Simulation and Optimization of CO2 Huff-n-Puff Processes in Tight Oil Reservoir: A Case Study of Chang-7 Tight Oil Reservoirs in Ordos Basin

2018 ◽  
Author(s):  
Zhengdong Lei ◽  
Shuhong Wu ◽  
Tao Yu ◽  
Yi Ping ◽  
He Qin ◽  
...  
Keyword(s):  
Ordos Basin ◽  
Oil Reservoirs ◽  
Tight Oil ◽  
Oil Reservoir ◽  
Simulation And Optimization ◽  
Tight Oil Reservoir ◽  
Tight Oil Reservoirs

Characteristics and origin of the pore structure of the lacustrine tight oil reservoir in the northwestern Jiuquan Basin, China

2019 ◽  
Vol 7 (3) ◽  
pp. T625-T636
Author(s):  
Chunyan Fan ◽  
Xianglu Tang ◽  
Yuanyin Zhang ◽  
Yan Song ◽  
Zhenxue Jiang ◽  
...  
Keyword(s):  
Pore Structure ◽  
Oil Reservoirs ◽  
Tight Oil ◽  
Oil Reservoir ◽  
Type I ◽  
Thin Sections ◽  
Tectonic Events ◽  
Tight Oil Reservoir ◽  
Tight Oil Reservoirs ◽  
Intercrystalline Pores

The pore structure controls the formation processes of tight oil reservoirs. It is meaningful to study the characteristics and origin of the pore structure of the tight oil reservoir. We have analyzed the pore structure of the tight oil reservoir by thin sections, scanning electron microscopy, and mercury intrusion porosimetry. We analyze the origin of the pore structure based on sedimentological, diagenetic, and tectonism processes. The porosity of the tight oil reservoirs is mainly approximately 2%–10%, and the permeability is mainly from 0.01 to 0.3 mD. The pores of the lacustrine tight oil reservoir can be classified into the primary pore and the secondary pore. The main pores are matrix micropores and clay intercrystalline pores, as well as a few dissolved pores. However, the primary residual intergranular pore has almost disappeared, leading to a poor connectivity with a general size between 20 and 50 μm. The pore throat is divided into three categories (type I, type II, and type III) according to the porosity, permeability, and throat size and distribution. We determine that the pore structure of the lacustrine tight oil reservoir is related to sedimentary, diagenetic processes, and later tectonic events. The compaction and cementation are the main factors, whereas the dissolution and tectonic events have minor effects.

New Method Research of Tight Oil Reservoir Pulse Decay Permeability Measurement

2014 ◽  
Vol 1010-1012 ◽  
pp. 1768-1771
Author(s):  
Hai Yang Qu ◽  
Zheng Ming Yang ◽  
Ting Hu
Keyword(s):  
Steady State ◽  
Oil Reservoirs ◽  
New Method ◽  
Test Accuracy ◽  
Tight Oil ◽  
Oil Reservoir ◽  
Permeability Measurement ◽  
Good Relationship ◽  
Tight Oil Reservoir ◽  
Tight Oil Reservoirs

The permeability of tight oil reservoir is very low and general perm-plug method always has a big difference. The results can’t reach the test accuracy requirements. This paper measured 26 block rocks of Changqing tight oil reservoir and several typical tight oil reservoirs in CNPC with pulse decay new method. The result shows that the pulse decay permeability measured in the new method and steady-state Klinkenberg-corrected permeability have a good relationship. We drew a figure about the porosity and steady-state Klinkenberg-corrected permeability of these tight oil reservoirs. This research offers a technical support to the tight oil reservoirs about basic data permeability measurement.

scholarly journals OVERALL PSD AND FRACTAL CHARACTERISTICS OF TIGHT OIL RESERVOIRS: A CASE STUDY OF LUCAOGOU FORMATION IN JUNGGAR BASIN, CHINA

Fractals ◽  
2019 ◽  
Vol 27 (01) ◽  
pp. 1940005 ◽  
Author(s):  
XIXIN WANG ◽  
JIAGEN HOU ◽  
YUMING LIU ◽  
PEIQIANG ZHAO ◽  
KE MA ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Pore Radius ◽  
Junggar Basin ◽  
Oil Reservoirs ◽  
Tight Oil ◽  
Oil Reservoir ◽  
Mercury Injection ◽  
Fractal Characteristics ◽  
Tight Oil Reservoir ◽  
Tight Oil Reservoirs

Lucaogou tight oil reservoir, located in the Junggar Basin, Northwest of China, is one of the typical tight oil reservoirs. Complex lithology leads to a wide pore size distribution (PSD), ranging from several nanometers to hundreds of micrometers. To better understand PSD and fractal features of Lucaogou tight oil reservoir, the experiment methods including scanning electron microscope (SEM), rate-controlled mercury injection (RMI) and pressure-controlled mercury injection (PMI) were performed on the six samples with different lithology. The results indicate that four types of pores exist in Lucaogou tight oil reservoir, including dissolution pores, clay dominated pores, microfractures and inter-granular pores. A combination of PMI and RMI was proposed to calculate the overall PSD of tight oil reservoirs, the overall pore radius of Lucaogou tight oil reservoir ranges from 3.6[Formula: see text]nm to 500[Formula: see text][Formula: see text]m. The fractal analysis was carried out based on the PMI data. Fractal dimension (Fd) values varied between 2.843 and 2.913 with a mean value of 2.88. Fd increases with a decrease of quartz content and an increase of clay mineral content. Samples from tight oil reservoirs with smaller average pore radius have stronger complexity of pore structure. Fractal dimension shows negative correlations with porosity and permeability. In addition, fractal characteristics of different tight reservoirs were compared and analyzed.

scholarly journals Tight oil reservoir production characteristics developed by CO2 huff ‘n’ puff under well pattern conditions

2022 ◽  
Author(s):  
Zhizeng Xia ◽  
Xuewu Wang ◽  
Rui Xu ◽  
Weiwei Ren
Keyword(s):  
Physical Properties ◽  
Oil Recovery ◽  
Oil Reservoirs ◽  
Injection Timing ◽  
Tight Oil ◽  
Oil Reservoir ◽  
Natural Energy ◽  
Tight Oil Reservoir ◽  
Tight Oil Reservoirs ◽  
Production Characteristics

AbstractTight oil reservoirs have poor physical properties, and the problems including rapid oil rate decline and low oil recovery degree are quite common after volume fracturing. To obtain a general understanding of tight oil reservoir production improvement by CO2 huff ‘n’ puff, the high-pressure physical properties of typical tight oil samples are measured. Combining the typical reservoir parameters, the production characteristics of the tight oil reservoir developed by the CO2 huff ‘n’ puff are numerically studied on the basis of highly fitted experimental results. The results show that: (1) during the natural depletion stage, the oil production rate decreases rapidly and the oil recovery degree is low because of the decrease in oil displacement energy and the increase in fluid seepage resistance. (2) CO2 huff ‘n’ puff can improve the development effect of tight oil reservoirs by supplementing reservoir energy and improving oil mobility, but the development effect gradually worsens with increasing cycle number. (3) The earlier the CO2 injection timing is, the better the development effect of the tight reservoir is, but the less sufficient natural energy utilization is. When carrying out CO2 stimulation, full use should be made of the natural energy, and the appropriate injection timing should be determined by comprehensively considering the formation-saturation pressure difference and oil production rate. The research results are helpful for strengthening the understanding of the production characteristics of tight oil reservoirs developed by CO2 huff ‘n’ puff.

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