Experiment and Simulation of Gas Channeling Control Technique During CO Flooding in Normal Pressure Tight Oil Reservoir of South Ordos Basin

2020 ◽  
Author(s):  
Ting Xu ◽  
Yi Wei ◽  
Tao Ma
Keyword(s):  
Ordos Basin ◽  
Normal Pressure ◽  
Control Technique ◽  
Tight Oil ◽  
Oil Reservoir ◽  
Tight Oil Reservoir ◽  
Experiment And Simulation ◽  
Gas Channeling

Optimization of Gas Channel Controlling Technique During Co2 Immiscible Flooding in Normal Pressure Tight Oil Reservoir——A Case Study of Honghe Chang 8 Reservoir in South Ordos Basin

2021 ◽  
Author(s):  
Ting Xu ◽  
Yi Wei
Keyword(s):  
Large Scale ◽  
Normal Pressure ◽  
Small Scale ◽  
Tight Oil ◽  
Oil Reservoir ◽  
Co2 Flooding ◽  
Tight Reservoir ◽  
Starch Gel ◽  
Tight Oil Reservoir ◽  
Gas Channeling

Abstract Tight oil reservoir is commonly recognized to be difficult to supply the formation energy. Tight oil reservoir in Ordos basin is characterized to be continental sedimentation, strong heterogeneity, normal pressure (0.9), low reserve abundance, imperative to supply the displacing energy. CO2 have good injection and high displacing efficiency for extra-low permeability reservoir, which provides the reference for exploring the effective development mode in tight reservoir. Influencing by complex fracture and hydraulic fracturing, as CO2 flooding is conducted in tight oil reservoir, gas channeling phenomenon is very serious, displacing energy is difficult to be utilized. To enlarge CO2 sweep efficiency, how we can effectively control CO2 channeling becomes the first important issue in energy supplying development of normal pressure tight reservoir. In the paper, a case of Honghe Chang 8 tight oil reservoir was carried out. Medium-large and medium-small scale fractures were artificial fabricated in natural crop cores according to G&G understanding. In different fracture openings models, two-stage blocking experiments with CO2 flooding were operated with high-strength starch gel and weak-strength ethylenediamine. Slug combination, volume and sequence were evaluated and by numerical simulation, blocking strength were defined to reflect the plugging effect in the experiment. Then build up well group numerical simulation model, characterizing the complex fracture network. Blocking sites and volume of plugging agents were analyzed and optimized. Two-stage blocking technique was determined in the fracture developed tight reservoir during CO2 flooding. Research results indicate it is priority to control the gas channeling of medium-large scale fractures with sufficient volume of the starch gel. As CO2 flooding is performed, gas starts to break through, followed by small volume ethylenediamine to mitigate gas channeling. Numerical simulation shows that firstly fully controlling gas channeling from medium-large scale fracture along with principal stress, then injecting plugging agent from the injection well, being located in 1/3~1/2 of well space to treat medium-small scale fractures with the best production stimulation. Starch gel volume is determined by medium-large scale fractures pore volume(PV), while low concentration starch gel and ethylenediamine volume is optimized to be half of the medium-small scale fracture PV, in which PV of fracture permeability lower than 200×10-3μm2 determine ethylenediamine volume. Generally, plugging agent would be more than 1500m3 for a pair of I-P wells. With low cost CO2 source, CO2 flooding is expected to be one of the important development modes for normal pressure tight oil reservoir. During CO2 immiscible flooding, gas channel controlling technique plays decisive roles in ensuring successful development. Research results are not only advisable for the Ordos normal pressure tight reservoir development, but also for the similar tight reservoir in the world.

The Performance Evaluation of Old Well after SRV in Ordos Basin Tight Oil Reservoir

2014 ◽  
Author(s):  
H.. Wang ◽  
X.. Liao ◽  
H.. Ye ◽  
X.. Zhao ◽  
C.. Liao ◽  
...  
Keyword(s):  
Evaluation Method ◽  
Ordos Basin ◽  
Fracture Network ◽  
Water Flooding ◽  
Tight Oil ◽  
Oil Reservoir ◽  
Well Test ◽  
Stimulated Reservoir Volume ◽  
Tight Oil Reservoir ◽  
Volume Fracturing

Abstract The technology of Stimulated reservoir volume (SRV) has been the key technology for unconventional reservoir development, it can create fracture network in formation and increase the contact area between fracture surface and matrix, thus realizing the three-dimensional stimulation and enhancing single well productivity and ultimate recovery. In China, the Ordos Basin contains large areas of tight oil reservoir with the porosity of 2~12 % and permeability of 0.01~1 mD. The most used development mode is conventional fracturing and water flooding, which is different from the natural depletion mode in oversea, but the development effect is still unfavorable. The idea of SRV is proposed in nearly two years in Changqing Oilfield. SRV measures are implemented in some old wells in tight oil formation. It is a significant problem that should be solved urgently about how to evaluate the volume fracturing effect. Based on the real cases of old wells with SRV measures, the microseismic monitoring is used to analyze the scale of formation stimulation and the complexity of fracture network after volume fracturing; the numerical well test and production data analysis (PDA) are selected to explain the well test data, to analyze the dynamic data, and to compare the changes of formation parameters, fluid parameters and plane streamlines before and after volume fracturing; then the interpretation results of well test with the dynamic of oil and water wells are combined to evaluate the stimulation results of old wells after SRV. This paper has presented a set of screening criteria and an evaluation method of fracturing effect for old well with SRV in tight oil reservoir. It will be helpful to the selection of candidate well and volume fracturing operation in Ordos Basin tight oil reservoir. It should be noted that the evaluation method mentioned in the paper can be expanded to volume stimulation effect evaluation in other unconventional reservoirs, such as tight gas, shale gas and so on.

Development and Application of Cyclic Stress Fracturing for Tight Oil Reservoir in Ordos Basin

2019 ◽  
Author(s):  
Xiaohu Bai ◽  
Kuangsheng Zhang ◽  
Meirong Tang ◽  
Chengwang Wang ◽  
Guanggao Wang ◽  
...  
Keyword(s):  
Ordos Basin ◽  
Cyclic Stress ◽  
Tight Oil ◽  
Oil Reservoir ◽  
Tight Oil Reservoir

The Study of CO2 Flooding of Horizontal Well with SRV in Tight Oil Reservoir

2014 ◽  
Author(s):  
H.. Wang ◽  
X.. Liao ◽  
X.. Zhao ◽  
H.. Ye ◽  
X.. Dou ◽  
...  
Keyword(s):  
Horizontal Well ◽  
Ordos Basin ◽  
Gas Injection ◽  
Tight Oil ◽  
Oil Reservoir ◽  
Co2 Flooding ◽  
Vertical Wells ◽  
Injection Volume ◽  
Fractured Horizontal Well ◽  
Tight Oil Reservoir

Abstract As one kind of unconventional reservoirs, tight oil reservoir has become one of the main forces of oil reserves and production growth. The characteristics of tight oil reservoir are low porosity and ultra-low permeability, thus stimulated reservoir volume (SRV) should be conducted whether applying the mode of vertical wells or horizontal wells production. Tight oil reservoir is mostly developed by natural depletion or water flooding recently, but the problems are existed, including low recovery factor with natural depletion and the difficulty of water injection. To further improve the development effect of tight oil reservoir, CO2 flooding is proposed. Based on chang-8 tight oil reservoir in Ordos Basin, an oil sample of typical block is selected. The PVT experiments are conducted. The compositional numerical model of five-spot pattern is established with a horizontal well in the middle and 4 vertical wells on the edge. Based on the model, several CO2 flooding scenarios of horizontal well with different completion measures are studied. Furthermore, parameters such as the formation pressure, production rate, shut-in gas-oil ratio and total gas injection volume are optimized. The results of this study show that the recovery factor of horizontal well with SRV is higher than those of horizontal well and conventional fractured horizontal well. The minimum miscible pressure (MMP) and the total gas injection volume are two key factors of CO2 flooding effect. CO2 flooding of volume fractured horizontal well in tight oil reservoir can not only improve oil recovery, but also realize CO2 geological sequestration. It plays dual benefits of economy and environment. The study gives new ideas of CO2 flooding with volume fractured horizontal well for the Ordos Basin tight oil reservoir. It can be helpful for rapid and effective development of tight oil reservoirs in Ordos Basin.

Spatiotemporal variations in seismic attenuation during hydraulic fracturing: A case study in a tight oil reservoir in the Ordos Basin, China

Geophysics ◽  
2021 ◽  
pp. 1-56
Author(s):  
Han Li ◽  
Xu Chang ◽  
Xiao-Bi Xie ◽  
Yibo Wang
Keyword(s):  
Hydraulic Fracturing ◽  
Ordos Basin ◽  
Seismic Attenuation ◽  
Tight Oil ◽  
Oil Reservoir ◽  
Spatiotemporal Variations ◽  
Waveform Data ◽  
Log Data ◽  
The Ordos Basin ◽  
Tight Oil Reservoir

During hydraulic fracturing (HF) stimulation for unconventional reservoir development, seismic attenuation has a significant influence on high-frequency microseismic data. Attenuation also provides important information for characterizing reservoir structure and changes to it due to HF injections. However, the attenuation effect is typically not considered in microseismic analysis. We have adopted the spectral ratio and centroid-frequency shift methods to estimate the subsurface attenuation (the factor Q−1) in a tight oil reservoir in the Ordos Basin, China. The P- and S-wave attenuations are calculated using the 3C waveform data recorded by a single-well downhole geophone array during a 12-stage HF stimulation. Both methods provide similar results (with differences in Q−1 of absolute values less than 0.010 for P- and S-waves). For individual events, their median Q−1 values calculated from different geophones are selected to represent the average attenuation. Spatiotemporal variations in attenuation are obtained by investigating Q−1 values along propagating rays linking different source-receiver pairs. The Q−1 values derived at different HF stages reveal significant attenuation in the targeted tight sandstone layer (0.030–0.062 for Q−1P and 0.026−0.058 for Q−1S), and the attenuation is apparently increased by fluid injection activities. We explain the sudden decrease in attenuation near the geophone array as a result of high shale content using log data from a horizontal treatment well. The consistency between the Q−1 values and horizontal well-log data, as well as the HF process, indicates the reliability and robustness of the attenuation results. By studying spatiotemporal variations in attenuation, the changes in subsurface structures may be quantitatively characterized, thereby creating a reliable basis for microseismic modeling and data processing and providing additional information on monitoring the HF process.

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