scholarly journals Analysis of Controlling Factors at Separate Imbibition Stages for Ultra-Low-Permeability Reservoirs

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7093
Author(s):  
Hailong Dang ◽  
Hanqiao Jiang ◽  
Binchi Hou ◽  
Xiaofeng Wang ◽  
Tao Gao ◽  
...  
Keyword(s):  
Fractured Reservoirs ◽  
Influential Factors ◽  
Controlling Factors ◽  
Spontaneous Imbibition ◽  
Low Permeability ◽  
Relative Importance ◽  
Oil Viscosity ◽  
Oil Saturation ◽  
Low Permeability Reservoirs ◽  
Interfacial Characteristics

Spontaneous imbibition is an important mechanism in naturally fractured reservoirs. In our previous studies on the effect of imbibition efficiency of ultra-low permeability reservoirs, we mostly focused on the relationship between macroscopic core recovery rate and influential factors. Additionally, we also mainly focused on the factors that control the final imbibition recovery for ultra-low permeability reservoirs. Through a large number of experiments, it was found that the factors affecting imbibition are different in separate stages. However, the relative importance of those factors in different imbibition stages was hardly studied. In this work, we tested six key factors, i.e., the core length, RQI, salinity, interfacial characteristics, initial oil saturation, and oil viscosity, in natural sandstone samples from Chang 6 in the Zichang area. Based on experimental results, we divided the imbibition process into three stages (i.e., the early stage, the middle stage, and the late stage) to quantify the effects of the controlling factors. The results show that the relative importance of the controlling factors is changing during the imbibition process. The weight of importance is obtained for those factors at each stage. In addition, a comparative model is established for the dual-porosity media from Chang 6 formation. The results show that the increase of the rock size can extend the imbibition period for the early and middle stages. Moreover, the weight of importance for the initial oil saturation, interfacial characteristics, and salinity are also analyzed in three imbibition stages. This study provides theoretical support to guide water injection in ultra-low-permeability reservoirs and to understand the formation of energy supplements and oil recovery during the imbibition process.

A Novel Deliverability Equation for Shallow Layer and Low Permeability Reservoirs with Horizontal Fracture

2012 ◽  
Vol 616-618 ◽  
pp. 1000-1007
Author(s):  
Yue Yang ◽  
Xiang Fang Li ◽  
Ke Liu Wu ◽  
Jian Yang ◽  
Jun Tai Shi ◽  
...  
Keyword(s):  
Low Permeability ◽  
Oil Viscosity ◽  
Reservoir Properties ◽  
Vertical Well ◽  
Horizontal Fracture ◽  
Vertical Permeability ◽  
Shallow Layer ◽  
Fluid Properties ◽  
Fracture Distribution ◽  
Low Permeability Reservoirs

In order to predict the productivity of vertical well for shallow layer and low permeability reservoirs with horizontal fracture, based on the theory of horizontal fracture distribution and oil seepage in reservoir, establish the reservoir seepage physical model for shallow layer and low permeability reservoirs with horizontal fracture, and derive a novel deliverability equation, considering the effect of reservoir properties, fluid properties, horizontal fracture parameters and working systems. Furthermore, the equation was applied and performed sensitivity analysis to the productivity of a vertical well in Yanchang Chang 6 layer reservoir. Results show that vertical permeability, oil viscosity and the semiminor axis of horizontal fracture have more significant impact on well productivity. With real cases, it is demonstrated the established deliverability equation is simple and practical and meets the engineering accuracy requirements.

scholarly journals Study on the Influential Factors of CO2 Storage in Low Permeability Reservoir

Energies ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 344
Author(s):  
Ping Yue ◽  
Rujie Zhang ◽  
James J. Sheng ◽  
Gaoming Yu ◽  
Feng Liu
Keyword(s):  
Carbon Dioxide ◽  
Co2 Storage ◽  
Ordos Basin ◽  
Influential Factors ◽  
Low Permeability ◽  
Geological Storage ◽  
Co2 Geological Storage ◽  
Low Permeability Reservoir ◽  
Low Permeability Reservoirs ◽  
Breakthrough Pressure

As the demands of tight-oil Enhanced Oil Recovery (EOR) and the controlling of anthropogenic carbon emission have become global challenges, Carbon Capture Utilization and Sequestration (CCUS) has been recognized as an effective solution to resolve both needs. However, the influential factors of carbon dioxide (CO2) geological storage in low permeability reservoirs have not been fully studied. Based on core samples from the Huang-3 area of the Ordos Basin, the feasibility and influential factors of geological CO2 sequestration in the Huang-3 area are analyzed through caprock breakthrough tests and a CO2 storage factor experiment. The results indicate that capillary trapping is the key mechanism of the sealing effect by the caprock. With the increase of caprock permeability, the breakthrough pressure and pressure difference decreased rapidly. A good exponential relationship between caprock breakthrough pressure and permeability can be summarized. The minimum breakthrough pressure of CO2 in the caprock of the Huang-3 area is 22 MPa, and the breakthrough pressure gradient is greater than 100 MPa/m. Huang-3 area is suitable for the geological sequestration of CO2, and the risk of CO2 breakthrough in the caprock is small. At the same storage percentage, the recovery factor of crude oil in larger permeability core is higher, and the storage percentage decreases with the increase of recovery factor. It turned out that a low permeability reservoir is easier to store CO2, and the storage percentage of carbon dioxide in the miscible phase is greater than that in the immiscible phase. This study can provide empirical reference for caprock selection and safety evaluation of CO2 geological storage in low permeability reservoirs within Ordos Basin.

scholarly journals Study on the response characteristics of oil wells after deep profile control in low permeability fractured reservoirs

Open Physics ◽  
2018 ◽  
Vol 16 (1) ◽  
pp. 832-838 ◽  
Author(s):  
Lijun Lin ◽  
Wei Lin
Keyword(s):  
Fractured Reservoirs ◽  
Oil Production ◽  
Oil Wells ◽  
Low Permeability ◽  
Response Characteristics ◽  
Well Pattern ◽  
Profile Control ◽  
Deep Profile ◽  
Low Permeability Reservoirs ◽  
Oilfield Development

AbstractThe rhombus inverted nine-spot well pattern is often adopted in low permeability oilfield development, which has the advantage of high oil production rate and flexible adjustment. Due to the strong heterogeneity of the low permeability reservoirs, the oil wells along the fracture direction are heavily water-flooded and the water cut rises quickly, and the oil wells on both sides of fractures have no response to water injection. Hence, deep profile control is an effective way to solve this kind of plane contradiction, and is widely applied in the low permeability oilfield development. However, because of the asymmetry of the rhombus inverted nine-spot well pattern and the heterogeneity of the low permeability reservoirs, there are differences in the response characteristics of oil wells at different locations after deep profile control. In this paper, combined with physical experiments and numerical simulations, we analyzed oil increment, the distribution of streamlines and slugs of wells at different locations before and after deep profile control, and evaluated the response characteristics of oil wells of rhombus inverted nine-spot well pattern after deep profile control in low permeability fractured reservoirs. It is concluded that the effect of increasing oil production of the side wells is better than that of the angle wells after deep profile control, and the response sequence is side well, angle well in short axis, and angle well in long axis, which is also verified by the practical results of deep profile control in Daqing Oilfield.

Analysis of Factors Affecting Productivity of Chang 4+5 Ultra-Low Permeability Reservoirs in Jiyuan Area

2013 ◽  
Vol 318 ◽  
pp. 419-422
Author(s):  
Qi Zhou ◽  
Yan Yi Yin
Keyword(s):  
Pressure Difference ◽  
Comprehensive Evaluation ◽  
Low Permeability ◽  
Production Test ◽  
Oil Viscosity ◽  
Factors Affecting ◽  
Early Evaluation ◽  
Oil Productivity ◽  
Productivity Prediction ◽  
Low Permeability Reservoirs

Productivity prediction is a technology for comprehensive evaluation of reservoir's oil-producing capacity, having important significance for early evaluation of oilfield and formulation of oilfield development plan. The percolation mechanism for ultra low permeability reservoirs is extremely complex, making productivity prediction difficult. The factors affecting oil productivity including reservoir parameters, production pressure difference and fluid property have been analyzed according to Chang 4+5 reservoir and production test data in Jiyuan area. Reservoir parameters have complex impact on oil productivity in production test: thickness of oil-bearing interval, electric resistivity, porosity, permeability and other factors all affect productivity in production test. The productivity in production test increases along with increase of production pressure difference under various thicknesses. The productivity is reduced with increase of crude oil viscosity. Reservoir parameter combination through comprehensive analysis is well related to productivity in production test, enabling the building of a regional productivity prediction model.

Distribution Characteristics of Fractures in the Ultra-Low Permeability Reservoirs of Anpeng Oilfield, China

2014 ◽  
Vol 909 ◽  
pp. 463-466
Author(s):  
Lei Gong ◽  
Shu Jun Guo ◽  
Shuai Gao ◽  
Xian Xian Tao ◽  
Jian Guo Huang
Keyword(s):  
Tectonic Stress ◽  
Controlling Factors ◽  
Low Permeability ◽  
Distribution Characteristics ◽  
Thin Sections ◽  
Main Fracture ◽  
Main Factors ◽  
Dip Angle ◽  
Fracture Distribution ◽  
Low Permeability Reservoirs

Using the data of cores, outcrops, thin sections and image logs, we analyzed the fracture distribution characteristics in the ultra-low permeability reservoirs of Anpeng oilfield. Then, we analyzed the main factors controlling the development of fractures. There are tectonic fractures and diagenetic fractures in the ultra-low permeability reservoirs. Tectonic fractures with high dip-angle are the main fracture type. Under the stresses resulting from horizontal tectonic compressions in the Early and Late Himalayan movements, three sets of tectonic fractures formed in the study area, i.e. E-W, NE-SW and NW-SE orientations. The E-W oriented fractures are developed better, then the NE-SW and NW-SE oriented fractures. The formation and distribution of these tectonic fractures are controlled by the tectonic stress field, lithology, porosity, permeability, layer thickness and structures. Under the same controlling factors, the origin types, occurrences and development characteristics of fractures in shallow-to mid-depth reservoirs are similar to that in the deep reservoirs. But fractures developed better in the deep reservoirs than that in the shallow-to mid-depth reservoirs.

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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