One of the feasibilities of oil recovery increase in embedded-inhomogeneous reservoir

2020 ◽  
pp. 20-26
Author(s):  
E.V. Gorshkova ◽  
◽  
E.N. Mamalov ◽  
Keyword(s):  
Oil Recovery ◽  
Natural Water ◽  
High Efficiency ◽  
Recovery Factor ◽  
Low Permeability ◽  
Combined Method ◽  
Reservoir Model ◽  
Oil Displacement ◽  
Displacement Front ◽  
Chemical Agents

The paper reviews the feasibility of oil recovery increase in embedded-ingomogeneous reservoir with hydrodynamically isolated layers of various permeability applying chemical agents. As the chemical agents, electrical-chemical modified natural water (catolyte) and catolyte-based polyacrylamide agent (PAA) are used. For oil recovery increase of the inhomogeneous reservoirs, an ecologically safe catolyte with all the properties characteristic for the alkali is applied. For the alignment of displacement front in the layers of different permeability and the flooding decrease of high-permeable reservoir, the polyacrylamide is used. This combined method was previously conducted in homogenous model and showed high efficiency. It allowed testing the method of oil displacement in embedded-ingomogeneous reservoir model. The effectiveness is achieved using catolyte and catoly- te-based PAA solutions in embedded-inhomogeneous reservoir in oil displacement process. Due to this, the low-permeability la-yer is much more involved into the process and the oil recovery factor increases.

scholarly journals Improving Oil Recovery of the Heterogeneous Low Permeability Reservoirs by Combination of Polymer Hydrolysis Polyacrylamide and Two Highly Biosurfactant-Producing Bacteria

2021 ◽  
Vol 14 (1) ◽  
pp. 423
Author(s):  
Shuwen Xue ◽  
Yanhong Zhao ◽  
Chunling Zhou ◽  
Guangming Zhang ◽  
Fulin Chen ◽  
...  
Keyword(s):  
Oil Recovery ◽  
Low Permeability ◽  
Bacterial Fermentation ◽  
The Core ◽  
Oil Displacement ◽  
Polymer Hydrolysis ◽  
Enhance Oil Recovery ◽  
Low Permeability Reservoirs ◽  
Microbial Flooding ◽  
Poly Acrylamide

Polymer hydrolysis polyacrylamide and microbes have been used to enhance oil recovery in many oil reservoirs. However, the application of this two-method combination was less investigated, especially in low permeability reservoirs. In this work, two bacteria, a rhamnolipid-producing Pseudomonas aeruginosa 8D and a lipopeptide-producing Bacillus subtilis S4, were used together with hydrolysis poly-acrylamide in a low permeability heterogeneous core physical model. The results showed that when the two bacterial fermentation liquids were used at a ratio by volumeof 1:3 (v:v), the mixture showed the optimal physicochemical properties for oil-displacement. In addition, the mixture was stable under the conditions of various temperature (20–70 °C) and salinity (0–22%). When the polymer and bacteria were mixed together, it had no significant effects in the viscosity of polymer hydrolysis polyacrylamide and the viability of bacteria. The core oil-displacement test displayed that polymer hydrolysis polyacrylamide addition followed by the bacterial mixture injection could significantly enhance oil recovery. The recovery rate was increased by 15.01% and 10.03%, respectively, compared with the sole polymer hydrolysis polyacrylamide flooding and microbial flooding. Taken together, these results suggest that the strategy of polymer hydrolysis poly-acrylamide addition followed by microbial flooding is beneficial for improving oil recovery in heterogeneous low permeability reservoirs.

scholarly journals The efficiency of gas injection into low-permeability multilayer hydrocarbon reservoirs

2021 ◽  
Vol 3 (10) ◽  
pp. 100-108
Author(s):  
Sudad H AL-Obaidi ◽  
Miel Hofmann ◽  
Falah H. Khalaf ◽  
Hiba H. Alwan
Keyword(s):  
Hydraulic Fracturing ◽  
Oil Recovery ◽  
Gas Injection ◽  
Oil Production ◽  
Recovery Factor ◽  
Low Permeability ◽  
Compositional Model ◽  
Multistage Hydraulic Fracturing ◽  
Low Permeability Reservoirs ◽  
Working Agent

The efficiency of gas injection for developing terrigenous deposits within a multilayer producing object is investigated in this article. According to the results of measurements of the 3D hydrodynamic compositional model, an assessment of the oil recovery factor was made. In the studied conditions, re-injection of the associated gas was found to be the most technologically efficient working agent. The factors contributing to the inefficacy of traditional methods of stimulating oil production such as multistage hydraulic fracturing when used to develop low-permeability reservoirs have been analyzed. The factors contributing to the inefficiency of traditional oil-production stimulation methods, such as multistage hydraulic fracturing, have been analysed when they are applied to low-permeability reservoirs. The use of a gas of various compositions is found to be more effective as a working agent for reservoirs with permeability less than 0.005 µm2. Ultimately, the selection of an agent for injection into the reservoir should be driven by the criteria that allow assessing the applicability of the method under specific geological and physical conditions. In multilayer production objects, gas injection efficiency is influenced by a number of factors, in addition to displacement, including the ratio of gas volumes, the degree to which pressure is maintained in each reservoir, as well as how the well is operated. With the increase in production rate from 60 to 90 m3 / day during the re-injection of produced hydrocarbon gas, this study found that the oil recovery factor increased from 0.190 to 0.229. The further increase in flow rate to 150 m3 / day, however, led to a faster gas breakthrough, a decrease in the amount of oil produced, and a decrease in the oil recovery factor to 0.19 Based on the results of the research, methods for stimulating the formation of low-permeability reservoirs were ranked based on their efficacy.

Efficient Displacement of Heavy Oil by Use of Three Hydrocarbon Phases

SPE Journal ◽  
2014 ◽  
Vol 19 (05) ◽  
pp. 956-973 ◽  
Author(s):  
R.. Okuno ◽  
Z.. Xu
Keyword(s):  
Phase Behavior ◽  
Oil Recovery ◽  
Heavy Oil ◽  
High Efficiency ◽  
Displacement Efficiency ◽  
The West ◽  
Optimum Pressure ◽  
Local Displacement ◽  
Oil Displacement ◽  
Three Phases

Summary Mixtures of oil with solvent gas can exhibit three-hydrocarbon-phase behavior at reservoir conditions, where the solvent-rich liquid (L2) phase coexists with the gaseous (V) and oleic (L1) phases. Three-hydrocarbon-phase behavior has been studied in the literature for carbon dioxide (CO2) floods and enriched-gas floods at relatively low temperatures. Prior research on heavy-oil displacement with enriched gas presented that displacement efficiency at a given throughput can be nonmonotonic with respect to gas enrichment. Slimtube experiments for such displacements showed that oil recovery increased first, then decreased, and increased again with increasing gas enrichment. An optimum displacement with a high efficiency of more than 90% was observed when three-hydrocarbon-phase flow was present. However, detailed mechanisms for such an optimum displacement with three phases have not been explained in the literature. In this research, we investigate mass transfer on multiphase transitions between two and three phases for three-hydrocarbon-phase displacements. Simple conditions are derived for the multiphase transitions that yield high local displacement efficiency by three hydrocarbon phases. The derivation is based on the generalized mass conservation for a multiphase transition in 1D gas injection. The conditions derived are applied to explain nonmonotonic oil recovery in quaternary displacements and the West Sak oil displacements. Oil recovery at a given throughput can be nonmonotonic with respect to pressure or gas enrichment. Such a nonmonotonic trend can occur when local oil displacement by three hydrocarbon phases becomes more efficient, but slower, with decreasing pressure or decreasing gas enrichment. An optimum pressure or enrichment can occur as a consequence of the balance between the local displacement efficiency and the propagation rate of three hydrocarbon phases. The West Sak oil displacement with enriched gas studied in this research yields a high displacement efficiency of more than 90% at 1.5 hydrocarbon pore volumes (PV) injected at 53% methane (C1) dilution.

scholarly journals Effect evaluation and influencing factors of stratified water injection in low permeability reservoir

2021 ◽  
Vol 292 ◽  
pp. 01014
Author(s):  
Xin Bai ◽  
Shiyan Hao ◽  
Chunfen Guo ◽  
Shenglin Yao
Keyword(s):  
Influencing Factors ◽  
Oil Recovery ◽  
High Efficiency ◽  
Water Injection ◽  
Low Permeability ◽  
Injection Timing ◽  
Effect Evaluation ◽  
Low Permeability Reservoir ◽  
Drive Control ◽  
Injection Effect

The main production layers in Danba oil area of Yanchang oilfield are Chang 4 + 5 and Chang 6 oil layers, which are the main development areas for increasing reserves and production. In view of the unclear influencing factors of water injection effect and the disunity of effect evaluation in the study area, the stratified water injection effect evaluation and influencing factors of low permeability reservoir are studied by means of production data statistical analysis and numerical simulation. The results show that the effect of water injection in the study area is affected by five factors: intraformational heterogeneity, interlayer heterogeneity, interlayer pressure difference, fracture and water injection timing, the results show that the water injection effect is obvious in the study area by using the five indexes of water drive reserves producing degree, water storage rate, water drive index, oil recovery rate and water drive control degree. The research results provide ideas for the study of high-efficiency separate layer water injection in low permeability reservoir, and provide guidance for the next step of potential mining.

Mechanisms of Nanofluid Based Modification MoS2 Nanosheet for Enhanced Oil Recovery

2021 ◽  
Author(s):  
M. Qu
Keyword(s):  
Physicochemical Properties ◽  
Enhanced Oil Recovery ◽  
Oil Recovery ◽  
High Efficiency ◽  
Emulsion Stability ◽  
Displacement Efficiency ◽  
Mos2 Nanosheets ◽  
Low Concentration ◽  
Oil Displacement ◽  
Oil Displacement Efficiency

Recently, much attention has been directed towards the applications of nanofluids for enhanced oil recovery (EOR). Here, amphiphilic molybdenum disulfide (KH550-MoS2) nanosheets were synthesized using a hydrothermal approach. The physicochemical properties and potential EOR of ultra-low concentration KH550-MoS2 nanofluids were systematically investigated under reservoir conditions at Changqing Oilfield (China) (temperature~55℃ and salinity~7.8×104 mg/L). Interfacial tension (IFT), wettability change, and emulsion stability were measured to evaluate the physicochemical properties of the KH550-MoS2 nanofluids. The results showed that ultra-low concentration of KH550-MoS2 nanofluid (50 mg/L) could decrease IFT to 2.6 mN/m, change the contact angle (CTA) from 131.2° to 51.7° and significantly enhance emulsion stability. Core flooding experiments were conducted to determine the dynamic adsorption loss law and the oil displacement efficiency of KH550-MoS2 nanofluid. The results indicated that the ratio of cumulative produced KH550-MoS2 nanosheets to the total injected KH550-MoS2 nanosheets (CNR) reached 91.5% during flooding in low permeability reservoirs. Moreover, ultra-low concentration KH550-MoS2 nanofluid can increase the oil displacement efficiency by 14% after water driven. This study shows the physicochemical properties of the KH550-MoS2 amphiphilic nanofluid and offers a novel high- efficiency amphiphilic nanofluid for EOR

The Simulation and Pilot Application of Low Salinity Water Flooding for Offshore Low Permeability Reservoir

2021 ◽  
Author(s):  
Hongfu Shi ◽  
Yingxian Liu ◽  
Yifan He ◽  
Wankun Xu
Keyword(s):  
Oil Recovery ◽  
Production Performance ◽  
Recovery Factor ◽  
Water Flooding ◽  
Low Permeability ◽  
Throat Radius ◽  
Low Permeability Reservoir ◽  
Low Salinity ◽  
Low Salinity Water ◽  
Salinity Water

Abstract The use of LSWF (Low Salinity Water Flooding) is becoming more prevalent in recent years which can both improve the recovery factor and reduce the cost compared to other EOR (enhanced oil recovery) technics. This is especially important for the offshore oilfield development at present. Moreover, good quality of injected water is more applicable to low permeability sand which is characterized as smaller pore-throat radius and is easier damaged. Therefore, LSWF technology is proposed to address the above production problem while reduce the investment of equipment upgrade. In this paper, we presented the optimization and implementation of LSWF for offshore low permeability reservoir. Firstly, we provided a critical review of LSWF included the main mechanisms, laboratory test and field effect. Secondly, we designed and conducted several laboratory core flood tests. Thirdly, a lot of synthetic models were established to simulate the effects of LSWF and to optimize the field program. Finally, the production performance of the pilot wells was discussed. After LSWF, the water injection well presents the phenomenon of "scissors" - the injection pressure drops significantly below the safety pressure while the injection volume increases. Moreover, the decline of pilot well groups decreased by 20% ~ 26% compared with non-water flooded. The estimated recovery factor increased by 12%, which is consistent with other field tests worldwide. In summary, LSWF is a feasible, neconomic and efficient method for offshore low permeability reservoir production.

Novel Application of Cationic Surfactants for Foams With Wettability Alteration in Oil-Wet Low-Permeability Carbonate Rocks

SPE Journal ◽  
2018 ◽  
Vol 23 (06) ◽  
pp. 2218-2231 ◽  
Author(s):  
Pinaki Ghosh ◽  
Kishore K. Mohanty
Keyword(s):  
Oil Recovery ◽  
Carbonate Rocks ◽  
Foam Stability ◽  
Wettability Alteration ◽  
Low Permeability ◽  
Zwitterionic Surfactants ◽  
Oil Displacement ◽  
Tertiary Oil Recovery ◽  
Carbonate Cores ◽  
Displacement Experiments

Summary Carbonate rocks are typically heterogeneous at many scales, leading to low waterflood recoveries. Polymers and gels cannot be injected into nonfractured low-permeability carbonates (k < 10 md) because pore throats are smaller than the polymers. Foams have the potential to improve both oil-displacement efficiency and sweep efficiency in such carbonate rocks. However, foams have to overcome two adverse conditions in carbonates: oil-wettability and low permeability. This study evaluates several cationic-foam formulations that combine wettability alteration and foaming in low-permeability oil-wet carbonate cores. Contact-angle experiments were performed on initially oil-wet media to evaluate the wettability-altering capabilities of the surfactant formulations. Static foam-stability tests were conducted to evaluate their foaming performance in bulk; foam-flow experiments (without crude oil) were performed in porous media to estimate the foam strength. Finally, oil-displacement experiments were performed with a crude oil after a secondary gasflood. Two different injection strategies were studied in this work: surfactant slug followed by gas injection and coinjection of surfactant with gas at a constant foam quality. Systematic study of oil-displacement experiments in porous media showed the importance of wettability alteration in increasing tertiary oil recovery for oil-wet media. Several blends of cationic, nonionic, and zwitterionic surfactants were used in the experiments. In-house-developed Gemini cationic surfactant GC 580 was able to alter the wettability from oil-wet to water-wet and also formed strong bulk foam. Static foam tests showed an increase in bulk foam stability with the addition of zwitterionic surfactants to GC 580. Oil-displacement experiments in oil-wet carbonate cores revealed that tertiary oil recovery with injection of a wettability-altering surfactant and foam can recover a significant amount of oil [approximately 25 to 52% original oil in place (OOIP)] over the secondary gasflood. The foam rheology in the presence of oil suggested propagation of only weak foam in oil-wet low-permeability carbonate cores.

CO2 Waterless Fracturing and Huff and Puff in Tight Oil Reservoir

2021 ◽  
Author(s):  
Weixiang Cui ◽  
Li Chen ◽  
Chunpeng Wang ◽  
Xiwen Zhang ◽  
Chao Wang
Keyword(s):  
Energy Storage ◽  
Oil Recovery ◽  
Low Permeability ◽  
Oil Viscosity ◽  
Integrated Development ◽  
Oil Displacement ◽  
Reservoir Volume ◽  
Water Based ◽  
Development Technology ◽  
Tight Reservoirs

Abstract CO2 fracturing technique is a kind of ideal waterless stimulation tech. It has the advantages of water free, low reservoir damage, and production increase by improving the reservoir pressure. At the same time, combined with reasonable shut-in control after fracturing, it can be realized integrated development technology of energy storage -fracturing and oil displacement with CO2 waterless stimulation. For low-grade and low-permeability tight reservoirs, through the integration technology of CO2 fracturing and CO2 flooding, fracture-type "artificial permeability" is formed in the formation, and micro-nano pore throat of underground matrix is formed as oil and gas production system, which realizes the development of artificial energy, reduces carbon emissions, effectively improves the productivity of low-permeability and tight reservoirs, thus further improves oil recovery. The technology mainly includes two aspects: vertical wells adopt CO2 fracturing + huff and puff displacement integration technology, horizontal wells adopt water-based fracturing + CO2 displacement technology, and utilize the high efficiency of CO2 penetration in reservoirs and crude oil viscosity reduction, which can greatly improve oil recovery, while achieving large-scale CO2 storage and reducing carbon emissions. It is both realistic and economic, and has great social benefits. The integrated development technology of energy storage -fracturing and oil displacement with CO2 waterless stimulation has been applied for 10 wells in oilfield, which has achieved good results in increasing reservoir volume, increasing formation energy, reducing oil viscosity and enhancing post-pressure recovery. As a result, the production of them has increased by over 100%. With low viscosity and high diffusion coefficient, supercritical CO2 is good for improving fracturing volume. Effective CO2 fracturing technology can improve stimulated reservoir volume, downhole monitoring results show that the cracks formed by CO2 fracturing is 3 times the size of those formed by water-based fracturing.

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