A study on core spontaneous imbibition behavior via nuclear magnetic resonance and displacement experiments

Field observations show that less than one percent of dissociation water can be produced during gas hydrate production, resulting from spontaneous water imbibition into matrix pores. What’s more, the hydrate sediments are easily dispersed in water, and it is difficult to carry out spontaneous imbibition experiments. At present, there is little research work on the imbibition capacity of hydrate sediments. In this paper, a new method of water imbibition is proposed for hydrate sediments, and nuclear magnetic resonance (NMR) technique is used to monitor water migration. The results show that as the imbibition time increases, the water is gradually imbibed into matrix pores. Water imbibition can cause dramatic changes in pore structure, such as microfracture initiation, fracture network generation and skeleton dispersion. When the imbibition time exceeds a critical value, many secondary pores (new large pores and micro-fractures) start to appear. When imbibition time exceeds the dispersion time, fracture networks are generated, eventually leading to dispersion of the sediment skeleton. The imbibition curves of hydrate sediments can be divided into two linear stages, which corresponds, respectively, to water imbibition of primary pores and secondary pores. The imbibition rate of secondary pores is significantly larger than that of primary pores, indicating that the generation of new fractures can greatly accelerate the imbibition rate. Research on the characteristics of water imbibition in hydrate sediments is important for optimizing hydrate production regime and increasing natural gas production.

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Investigation on the Application of NMR to Spontaneous Imbibition Recovery of Tight Sandstones: An Experimental Study

Energies ◽

10.3390/en11092359 ◽

2018 ◽

Vol 11 (9) ◽

pp. 2359 ◽

Cited By ~ 6

Author(s):

Chaohui Lyu ◽

Qing Wang ◽

Zhengfu Ning ◽

Mingqiang Chen ◽

Mingqi Li ◽

...

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Pore Size ◽

Early Stage ◽

Spontaneous Imbibition ◽

Size Distributions ◽

Pore Size Distributions ◽

Two Samples ◽

Tight Formations ◽

Nuclear Magnetic

In this paper, the nuclear magnetic resonance (NMR) technique is applied to exploring the spontaneous imbibition mechanism in tight sandstones under all face open (AFO) boundary conditions, which will benefit a better understanding of spontaneous imbibition during the development of oil & gas in tight formations. The advantages of nuclear magnetic resonance imaging (NMRI) and NMR T2 are used to define the distribution of remaining oil, evaluate the effect of micro structures on imbibition and predict imbibition recovery. NMR T2 results show that pore size distributions around two peaks are not only the main oil distributions under saturated condition but also fall within the main imbibition distributions range. Spontaneous imbibition mainly occurs in the first 6 h and then slows down and even ceases. The oil signals in tiny pores stabilize during the early stage of imbibition while the oil signal in large pores keeps fluctuating during the late stage of imbibition. NMRI results demonstrate that spontaneous imbibition is a replacement process starting slowly from the boundaries to the center under AFO and ending with oil-water mixing. Furthermore, the wetting phase can invade the whole core in the first 6 h, which is identical with the main period of imbibition occurring according to NMR T2 results. Factors influencing the history of oil distribution and saturation differ at different periods, while it is dominated by capillary imbibition at the early stage and allocated by diffusion at later time. Two imbibition recovery curves calculated by NMRI and NMR T2 are basically consistent, while there still exists some deviations between them as a result of the resolutions of NMRI and NMR T2. In addition, the heterogeneity of pore size distributions in the two samples aggravates this discrepancy. The work in this paper should prove of great help to better understand the process of the spontaneous imbibition, not only at the macroscopic level but also at the microscopic level, which is significant for oil/gas recovery in tight formations.

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Monitor the process of shale spontaneous imbibition in co-current and counter-current displacing gas by using low field nuclear magnetic resonance method

Journal of Natural Gas Science and Engineering ◽

10.1016/j.jngse.2015.08.069 ◽

2015 ◽

Vol 27 ◽

pp. 336-345 ◽

Cited By ~ 50

Author(s):

Mianmo Meng ◽

Hongkui Ge ◽

Wenming Ji ◽

Yinghao Shen ◽

Shuai Su

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Resonance Method ◽

Spontaneous Imbibition ◽

Nuclear Magnetic Resonance Method ◽

Low Field ◽

Magnetic Resonance Method ◽

Counter Current ◽

Nuclear Magnetic

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Experimental investigation of spontaneous imbibition process of nanofluid in ultralow permeable reservoir with nuclear magnetic resonance

Chemical Engineering Science ◽

10.1016/j.ces.2019.02.036 ◽

2019 ◽

Vol 201 ◽

pp. 212-221 ◽

Cited By ~ 7

Author(s):

Hongda Zhou ◽

Qingsheng Zhang ◽

Caili Dai ◽

Yuyang Li ◽

Wenjiao Lv ◽

...

Keyword(s):

Nuclear Magnetic Resonance ◽

Experimental Investigation ◽

Magnetic Resonance ◽

Spontaneous Imbibition ◽

Nuclear Magnetic

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Nuclear Magnetic Resonance Measurement of Oil and Water Distributions in Spontaneous Imbibition Process in Tight Oil Reservoirs

Energies ◽

10.3390/en11113114 ◽

2018 ◽

Vol 11 (11) ◽

pp. 3114 ◽

Cited By ~ 2

Author(s):

Xiangrong Nie ◽

Junbin Chen

Keyword(s):

Magnetic Resonance Imaging ◽

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Spontaneous Imbibition ◽

Oil Reservoirs ◽

Tight Oil ◽

Resonance Imaging ◽

The Core ◽

Tight Oil Reservoirs ◽

Nuclear Magnetic

Spontaneous imbibition of water into tight oil reservoirs is considered an effective way to improve tight oil recovery. We have combined testing techniques such as nuclear magnetic resonance, mercury injection capillary pressure, and magnetic resonance imaging to reveal the distribution characteristics of oil and water during the spontaneous imbibition process of tight sandstone reservoir. The experimental results were used to describe the dynamic process of oil–water distribution at the microscopic scale. The water phase is absorbed into the core sample by micropores and mesopores under capillary forces that dry away the original oil phase into the hydraulically connected macropores. The oil phase entering the macropores will drive away the oil in place and expel the original oil from the macropores. The results of magnetic resonance imaging clearly show that the remaining oil accumulates in the central region of the core because a large amount of water is absorbed in the late stage of spontaneous imbibition, and the water in the pores gradually connects to form a “water shield” that blocks the flow of the oil phase. We propose the spontaneous imbibition pathway, which can effectively explain the internal mechanisms controlling the spontaneous imbibition rate. The surface of the core tends to form many spontaneous imbibition pathways, so the rate of spontaneous imbibition is fast. The deep core does not easily form many spontaneous imbibition pathways, so the rate of spontaneous imbibition is slow. This paper reveals the pore characteristics and distribution of oil and water during the spontaneous imbibition process, which is of significance for the efficient development of tight oil.

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