Optimized Cyclic Water Injection Strategy for Oil Recovery in Low-Permeability Reservoirs

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Xiaofei Sun* ◽  
Yanyu Zhang ◽  
Jie Wu ◽  
Mengke Xie ◽  
Hang Hu
Keyword(s):  
Oil Recovery ◽  
Water Injection ◽  
Tracer Tests ◽  
Oil Prices ◽  
Fuzzy Comprehensive Evaluation ◽  
Low Permeability ◽  
Operational Parameters ◽  
Recovery Method ◽  
Low Permeability Reservoir ◽  
Low Permeability Reservoirs

With the worldwide decline in conventional oil production, tremendous unconventional resources, such as low-permeability reservoirs, are becoming increasingly important. Cyclic water injection (CWI) as an oil recovery method has attracted increasing attention in the present environment of low oil prices. However, the optimal CWI strategy is difficult to determine for a mature oilfield due to the involvement of multiple wells with multiple operational parameters. Thus, our main focus in this paper is to present a novel and systematic approach to optimize CWI strategies by studying a typical low-permeability, namely, reservoir G21. To this end, a comprehensive method that combines the advantages of streamline simulation and fuzzy comprehensive evaluation (FCE) was proposed to identify water channeling in the reservoir. Second, the reliability of the method was verified using tracer tests. Finally, a new hybrid optimization algorithm, the simulated annealing-genetic algorithm (SAGA), coupled with a reservoir simulator was developed to determine an optimal CWI strategy for the low-permeability reservoir. The results show that the CWI technique is viable as a primary means in the present environment of low oil prices to improve the waterflood performance in low-permeability reservoirs. The oil recovery of the most efficient strategy increases by 6.8% compared to conventional waterflooding. The asymmetric CWI scheme is more efficient than the symmetric CWI scheme for the low-permeability reservoir.

The Research and Evaluation of Finely Layered Water Injection Standard in Low-Permeability Reservoirs - A Case from Block A in one Low-Permeability Reservoir

2014 ◽  
Vol 1073-1076 ◽  
pp. 2310-2315 ◽  
Author(s):  
Ming Xian Wang ◽  
Wan Jing Luo ◽  
Jie Ding
Keyword(s):  
Oil Recovery ◽  
Water Injection ◽  
Injection Pressure ◽  
Injection Rate ◽  
Low Permeability ◽  
Reservoir Permeability ◽  
Engineering Parameters ◽  
The Common ◽  
Common Problems ◽  
Low Permeability Reservoirs

Due to the common problems of waterflood in low-permeability reservoirs, the reasearch of finely layered water injection is carried out. This paper established the finely layered water injection standard in low-permeability reservoirs and analysed the sensitivity of engineering parameters as well as evaluated the effect of the finely layered water injection standard in Block A with the semi-quantitative to quantitative method. The results show that: according to the finely layered water injection standard, it can be divided into three types: layered water injection between the layers, layered water injection in inner layer, layered water injection between fracture segment and no-fracture segment. Under the guidance of the standard, it sloved the problem of uneven absorption profile in Block A in some degree and could improve the oil recovery by 3.5%. The sensitivity analysis shows that good performance of finely layered water injection in Block A requires the reservoir permeability ratio should be less than 10, the perforation thickness should not exceed 10 m, the amount of layered injection layers should be less than 3, the surface injection pressure should be below 14 MPa and the injection rate shuold be controlled at about 35 m3/d.

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.

Study on CO2 Injection for Enhancing the Oil Recovery at Gao89 Block in Shengli Oilfield

2013 ◽  
Vol 734-737 ◽  
pp. 1464-1467
Author(s):  
Song Lin Shi ◽  
Jian Kang ◽  
Meng Li
Keyword(s):  
Oil Recovery ◽  
Gas Injection ◽  
Water Injection ◽  
Low Permeability ◽  
Recovery Method ◽  
Shengli Oilfield ◽  
Geological Features ◽  
Efficient Recovery ◽  
Original Production ◽  
Enhance Oil Recovery

Gao 89 Block is a low permeability oil reservoir. These reservoirs have difficulty in water injection, poor well condition, and low original production. Gas injection can solve this problem. It is the most efficient recovery method for low-permeability reservoirs at home and abroad. In accordance with the geological features and development actuality of Gao89 Block, the feasibility and optimization of gas injection are studied, the effect of gas injection on the development index and development results are demonstrated. The results indicate that the gas injection can dramatically enhance oil recovery and increase the oil production.

A Study of Seepage Characteristics of Unsteady Waterflooding Development for Fractured Ultra-Low-Permeability Reservoir

2021 ◽  
Author(s):  
Qing Liu ◽  
Xiangfang Li ◽  
Jian Yang ◽  
Sen Feng ◽  
Minxia He ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Simulation Model ◽  
Water Injection ◽  
Injection Rate ◽  
Low Permeability ◽  
Tensor Model ◽  
Capillary Imbibition ◽  
Low Permeability Reservoir ◽  
Water Cut ◽  
Low Permeability Reservoirs

Abstract Unconventional fractured ultra-low-permeability reservoirs play an important role in continental sedimentary basins in China, and their formation characteristics and seepage laws are greatly different from that of traditional reservoirs. In this paper, the influence of microfractures and unsteady waterflooding on the productivity of fractured ultra-low permeability reservoirs are studied deeply. The reservoir parameters used in the study are from an actual fractured ultra-low-permeability reservoir in Ordos Basin, where microfractures are developed but macroscopic fractures are not. The microfractures have a small opening and are widely distributed in the reservoir, so the reservoir numerical simulation model adopts the equivalent continuous matrix model to simulate waterflooding. On one hand, the physical model of micro-fractured reservoir and the permeability tensor model of the equivalent continuous matrix are established. The results show that the existence of microfractures can increase the permeability of matrix by 1.4 times. On the other hand, an ideal heterogeneous numerical simulation model composed of pure matrix and equivalent continuous matrix considering microfracture is established according to actual geological parameters of the fractured ultra-low-permeability reservoir. To simulate and compare the unsteady waterflooding and continuous waterflooding development in 10-year development under the condition of constant annual injection rate, the results indicate that unsteady waterflooding development make higher productivity and lower water cut and lower formation water saturation than that of continuous waterflooding. By conducting unsteady waterflooding development simulation for sensitivity analysis, the results demonstrate that the greater the capillary force, the better the role of capillary imbibition in a certain range, meanwhile, the unsteady waterflooding has the best exploitation effect when the value of water injection cycle time is 100 days and the fluctuation amplitude of water injection rate is 1. At the above situation, the displacement and capillary imbibition and pressure disturbance achieve the desired effect of reducing water cut and increasing oil production.

scholarly journals Mechanism of Enhanced Oil Recovery for In-Depth Profile Control and Cyclic Waterflooding in Fractured Low-Permeability Reservoirs

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Daiyin Yin ◽  
Wei Zhou
Keyword(s):  
Enhanced Oil Recovery ◽  
Depth Profile ◽  
Oil Recovery ◽  
Water Injection ◽  
High Water ◽  
Low Permeability ◽  
Profile Control ◽  
High Water Cut ◽  
Water Cut ◽  
Low Permeability Reservoirs

When fractured low-permeability reservoirs enter a high water cut period, injected water always flows along fractures, water cut speeds increase rapidly, and oil production decreases quickly in oil wells. It is difficult to further improve the oil recovery of such fractured low-permeability reservoirs. In this paper, based on the advantages of in-depth profile control and cyclic water injection, the feasibility of combining deep profile control with cyclic water injection to improve oil recovery in fractured low-permeability reservoirs during the high water cut stage was studied, and the mechanisms of in-depth profile control and cyclic waterflooding were investigated. According to the characteristics of reservoirs in Zone X, as well as the fracture features and evolution mechanisms of the well network, an outcrop plate fractured core model that considers fracture direction was developed, and core displacement experiments were carried out by using the HPAM/Cr3+ gel in-depth profile control system. The enhanced oil recovery of waterflooding, cyclic water injection, and in-depth profile control, as well as a combination of in-depth profile control and cyclic water injection, was investigated. Moreover, variations in the water cut degree, reserve recovery percentage, injection pressure, fracture and matrix pressure, and water saturation were monitored. On this basis, the mechanism of enhanced oil recovery based on the combined utilization of in-depth profile control and cyclic waterflooding methods was analyzed. The results show that in-depth profile control and cyclic water injection can be synchronized to further increase oil recovery. The recovery ratio under the combination of in-depth profile control and cyclic water injection was 1.9% higher than that under the in-depth profile control and 5.6% higher than that under cyclic water injection. The combination of in-depth profile control and cyclic water injection can increase the reservoir pressure; therefore, the fluctuation of pressure between the matrix and its fractures increases, more crude oil flows into the fracture, and the oil production increases.

A New well Pattern for Enhancing Waterflood Performance of Ultra-Low Permeability Reservoir in Changqing Oilfield

2013 ◽  
Vol 318 ◽  
pp. 501-506
Author(s):  
Zhang Zhang ◽  
Shun Li He ◽  
Hai Yong Zhang
Keyword(s):  
Oil Recovery ◽  
Early Stage ◽  
Water Injection ◽  
Field Application ◽  
Low Permeability ◽  
Great Ability ◽  
Low Permeability Reservoir ◽  
Well Spacing ◽  
Well Pattern ◽  
The One

Because the development of ultra-low permeability reservoir is relative to fracture system, suitable well pattern arrangement is very significant for effective flooding management. There were three kinds of well pattern used to waterflood in Changqing oilfield: square inverted nine-spot, rhombus inverted nine-spot and rectangular five-spot pattern, according to the degree of fracture growth. In view of the defects of these well patterns in the development of ultra-low permeability reservoirs, a new well spacing concept is developed. Numerical simulations are carried out to illustrate the adaptability and strong points of this new well pattern. For this well pattern, on the one hand, the distance between producers and injectors along the fracture direction is widened and thus massive fracturing can be conducted to enhance oil productivity and water injection, and on the other hand, a high producer/injector ratio ensures high oil recovery rate in early stage. Besides, this new well pattern has a great ability of adjustment. Field application showed a remarkably well producing performance.

Reasonably Water Injection Time about Abnormal Pressure of Low Permeability Reservoir

2012 ◽  
Vol 601 ◽  
pp. 134-138
Author(s):  
Xiao Liang Huang
Keyword(s):  
Pore Space ◽  
Water Injection ◽  
Stress Sensitivity ◽  
Reservoir Rock ◽  
Low Permeability ◽  
Injection Timing ◽  
Injection Time ◽  
Low Permeability Reservoir ◽  
Abnormal Pressure ◽  
Low Permeability Reservoirs

Abnormal pressure of low permeability reservoirs is a special reservoir, which have some characteristic : low permeability, strong stress sensitivity, complex pore structure, abnormal pressure. with the pressure decreasing about bottom-hole and reservoir, the formation of the rock pore space and permeability will decrease, and reservoir stress-sensitive phenomenon of serious. All these have brought greater difficulty for developing. in order to reasonable development of those reservoirs, maintain the formation energy is important, choose the reasonable injection timing is an important aspect. In this paper, taking abnormal pressure of low permeability reservoir as an example, studies variation law of abnormally pressure reservoir rock compressibility, porosity, stress sensitivity by experimental, Associated with the nature of the reservoir to determine a reasonable water injection time, and demonstrated by numerical simulation, finally proposed reasonable water injection timing about abnormal pressure of low-permeability reservoirs.

The Optimization of CO2 Huff and Puff Well Location in Ultra-Low Permeability Reservoir

2013 ◽  
Vol 690-693 ◽  
pp. 3086-3089
Author(s):  
Dong Feng Zhao ◽  
Xin Wei Liao ◽  
Shao Ping Wang ◽  
Dan Dan Yin ◽  
Bao Bing Shang
Keyword(s):  
Oil Recovery ◽  
Comprehensive Evaluation ◽  
Fuzzy Comprehensive Evaluation ◽  
Theoretical Research ◽  
Low Permeability ◽  
Evaluation Standard ◽  
Technological Support ◽  
Low Permeability Reservoir ◽  
Well Location ◽  
Liquid Property

The oil recovery of CO2huff and puff well in ultra-low permeability reservoir is low. It is necessary to take measures to increase the development benefit. So the relevant development examples and theoretical research are taken into account in this paper, and according to liquid property and reservoir characteristics, the screening and evaluating system and grading evaluation standard of CO2 huff and puff well location is established. Based on fuzzy comprehensive evaluation, screening steps of CO2 huff and puff well location in ultra-low permeability reservoir is also established. The effect of the method has been proved by field practice. The result provides theoretical and technological support. And it provides reference for similar reservoirs.

The Porous Medium of Ultra-Low Permeability Reservoir has an Effect on Oil Recovery

2013 ◽  
Vol 779-780 ◽  
pp. 1457-1461
Author(s):  
Xian Wen Li ◽  
Chun Mei Xu ◽  
Fang Yuan Guo ◽  
Xing Hong Wang
Keyword(s):  
Porous Medium ◽  
Oil Recovery ◽  
Research Result ◽  
Water Injection ◽  
Injection Pressure ◽  
Injection Rate ◽  
Particle Migration ◽  
Low Permeability ◽  
Reservoir Water ◽  
Low Permeability Reservoir

This paper from the research of the porous medium pore structure characteristics of ultra-low permeability reservoir, combined the core flow test with reservoir characteristics analysis and fluid properties analysis studying the reservoir water injection development effect. The research results show that: the microscopic heterogeneity of ultra-low permeability reservoir is strong, pore connectivity of porous medium is poor, seepage throat is very fine and microcrack is growth. During the process of water injection development there exist particle migration phenomenon, could easily cause pore throat blockage, and lead to water injection pressure rebound. According to the research result targeted on the organic mud acid deep broken down experiment, the result shows that it can achieve the purpose of depressure and increasing injection rate.

ASSESSMENT OF OIL WELL PRODUCTIVITY IN LOW-PERMEABILITY RESERVOIRS IN THE FIELDS OF EASTERN SIBERIA

2017 ◽  
pp. 30-36
Author(s):  
R. V. Urvantsev ◽  
S. E. Cheban
Keyword(s):  
Oil Recovery ◽  
Large Scale ◽  
Oil And Gas ◽  
Oil Extraction ◽  
Low Permeability ◽  
Oil Well ◽  
Eastern Siberia ◽  
Development Costs ◽  
Traditional Fields ◽  
Low Permeability Reservoirs

The 21st century witnessed the development of the oil extraction industry in Russia due to the intensifica- tion of its production at the existing traditional fields of Western Siberia, the Volga region and other oil-extracting regions, and due discovering new oil and gas provinces. At that time the path to the development of fields in Eastern Siberia was already paved. The large-scale discoveries of a number of fields made here in the 70s-80s of the 20th century are only being developed now. The process of development itself is rather slow in view of a number of reasons. Create a problem of high cost value of oil extraction in the region. One of the major tasks is obtaining the maximum oil recovery factor while reducing the development costs. The carbonate layer lying within the Katangsky suite is low-permeability, and its inventories are categorised as hard to recover. Now, the object is at a stage of trial development,which foregrounds researches on selecting the effective methods of oil extraction.

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