A method and device for evaluating the dynamic water lock effect of coal by using low-field nuclear magnetic resonance
A low-field nuclear magnetic resonance and water lock effect technology, which is used in the analysis, measurement device, and material analysis through resonance by using nuclear magnetic resonance. It can solve problems such as interference, and achieve the effect of accurate results and simple operation.
Active Publication Date: 2020-06-30
CHINA UNIV OF GEOSCIENCES (BEIJING)
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Problems solved by technology
[0021] For coal and rock, due to its low porosity and low permeability, the calculation of water production using the traditional volume method will produce large errors, and at the same time, it will be interfered by the core end effect
Method used
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Experimental program
Comparison scheme
Effect test
Embodiment
[0110] Example—Evaluation of dynamic water lock effect of low-rank coal in Tarim Basin
[0111] Follow the steps below:
[0112] 1. Sample preparation and loading
[0113] (1) Drill the low-rank coal columnar coal core HvB-1 from the Tarim Basin, the core diameter is 25 mm, the length is 50 mm, the weight is 32.34 g, and dried in a drying oven to constant weight;
[0114] (2) After evacuating the core for 6 hours, pressurize saturated water at 10.0 MPa for 48 hours. Take out the saturated core and immerse it in distilled water. At the beginning of the experiment, dry the water on the surface with filter paper and put it into a non-magnetic core holder;
[0115] (3) Slowly put the core holder into the nuclear magnetic resonance measurement cavity, and prepare for the measurement of the nuclear magnetic relative permeability.
[0116] 2. Prepare for the experiment
[0117] (1) Apply a confining pressure of 3.0MPa to the core holder loaded into the core to simulate the format...
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Abstract
The invention discloses a method and device for evaluating dynamic water locking effect of coal by adopting low field nuclear magnetic resonance. The method comprises the following steps: starting a pressure gradient formula and a Darcy law to establish a dynamic water locking evaluation model through the simultaneous equation, and finally obtaining a series of water locking starting pressure gradient numerical values corresponding to different saturation degrees through experiment and computation. A device for evaluating the dynamic water locking effect of the coal by using the low field nuclear magnetic resonance is dedicatedly designed for the method; the device comprises a gas supply system, a gas-water displacement system, a nuclear magnetic measurement system and a data collection system; the nuclear magnetic displacement experiment is performed on a columnar coal sample of the saturation water by the device under the room temperature and the confining pressurizing state, the water yield is monitored in real time by utilizing the nuclear magnetic resonance T2 spectrum, and then the accurate gas-water relative permeability curve is acquired, and a dynamic water locking evaluation model is established; the intuition and the sensitivity of the low field nuclear magnetic technology is fused, the operation is simple and the result is accurate, and the method is a dynamic andreal-time new testing method.
Description
technical field [0001] The invention relates to the field of coalbed methane exploration and development, in particular to a method and device for evaluating the dynamic water locking effect of coal by using low-field nuclear magnetic resonance. The present invention is mainly used for quantitatively evaluating the dynamic water locking effect of coal, but it is also suitable for evaluating the water locking effect of other unconventional tight reservoirs, such as shale, tight sandstone and the like. Background technique [0002] The water locking effect is an important factor affecting the production and production of oil and gas wells. In unconventional reservoirs with low permeability and ultra-low permeability, the water locking effect is more significant due to the small pore throats. At present, the definition of water-locking effect at home and abroad refers to that in the process of oil and gas development, when drilling fluid, completion fluid and other foreign flui...
Claims
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IPC IPC(8): G01N24/08
CPCG01N24/081
Inventor 姚艳斌袁学浩刘大锰蔡益栋罗万静
Owner CHINA UNIV OF GEOSCIENCES (BEIJING)