Classification of tight sandstone reservoirs based on NMR logging

Classification of Tight Sandstone Reservoirs Based on the Nuclear Magnetic Resonance T2 Distribution: A Case Study on the Shaximiao Formation in Central Sichuan, China

“…The characteristic parameters (ω 1 , ω 2 , ω 3 , and μ 1 ) of the T 2 distribution extracted using the Gaussian distribution function can not only characterize the pore structure of reservoirs but also represent the seepage capacity of reservoirs. However, the direct use of these four parameters in reservoir classification may lead to deviations in the judgment of seepage capacity, and the data of different types of reservoirs will overlap, making it difficult to classify the reservoirs . When the four parameters are combined, the difference between data will be highlighted and better classification results will be achieved.…”

“…The Gaussian distribution function is used to fit the NMR T 2 distribution. The probability density function (PDF) of the Gaussian distribution is expressed as − where T 2 is the NMR transverse relaxation time expressed in ms, ∑ i = 1 n ω i = 1, 0 < ω i < 1 ( i = 1– n ), and ω i , μ i , and σ i are the i th weight coefficient, mean, and standard deviation, respectively.…”

“…However, the direct use of these four parameters in reservoir classification may lead to deviations in the judgment of seepage capacity, and the data of different types of reservoirs will overlap, making it difficult to classify the reservoirs. 28 When the four parameters are combined, the difference between data will be highlighted and better classification results will be achieved.…”

Development of High-Temperature and High-Mineralization-Resistant Adaptive Plugging Agent and Its Performance Evaluation

“…The NMR transverse relaxation time T 2 is proportional to the pore size, the signal amplitude is proportional to the amount of fluid within the corresponding pore size, and the area enclosed by the curve (peak area) is proportional to the total volume of pores in the core. Therefore, the volume change of pores after ADS sealing can be analyzed by the change of peak area . At the same time, the core can be imaged by NMR, and through pseudo-color processing, different colors can be used to indicate different water saturation in the core, with red indicating 100% saturation and blue indicating no water.…”

“…Therefore, the volume change of pores after ADS sealing can be analyzed by the change of peak area. 23 At the same time, the core can be imaged by NMR, and through pseudo-color processing, different colors can be used to indicate different water saturation in the core, with red indicating 100% saturation and blue indicating no water.…”