measures for flooding timely. In addition, compared with vertical wells, horizontal wells have the advantages of high recovery index, low production pressure difference, long waterless production period, and so on. Therefore, this paper will also make a brief analysis of the influencing factors of horizontal well flooding.Therefore, the analysis of the above two aspects can be used to adjust and adjust the oil field plan.

Evaluating the energy consumption and air emissions of CO2-enhanced oil recovery in China: A partial life cycle assessment of extralow permeability reservoirs

Carbon dioxide enhanced oil recovery (CO2-EOR) can capture, transport and store CO2 emitted by high energy consumption enterprises. Therefore, the use of CO2-EOR enhances oil recovery and is also an effective means of reducing CO2 emissions. Currently, energy and environmental assessments of CO2-EOR have been rare in China. In this study, partial life cycle assessment (LCA) is used to evaluate the energy consumption and air emissions gate to grave in a CO2-EOR test station for extralow permeability reservoirs in northern China. The gate to gate of CO2-EOR defines 5 stages: transportation, liquefaction, injection, oil production and recycling. Through the analysis of these stages, the results show that producing one metric ton of crude oil gate to gate consumes 2472.56 kW hours of electricity and emits 2532.63 kilograms of CO2, 74.18 kg of SO2 and 37.38 kg of NOx. Water flooding that occurs under similar geological conditions is selected and compared with CO2-EOR for energy consumption and air emissions. In the case of producing one metric ton of crude oil, CO2-EOR gate to gate consumes more electricity than water flooding gate to gate and emits more CO2, SO2 and NOx. Compared with the amount of CO2 injection, the net CO2 emissions of CO2-EOR gate to gate to produce one metric ton of crude oil are -1675.15 kg, and the net CO2 emissions of water flooding gate to gate to produce one metric ton of crude oil are 775.83 kg. When considering energy consumption in the downstream segments of CO2-EOR, the net CO2 emissions of CO2-EOR gate to grave to produce one metric ton of crude oil are 0.53 metric tons. The results of this study provide valuable insights into the policy implications and sustainable development of CO2-EOR in China.

Advances in ultrasonic production units for enhanced oil recovery in China.

With the development of oil recovery technology, ultrasonic technology has been involved in oil production and oilfield development. The mechanism of ultrasonic wave plugging in near well is different from the conventional oil recovery technology. Ultrasonic oil production technique is an effective method to enhance oil production with low cost, good applicability, and no environmental pollution. The core part of ultrasonic oil production equipment for Enhanced Oil Recovery is a high-power ultrasonic transducer. The continuous high-power ultrasound is used to treat the reservoir, which changes the pore structure, the physical property and the state of the fluid, thus improving the permeability and flows conditions of the reservoir, and increasing the oil yield and oil recovery. Ultrasonic oil recovery equipment includes the generation of high-power ultrasonic signals, long-distance transmission and the conversion of electrical energy to acoustic energy. In this paper, state-of-the-art on the development of ultrasonic oil production devices for Enhanced Oil Recovery in China is introduced. The purpose of this paper is to provide a reference for the development of high-power ultrasonic oil extraction equipment and its promotion in tertiary oil recovery technology.

The Development and Application of the Acrylamide Kind Polymers for Tertiary Oil Recovery in China

As many oilfields shift from high permeability and medium-high permeability to low permeability and ultra-low permeability, the complexity and specificity of their formation channels increase, and the requirements on injectivity and liquidity of polymer flooding become increasingly stricter. This paper, from the perspective of the molecular configuration of poly(acrylamide) (PAM), gives an introduction to their respective characteristics, and analyzes the applicability of PAMs in tertiary oil recovery on the basis of the applications of polymer flooding in China. The study suggests that, on the one hand, the problem that urgently needs to be solved at present is achieving the viscosification of polymers with medium-low molecular weight or low molecular weight in high-temperature and high-salt conditions; on the other hand, researchers shall change their original research thoughts, shift from large-scale design of original PAM products to one-to-one “customized” research on and development for meeting specific oilfield demands from the perspective of polymer molecular structure.

Application of optical sensing system in heavy oil recovery

While the heavy oil recovery in China is switching from the traditional Cyclic Steam Stimulation to the more innovative Steam Assisted Gravity Drainage (SAGD), real-time reservoir monitoring system become more and more important for petroleum industries, but tradition electrical systems’ performance on spatial resolution are not good enough. In this paper, we present an optical sensing system based on OTDR and corresponding interpretation, which can obtain the real-time temperature profile and its spatial resolution and temperature resolution is much higher than tradition electrical monitoring system. We utilized this system into the heavy oil recovery in Xinjiang oilfield, the experiment result shows that the position of steam cavity leading edge. This system can provide deep insight into the status of oil recovery process and provide basic data for the following operation.

Effective Application of Solid Expandable Tubular During the Enhancement of Heavy Oil Recovery in China, Lessons Learned and Experience Shared

As the traditional thermal recovery became less effective in exploring the heavy oil reservoirs, some newly developed techniques such as chemical flooding, SAGD and HDCS are demonstrating their advantage in the recovery process in China. However, the ever increasingly used new techniques often compromised severely the well integrity as the flow of extremely high temperature fluid or gas caused quick damage to casing, leaving the wellbore less reliable. This compromise requires urgently a workover strategy that would maximize the well’s life span and guarantee the effectiveness of new techniques. Solid expandable tubular (SET) was field-proven in casing patching activities, but its application in the heavy oil recovery has not been attempted due to severe temperature challenge. We made innovations on the traditional structure of SET and got valuable results. The tubular after expansion was integrated with the original casing as a whole and the rubber was removed in-between, the wellbore size was maintained utmost and the casing was further strengthened. Meanwhile the expansion cone was put outside the tubular which is a big step forward in SET structure. Indoors experiments demonstrated sound performance of the new structure in the simulative temperature of 350 ℃, the plan for the field application was optimized based on the lessons collected in this experiment. High temperature well applications by SET were carried out in Liaohe oilfield which is famous for its heavy oil resource in China, and the detailed process as well as the outcome were compared and analyzed, finally the conclusions were drawn as a result of the whole study. We expect our work will help expand this enabling technology to better facilitate the enhancement of heavy oil recovery and maintain solid well integrity during the heavy oil production. Key words : Solid expandable tubular; Heavy oil recovery; China

99/02437 Recent development of enhanced oil recovery in China

Studies have been done in order to treat alkali scale related problems encountered in the alkali/surfactant/polymer (ASP) flooding pilot area of Daqing Oilfield. The interfacial tensions (IFT) of ASP solutions are tested using TX-500 type interfacial tensimeter (made in the USA). The effect of alkalis and surfactants on the viscoelasticity of ASP solutions are studied using HAAK RS-150H type rheometer (made in Germany). Macro-coreflood tests are performed using natural cores, 2-D vertically-heterogeneous artificial cores without restraining barriers, and 2-D vertically-heterogeneous artificial cores with restraining barriers. Blind ends' residual oil sweeping tests are performed with simplified blind-end models.The studies indicate that alkali has adverse effect on the viscoelasticity of an ASP solution. A high concentration of alkali can cause the HPAM molecular chains curl up, and can form alkali scales, although it is beneficial to an ultralow IFT. Ultralow IFT has a pronounced effect on the oil recovery of a homogeneous reservoir, while the viscoelasticity of an ASP solution contributes more to the oil recovery of a heterogeneous reservoir. The stronger the homogeneity is, the greater the effect of IFT on the oil recovery; on the contrary, the stronger the heterogeneity is, the greater the effect of viscoelasticity on the oil recovery. Laboratory “co-injection and separated-layer production” experiment also shows that a reasonable (for example 0.6%) rather than too high an alkali concentration is more beneficial to starting-up layers with medium and low permeability, and washing out the residual oil in the swept layers, and a relatively high viscoelasticity is more beneficial to sweeping the residual oil in blind ends. As far as a heterogeneous reservoir is concerned, ultralow IFT is not a ‘have-to” condition for enhancing oil recovery, while the viscoelasticity of an ASP solution is more important to effectively sweeping oil.The capillary number theory is of great practical importance for homogeneous reservoirs, but it has limitations and cannot be readily applied in heterogeneous reservoirs. For example, the trend of capillary numbers versus IFTs (corresponding to different alkali concentrations), which are based on the theory, does not match with the trend of oil recovery efficiencies. Therefore, for a heterogeneous reservoir, without an ultralow IFT (for example with an IFT of 10−2 mN/m), i.e. with a reasonably lower alkali concentration, a satisfying oil recovery can still be achieved as long as the viscoelasticity is high enough. This not only can solve the problems caused by alkali scales, but also can enlarge the selecting range of surfactants and reduce the cost of ASP flooding.

Recent development of enhanced oil recovery in China

This paper gives a brief review of the present status (after 1990) of pilot and field test results of polymer flooding, Xanthan gum flooding and combined chemical flooding enhanced oil recovery (EOR) techniques, and their future in China.

The application of NMR imaging to the studies of enhanced oil recovery in China

The advantages of the application of NMR imaging to the studies of enhanched oil recovery methods that include polymer slug flooding, combination slug flooding, and thermal soaking are described.