Mechanistic study of cyclic water injection to enhance oil recovery in tight reservoirs with fracture deformation hysteresis

Fuel ◽  
2020 ◽  
Vol 271 ◽  
pp. 117677 ◽  
Author(s):  
Lijun Liu ◽  
Yongzan Liu ◽  
Jun Yao ◽  
Zhaoqin Huang
Keyword(s):  
Oil Recovery ◽  
Water Injection ◽  
Mechanistic Study ◽  
Fracture Deformation ◽  
Tight Reservoirs ◽  
Enhance Oil Recovery ◽  
Deformation Hysteresis

Coupled Flow/Geomechanics Modeling of Interfracture Water Injection To Enhance Oil Recovery in Tight Reservoirs

SPE Journal ◽  
2020 ◽  
Author(s):  
Yongzan Liu ◽  
Lijun Liu ◽  
Juliana Y. Leung ◽  
Kan Wu ◽  
George Moridis
Keyword(s):  
Oil Recovery ◽  
Horizontal Well ◽  
Water Injection ◽  
Injection Rate ◽  
Natural Fracture ◽  
Tight Oil ◽  
Coupled Flow ◽  
Fracture Spacing ◽  
Tight Reservoirs ◽  
Enhance Oil Recovery

Summary Unconventional tight reservoirs that are typically characterized by low permeability and low porosity have contributed significantly to the global hydrocarbon production in recent years. Although hydraulic fracturing, along with horizontal well drilling, enables the economic development of such reservoirs, the production rate often declines sharply and results in low primary hydrocarbon recovery. The application of enhanced-oil-recovery (EOR) techniques in tight reservoirs has received much interest. In this study, the feasibility and efficiency of interfracture water injection to enhance oil recovery in multistage fractured tight oil reservoirs are analyzed through an efficient coupled flow/geomechanics model with an embedded discrete-fracture model (EDFM). A combined finite-volume/finite-element scheme is used to discretize the governing equations for flow and geomechanics, and the coupled problem is solved sequentially using a fixed-stress splitting algorithm. A basic numerical model consisting of a 15-stage fractured horizontal well is constructed using the petrophysical and geomechanical properties of a tight oil formation in Ordos Basin, China. Fractures indexed with even numbers are switched into injecting fractures when the production rate has dropped to less than a certain threshold. The improvement of oil recovery is analyzed by comparing the production profiles with and without water injection. In this coupled model, the fracture closure/opening during production/injection is considered according to the constitutive relations between fracture aperture and effective normal stress acting on the fracture faces. The poromechanical response of matrix is modeled by the Biot (1941) theory. The effects of fracture spacing, injection rate, and the presence of a natural-fracture network on oil-recovery enhancement are discussed through sensitivity analysis. The main mechanisms of interfracture water injection for enhancing oil recovery are waterflooding and reservoir-pressure maintenance. Small fracture spacing tends to reduce the oil recovery because of fracture interference and a limited drainage area; therefore, the primary depletion stage is shortened as the fracture spacing is reduced. The influence of interfracture water injection is more pronounced with smaller fracture spacing because the pressure-transient responses near the producing fractures are more dramatic considering the close proximity between the injecting fracture and the producing fracture. Although a higher injection rate results in higher oil recovery, the injectivity in low-permeability reservoirs limits the maximum-allowable injection rate. When secondary (natural)-fracture networks are considered, neighboring hydraulic fractures can be connected to one another via the secondary fractures, particularly if the interfracture spacing is small. Water can break through in the producing fractures quickly, which could also lead to high water cut and suboptimal oil-recovery performance. This study tests the feasibility and efficiency of interfracture injection to enhance tight oil recovery. The results indicate that interfracture injection can be a promising EOR technique for tight oil reservoirs, which sheds lights on future completion strategies and production design in tight reservoirs.

Reservoir Simulation Study on Air-Foam Flooding to Enhance Oil Recovery in Waterflooding Sandstone Reservoir

2014 ◽  
Vol 962-965 ◽  
pp. 461-464
Author(s):  
Ping Yuan
Keyword(s):  
Low Temperature ◽  
Oil Recovery ◽  
Water Injection ◽  
Steam Injection ◽  
Utilization Rate ◽  
Low Temperature Oxidation ◽  
Temperature Oxidation ◽  
Sandstone Reservoir ◽  
Foam Flooding ◽  
Enhance Oil Recovery

In the later waterflooding sandstone reservoir, there are many serious development contradictions, especially in the aspects of water breakthrough and heterogeneous development. Based on the laboratory experiments, numerical simulation research on historical match of the low temperature oxidation kinetics model, the injection mode, foaming agent concentration, gas to liquid ratio, steam injection rate and other key parameters of air-foam flooding were carried out. The results show that, air foam flooding technology integrated comprehensive effect of low-temperature oxidation, air flooding and foam flooding, which enhance oil recovery nearly 8% by block the thief layer effectively and improving the swept volume. Air-foam flooding technology also can reduce the amount of water injection and water production, which improved the utilization rate of water resources and reduced output liquid processing cost. This technology shows its broad prospect of application and can provide reference for similar reservoirs.

scholarly journals Experimental Investigation on Oil Enhancement Mechanism of Hot Water Injection in tight reservoirs

Open Physics ◽  
2016 ◽  
Vol 14 (1) ◽  
pp. 703-713 ◽  
Author(s):  
Hao Yongmao ◽  
Lu Mingjing ◽  
Dong Chengshun ◽  
Jia Jianpeng ◽  
Su Yuliang ◽  
...  
Keyword(s):  
Oil Recovery ◽  
Water Saturation ◽  
Water Injection ◽  
Hot Water ◽  
Water Flooding ◽  
Water Displacement ◽  
Pore Characteristics ◽  
Irreducible Water Saturation ◽  
Tight Reservoirs ◽  
Oil Water

AbstractAimed at enhancing the oil recovery of tight reservoirs, the mechanism of hot water flooding was studied in this paper. Experiments were conducted to investigate the influence of hot water injection on oil properties, and the interaction between rock and fluid, petrophysical property of the reservoirs. Results show that with the injected water temperature increasing, the oil/water viscosity ratio falls slightly in a tight reservoir which has little effect on oil recovery. Further it shows that the volume factor of oil increases significantly which can increase the formation energy and thus raise the formation pressure. At the same time, oil/water interfacial tension decreases slightly which has a positive effect on production though the reduction is not obvious. Meanwhile, the irreducible water saturation and the residual oil saturation are both reduced, the common percolation area of two phases is widened and the general shape of the curve improves. The threshold pressure gradient that crude oil starts to flow also decreases. It relates the power function to the temperature, which means it will be easier for oil production and water injection. Further the pore characteristics of reservoir rocks improves which leads to better water displacement. Based on the experimental results and influence of temperature on different aspects of hot water injection, the flow velocity expression of two-phase of oil and water after hot water injection in tight reservoirs is obtained.

scholarly journals A laboratory approach to enhance oil recovery factor in a low permeable reservoir by active carbonated water injection

2021 ◽  
Vol 7 ◽  
pp. 3149-3155
Author(s):  
Xinxiao Chen ◽  
Aminsadegh Paprouschi ◽  
Marischa Elveny ◽  
Dmitriy Podoprigora ◽  
Grigory Korobov
Keyword(s):  
Oil Recovery ◽  
Water Injection ◽  
Recovery Factor ◽  
Carbonated Water Injection ◽  
Carbonated Water ◽  
Enhance Oil Recovery

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.

Insights on Water Sources for Injection Development of Large Oilfields in Southeast Iraq and Appraisal of Paleogene Shallow Water Source Formation

2021 ◽  
Author(s):  
Guosheng Qin ◽  
Youjing Wang
Keyword(s):  
Shallow Water ◽  
Sequence Stratigraphy ◽  
Oil Recovery ◽  
Water Injection ◽  
Water Source ◽  
Water Volume ◽  
Preliminary Evaluation ◽  
Core Analysis ◽  
High Porosity ◽  
Enhance Oil Recovery

Abstract As many large oilfields in southeast Iraq entered the final stage of depletion development, water injection appears to be the most economical and technically feasible method to enhance oil recovery. Considering the shortage of freshwater and huge investment in seawater supply project, it is very important to appraise and optimize the favorable shallow water source formation to ensure sufficient water injection supply. Based on regional seismic, well data, core analysis and production test data, Paleogene sequence stratigraphy was determined by integrating well and seismic interpretation. Under framework of sequence stratigraphy, the sedimentary evolution of main water source formations was characterized. Subsequently, combined with core analysis and special logging data, the petrophysical characteristics of the formations were evaluated, and the volume of the regional water source was estimated. The research shows that: 1) Dammam limestone and Ghar sandstone are the two main Paleogene shallow water source formations; 2) Dammama developed carbonate shelf, from southwest to northeast, the formation thickness decrease with the sedimentary evolved from inner slope to out slope. Expose and dissolution increased the porosity which is favorable for water storage; 3) Ghar developed alluvial and delta, from southwest to northeast, the formation thickness increase with the sedimentary evolved from alluvial fan, alluvial river to delta. Delta developed abundant and unconsolidated sandstone with high porosity and permeability; 4) The water sample analysis showed the water belong to Cacl2 type with total dissolved solids greater than 250,000 ppm which indicated well sealing condition. Production tests have shown that both Dammam and Ghar have a water supply capacity of 8,000-10,000 barrels per day. The preliminary evaluation of the water volume in the Ghar area can up to 1 trillion barrels. Paleogene shallow water formation is currently the most realistic and economic water source choice for water injection to enhance oil recovery in large oil fields in southeastern Iraq. Dammam formation and Ghar formation of Paleogene had the characteristics of shallow buried, good water quality and sufficient reserves. Thus, they are the preferred target water source formations for injection development of large oilfields in southeastern Iraq.

scholarly journals Study on the Production Mode of Horizontal Well from Water Huff and Puff to Segmented Injection and Production in Tight Reservoir

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Shiying Di ◽  
Shiqing Cheng ◽  
Cao Wei ◽  
Wenpeng Bai ◽  
Ruyuan Shang ◽  
...  
Keyword(s):  
Dynamic Fracture ◽  
Oil Recovery ◽  
Recovery Rate ◽  
Water Injection ◽  
Fracture Network ◽  
Natural Fracture ◽  
Natural Fractures ◽  
Tight Reservoir ◽  
Tight Reservoirs ◽  
Cumulative Recovery

Water huff and puff in horizontal wells in tight reservoirs has achieved good results in replenishing formation energy. However, after multiple rounds of treatment, a rapid decrease in formation pressure takes place making it difficult to maintain stable production. To improve the oil recovery rate of tight reservoirs, it is imminent to change the development mode. In this work, the stress distribution characteristics at fracture tips were analyzed based on Irwin theory and elastic theory. A model of propagation and closure length of fractures was established based on the propagation mechanism of water injection-induced natural fracture and the energy balance principle of fracture mechanics. Surfactant imbibition experiments were carried out according to the imbibition principle of surfactant system, and the propagation law of natural fractures was described with numerical simulation to analyze the seepage characteristics of dynamic fracture network. On the basis of the above works, alternating water huff and puff into segmented injection and production was proposed according to the distribution law of dynamic fracture network. The developing process of an actual well case by these two developing modes was simulated to predict 18 years of cumulative recovery, pressure distribution, and recovery rate. Results showed that when stress intensity factor exceeds the fracture toughness, the natural fractures will extend along their original directions and get connected, forming an irregular fracture network. The lengths of fractures after propagation and closure will not bring about water channeling for they are far shorter than well and interval spacing. Surfactant could diminish the resistance of boundary layer by reducing the wetting contact angle, ending up with an improvement in imbibition efficiency. Radial displacement and dynamic imbibition occur simultaneously in a dynamic fracture network during the early stage of water injection, while static imbibition mainly occurs during injection shutdown period and well soaking. According to comparison, the swept area of segmented injection and production was larger, ending up with a continuous increase of simulated recovery rate and cumulative recovery. The findings of this study show alternating water huff and puff after to segmented injection and production in fractured tight reservoir can allow full play of dynamic fracture network’s potential and achieve effective enhancement in oil recovery rate.

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