致密砂砾岩储层纳米吸附气实验分析技术及其应用

Experiment analyzing technique of the nano-pore absorbed gas in the tight conglomerate reservoir and its application

松辽盆地徐家围子断陷沙河子组致密砂砾岩气勘探在Xt1井等取得重大突破,拓展了深层天然气勘探的新领域,但致密气储层含气性实验分析技术及评价相对薄弱。利用岩石纳米级样品制备装置和纳米吸附气提取装置,开展致密砂砾岩储层纳米吸附气提取、色谱检测条件及优化实验,确定了岩石纳米级样品最佳制样时间为20 min,纳米吸附气提取的最佳质量为20 g、时间为20 min、温度为80℃;气相色谱检测的最佳分析柱为OV-1填充柱,载气流速为40 mL/min,柱温50℃恒温0.5 min、以10℃/min升温到100℃恒温5 min,实验分析技术具有精确度高、快速等特点。徐家围子断陷沙河子组致密砂砾岩纳米吸附气实验分析结果表明,总烃质量体积为233.21～10 487.38μL/kg,不同井纳米吸附气烃组分特征差别明显,致密气具有近源成藏特征,源岩发育区为致密气有利探区,与致密砂砾岩储层压裂试气结果一致性好,为致密气储层含气性评价及勘探提供了实验依据。

Great breakthrough has been achieved in Well Xt1 and the other wells for the tight conglomerate gas exploration in Shahezi Formation of Xujiaweizi in Songliao Basin, thus the new field of the deep gas exploration has been expanded, however the analyzing technique and evaluation of the gas-bearing experiment for the tight gas reservoir are rather weak and limited. With the help of the preparing equipment of the nano-size rock sample and the desorbing instrument of the nano-size absorbed gas, the experiments of the desorption, chromatographic testing conditions and their optimizations were conducted for the tight conglomerate reservoir, the optimal prepared time ( 20 min) of the nano-size sample, the best desorbed mass (20 g) and time (20 min) and furthermore the temperature (80 ℃) of the nano-size absorbed gas were determined;the best analytical column of the gas-phase chromatographic test is OV-1 filling column, the flow rate of the carried gas is 40 mL/min, the column temperature is 50 ℃, the constant temperature lasts 0.5 min, the temperature rises to 100 ℃ and lasts for 5 min by 10 ℃/ min, the experimental analyzing technique is characterized by high precision, rapid speed and so forth. The results of the experimental analysis of the nano-size absorbed gas for Shahezi-Formation tight conglomerate in Xujiaweizi show that the total hydrocarbon content is 233.21-10 487.38 μL/kg, the differences are rather obvious for the component characteisitics of the different-well nano-size absorbed gas, the tight gas possesses the feature of near-source reservoir accumulation, the well-developed source area is the favorable block of the tight gas, the achievements are well accordant with the results of the tested gas for the fractured tight conglomerate reserovir, so the experimental evidences are provided for the gas-bearing evaluation and exploration of the tight gas reservoir.