| Controlling Effects of Tight Reservoir Micropore Structures on Seepage Ability: A Case Study of the Upper Paleozoic of the Eastern Ordos Basin,China |
| |
| 作者姓名： | YANG Bo QU Hongjun PU Renhai TIAN Xiahe YANG Huan DONG Wenwu CHEN Yahui |
| |
| 作者单位： | State Key Laboratory of Continental Dynamics; Dept. of Geology, Northwest University, Xi’an 710069, China |
| |
| 基金项目： | the National Natural Science Foundation of China(Grant No.41390451,41172101);the National Key Research Project of China(No.2016YFC0601003). |
| |
| 摘 要： | In this study, the types of micropores in a reservoir are analyzed using casting thin section(CTS) observation and scanning electron microscopy(SEM) experiments. The high-pressure mercury injection(HPMI) and constant-rate mercury injection(CRMI) experiments are performed to study the micropore structure of the reservoir. Nuclear magnetic resonance(NMR), gas-water relative seepage, and gas-water two-phase displacement studies are performed to examine the seepage ability and parameters of the reservoir, and further analyses are done to confirm the controlling effects of reservoir micropore structures on seepage ability. The experimental results show that Benxi, Taiyuan, Shanxi, and Shihezi formations in the study area are typical ultra-low porosity and ultra-low permeability reservoirs. Owing to compaction and later diagenetic transformation, they contain few primary pores. Secondary pores are the main pore types of reservoirs in the study area. Six main types of secondary pores are: intergranular dissolved pores, intragranular dissolved pores, lithic dissolved pores, intercrystalline dissolved pores, micropores, and microfracture. The results show that reservoirs with small pore-throat radius, medium displacement pressure, and large differences in pore-throat structures are present in the study area. The four types of micropore structures observed are: lower displacement pressure and fine pores with medium-fine throats, low displacement pressure and fine micropores with fine throats, medium displacement pressure and micropores with micro-fine throats, and high displacement pressure and micropores with micro throats. The micropore structure is complex, and the reservoir seepage ability is poor in the study areas. The movable fluid saturation, range of the gas-water two-phase seepage zone, and displacement types are the three parameters that well represent the reservoir seepage ability. According to the characteristic parameters of microscopic pore structure and seepage characteristics, the reservoirs in the study area are classified into four types(Ⅰ–Ⅳ), and types Ⅰ, Ⅱ, and Ⅲ are the main types observed. From type Ⅰ to type Ⅳ, the displacement pressure increases, and the movable fluid saturation and gas-water two-phase seepage zone decrease, and the displacement type changes from the reticulation-uniform displacement to dendritic and snake like.
|
| 关 键 词： | micro-pore structure SEEPAGE ability movable fluid SATURATION the range of GAS-WATER two phase SEEPAGE zone DISPLACEMENT types |
| 收稿时间： | 2018/10/17 0:00:00 |
| 修稿时间： | 2019/1/17 0:00:00 |
Controlling Effects of Tight Reservoir Micropore Structures on Seepage Ability: A Case Study of the Upper Paleozoic of the Eastern Ordos Basin,China |
| |
| Authors: | YANG Bo QU Hongjun PU Renhai TIAN Xiahe YANG Huan DONG Wenwu CHEN Yahui |
| |
| Abstract: | In this study, the types of micropores in a reservoir are analyzed using casting thin section (CTS) observation and scanning electron microscopy (SEM) experiments. The high‐pressure mercury injection (HPMI) and constant‐rate mercury injection (CRMI) experiments are performed to study the micropore structure of the reservoir. Nuclear magnetic resonance (NMR), gas‐water relative seepage, and gas‐water two‐phase displacement studies are performed to examine the seepage ability and parameters of the reservoir, and further analyses are done to confirm the controlling effects of reservoir micropore structures on seepage ability. The experimental results show that Benxi, Taiyuan, Shanxi, and Shihezi formations in the study area are typical ultra‐low porosity and ultra‐low permeability reservoirs. Owing to compaction and later diagenetic transformation, they contain few primary pores. Secondary pores are the main pore types of reservoirs in the study area. Six main types of secondary pores are: intergranular dissolved pores, intragranular dissolved pores, lithic dissolved pores, intercrystalline dissolved pores, micropores, and microfracture. The results show that reservoirs with small pore‐throat radius, medium displacement pressure, and large differences in pore‐throat structures are present in the study area. The four types of micropore structures observed are: lower displacement pressure and fine pores with medium‐fine throats, low displacement pressure and fine micropores with fine throats, medium displacement pressure and micropores with micro‐fine throats, and high displacement pressure and micropores with micro throats. The micropore structure is complex, and the reservoir seepage ability is poor in the study areas. The movable fluid saturation, range of the gas‐water two‐phase seepage zone, and displacement types are the three parameters that well represent the reservoir seepage ability. According to the characteristic parameters of microscopic pore structure and seepage characteristics, the reservoirs in the study area are classified into four types (I–IV), and types I, II, and III are the main types observed. From type I to type IV, the displacement pressure increases, and the movable fluid saturation and gas‐water two‐phase seepage zone decrease, and the displacement type changes from the reticulation‐uniform displacement to dendritic and snake like. |
| |
| Keywords: | micro-pore structure seepage ability movable fluid saturation the range of gas-water two phase seepage zone displacement types |
| 本文献已被 CNKI 维普 等数据库收录！ |
| 点击此处可从《Acta Geologica Sinica》浏览原始摘要信息 |
| 点击此处可从《Acta Geologica Sinica》下载免费的PDF全文 |
|
