scholarly journals Study on mechanism of spontaneous imbibition and pressurized imbibition in shale oil reservoirs

2020 ◽  
Author(s):  
Lanlan Yao ◽  
Zhengming Yang ◽  
Haibo Li ◽  
Bo Cai ◽  
Chunming He ◽  
...  
Keyword(s):  
Oil Recovery ◽  
Spontaneous Imbibition ◽  
Oil Reservoirs ◽  
Recovery Ratio ◽  
Shale Oil ◽  
Fracture System ◽  
Matrix System ◽  
Jianghan Basin ◽  
Shale Oil Reservoirs ◽  
Shale Permeability

AbstractImbibition is one of the important methods of oil recovery in shale oil reservoirs. At present, more in-depth studies have been carried out on the fracture system and matrix system, and there are few studies on the effect of energy enhancement on imbibition in shale oil reservoirs. Therefore, based on the study of pressurized imbibition and spontaneous imbibition of shale oil reservoirs in Qianjiang Sag, Jianghan Basin, nuclear magnetic resonance technology was used to quantitatively characterize the production degree of shale and pore recovery contribution under different imbibition modes, and analyze the imbibition mechanism of shale oil reservoirs under the condition of energy enhancement. The experimental results showed that with the increase in shale permeability, the recovery ratio of pressurized imbibition also increased. The rate of pressurized imbibition was higher than spontaneous imbibition, and pressurized imbibition can increase the recovery ratio of fractured shale. Spontaneous imbibition can improve the ultimate recovery ratio of matrix shale. Pressurized imbibition can increase the recovery contribution of macroporous and mesoporous.

scholarly journals The effects of ion diffusion on imbibition oil recovery in salt-rich shale oil reservoirs

2019 ◽  
Vol 16 (3) ◽  
pp. 525-540 ◽  
Author(s):  
Liu Yang ◽  
Xuhui Zhang ◽  
Tong Zhou ◽  
Xiaobing Lu ◽  
Chuanqing Zhang ◽  
...  
Keyword(s):  
Oil Recovery ◽  
Oil Reservoirs ◽  
Shale Oil ◽  
Ion Diffusion ◽  
Shale Oil Reservoirs

Characteristics of shale oil reservoirs in Qianjiang Formation, Qiangjiang Depression, Jianghan Basin, China

2020 ◽  
Author(s):  
Jing Luo ◽  
Furong Wang
Keyword(s):  
Pore Volume ◽  
Salt Lake ◽  
Nitrogen Adsorption ◽  
Oil Reservoirs ◽  
Oil Reservoir ◽  
Shale Oil ◽  
Type Ii ◽  
Salt Rock ◽  
Jianghan Basin ◽  
Shale Oil Reservoirs

<p>The Jianghan Basin is a typical eastern fault depression salt lake basin in China, in which the Paleogene strata of the Qianjiang Sag are rich in shale oil resources. As a salt lake sedimentary basin, the developed Qianjiang Formation is a set of inter-salt oil-bearing strata, in which the salt rock strata are especially developed. There are many salt rhythms in the study area and a salt rhythm consists of a argillaceous dolomite layer between a salt rock formation and a salt rock formation. This study focuses on the 10th rhythm of the Qian 3<sup>4</sup> section of Qianjiang Depression (Eq3<sup>4</sup>10). The samples were investigated by organic geochemical analysis and X-ray diffraction, and the pore structure characteristics of the reservoir were studied by argon ion polishing scanning electron microscope and low temperature nitrogen adsorption test. The research indicates that the average TOC of Eq3<sup>4</sup>10 in Qianjiang Depression is 2.11% and the main distribution is 1%~3%; the type of organic matter is mainly Type II<sub>2</sub> and Type II<sub>1</sub>; the overall maturity of organic matter is low maturity stage(Tmax is 412~441℃with an average of 423℃). The XRD data indicates that the mineral composition of the Qianjiang Formation shale oil reservoir is complex and have strong heterogeneity(quartz content in 2.3%~18.6% with an average of 9.5%, calcite content in 6.9~43.8% with an average of 12.8%, dolomite content in 2.5%~ 61.2% with an average of 27.2%, clay mineral content in 1.0%~45.2% with an average of 20.5%, glauberite content from 7.1% to 92.7% with an average of 22.9%). The pore types of shale oil reservoirs in Qianjiang Sag are complex and diverse and mostly are intergranular pores, which are mainly developed between detrital minerals or between detrital minerals and carbonate minerals. In carbonate mineral particles and quartz particles, some intragranular pores are visible, including calcite dissolution pores, internal pores of calcite and clay minerals, and internal pores of pyrite particles. And organic pores are rare in reservoirs due to the low maturity(Ro ranges between 0.5% and 0.7%). Nitrogen adsorption experiments showed that the pore size distribution of Eq3<sup>4</sup>10 samples was dominated by mesopores and macropores. And the pore volume of the Eq3<sup>4</sup>10 sample was most affected by the macropore pore volume, averaging 66.22%, followed by the mesopore pore volume with an average of 31.45%. To study and understand the characteristics of shale oil reservoir in Qianjiang Depression is conducive to mastering the regularity of shale oil enrichment and provides a basis for the exploration and development of shale oil.</p>

scholarly journals Simulation Study of Allied In-Situ Injection and Production for Enhancing Shale Oil Recovery and CO2 Emission Control

Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3961
Author(s):  
Haiyang Yu ◽  
Songchao Qi ◽  
Zhewei Chen ◽  
Shiqing Cheng ◽  
Qichao Xie ◽  
...  
Keyword(s):  
Oil Recovery ◽  
Co2 Emission ◽  
Gas Injection ◽  
Water Injection ◽  
Oil Production ◽  
Injection Rate ◽  
Oil Reservoirs ◽  
Shale Oil ◽  
Shale Oil Reservoirs

The global greenhouse effect makes carbon dioxide (CO2) emission reduction an important task for the world, however, CO2 can be used as injected fluid to develop shale oil reservoirs. Conventional water injection and gas injection methods cannot achieve desired development results for shale oil reservoirs. Poor injection capacity exists in water injection development, while the time of gas breakthrough is early and gas channeling is serious for gas injection development. These problems will lead to insufficient formation energy supplement, rapid energy depletion, and low ultimate recovery. Gas injection huff and puff (huff-n-puff), as another improved method, is applied to develop shale oil reservoirs. However, the shortcomings of huff-n-puff are the low sweep efficiency and poor performance for the late development of oilfields. Therefore, this paper adopts firstly the method of Allied In-Situ Injection and Production (AIIP) combined with CO2 huff-n-puff to develop shale oil reservoirs. Based on the data of Shengli Oilfield, a dual-porosity and dual-permeability model in reservoir-scale is established. Compared with traditional CO2 huff-n-puff and depletion method, the cumulative oil production of AIIP combined with CO2 huff-n-puff increases by 13,077 and 17,450 m3 respectively, indicating that this method has a good application prospect. Sensitivity analyses are further conducted, including injection volume, injection rate, soaking time, fracture half-length, and fracture spacing. The results indicate that injection volume, not injection rate, is the important factor affecting the performance. With the increment of fracture half-length and the decrement of fracture spacing, the cumulative oil production of the single well increases, but the incremental rate slows down gradually. With the increment of soaking time, cumulative oil production increases first and then decreases. These parameters have a relatively suitable value, which makes the performance better. This new method can not only enhance shale oil recovery, but also can be used for CO2 emission control.

The Study on Oil Recovery of Matrix System in Fractured Bottom-Water Oil Reservoirs

2013 ◽  
Vol 295-298 ◽  
pp. 3232-3236
Author(s):  
Guo Qing Feng ◽  
Yang Zhao
Keyword(s):  
Oil Recovery ◽  
Bottom Water ◽  
Material Balance ◽  
Water Reservoir ◽  
Oil Reservoirs ◽  
Balance Theory ◽  
Fracture System ◽  
Matrix System ◽  
Matrix Porosity

Fracture and matrix porosity are two porosity systems in fractured bottom-water reservoir. Knowing the oil recovery in matrix system provides guidance for the later development of the reservoir. Using material balance theory, and combining with Leverett function, oil recovery of matrix and fracture system are calculated respectively, and the ultimate oil recovery of matrix system is predicted.

Effect of Fracture Characteristics on Behavior of Fractured Shale-Oil Reservoirs by Cyclic Gas Injection

2016 ◽  
Vol 19 (02) ◽  
pp. 350-355 ◽  
Author(s):  
T.. Wan ◽  
J. J. Sheng ◽  
M. Y. Soliman ◽  
Y.. Zhang
Keyword(s):  
Oil Recovery ◽  
Gas Injection ◽  
Fracture Network ◽  
Production Performance ◽  
Oil Reservoirs ◽  
Shale Oil ◽  
Well Production ◽  
The Matrix ◽  
Stress Dependent ◽  
Shale Oil Reservoirs

Summary The current technique to produce shale oil is to use horizontal wells with multistage stimulation. However, the primary oil-recovery factor is only a few percent. The low oil recovery and abundance of shale reservoirs provide a huge potential for enhanced oil-recovery (EOR) process. Well productivity in shale oil-and-gas reservoirs primarily depends on the size of fracture network and the stimulated reservoir volume (SRV) that provides highly conductive conduits to communicate the matrix with the wellbore. The fracture complexity is critical to the well-production performance, and it also provides an avenue for injected fluids to displace the trapped oil. However, the disadvantage of gasflooding in fractured reservoirs is that injected fluids may break through to production wells by means of the fracture network. Therefore, a preferred method is to use cyclic gas injection to overcome this problem. In this paper, we use a numerical-simulation approach to evaluate the EOR potential in fractured shale-oil reservoirs by cyclic gas injection. Simulation results indicate that the stimulated fracture network contributes significantly to the well productivity by means of its large contact area with the matrix, which prominently enhances the macroscopic sweep efficiency in secondary cyclic gas injection. In our previous simulation work, the EOR potential was evaluated in hydraulic planar-traverse fractures without considering the propagation of a natural-fracture network. In this paper, we examine the effect of fracture networks on shale oilwell secondary-production performance. The impact of fracture spacing and stress-dependent fracture conductivity on the ultimate oil recovery is investigated. The results presented in this paper demonstrate that cyclic gas injection has EOR potential in shale-oil reservoirs. This paper focuses on evaluating the effect of fracture spacing, the size of the fracture network, fracture connectivity (uniform and nonuniform), and stress-dependent fracture-network conductivity on well-production performance of shale-oil reservoirs by secondary cyclic gas injection.

Experimental and Numerical Study on CO2 Sweep Volume during CO2 Huff-n-Puff Enhanced Oil Recovery Process in Shale Oil Reservoirs

2019 ◽  
Vol 33 (5) ◽  
pp. 4017-4032 ◽  
Author(s):  
Lei Li ◽  
Yuliang Su ◽  
James J. Sheng ◽  
Yongmao Hao ◽  
Wendong Wang ◽  
...  
Keyword(s):  
Enhanced Oil Recovery ◽  
Oil Recovery ◽  
Numerical Study ◽  
Recovery Process ◽  
Oil Reservoirs ◽  
Shale Oil ◽  
Shale Oil Reservoirs
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