College of Geosciences, China University of Petroleum (Beijing), Beijing, 102249, China.
PetroChina Changqing Oilfield Company, Xi'an, 710018, People's Republic of China.
Sci Rep. 2023 Apr 21;13(1):6515. doi: 10.1038/s41598-023-33080-8.
In this paper, production system (PS) of shale oil is optimized according to production data and indoor experiments, including core and fluid tests. Results showed that: ① Pressure drop rate at wellhead is a reasonable reference for the determination of post-fracture shut-in duration (PFSID). When pressure at a wellhead of horizontal well is relatively stable and the pressure drop less than 0.1 MPa per day for three consecutive days, PFSID ends; ② Flowback intensity of fracturing fluid affects the effectiveness of proppant underground, thus flowback intensity can be determined by the critical flow rate and safety factor of each proppant; ③ Flowback intensity should be varied during different development stages, which could be divided into four according to production gas and oil ratio(GOR) of a shale oil horizontal well: low, medium-high, high and high-low production GOR. During the stage of low production GOR, ratio of flow pressure and saturation pressure should be maintained greater than 1.0, and the initial daily liquid productivity for a hundred-meter oil-bearing lateral length in a horizontal well is 2.4 ~ 2.9 m/d; and during the medium-high production GOR, high production GOR and high-low production GOR stages, the responding initial daily liquid productivity should be maintained between 0.8 ~ 1.0 or less than 0.8 respectively.
本文根据生产数据和室内实验，包括岩心和流体测试，对页岩油生产系统（PS）进行了优化。结果表明：① 井口压降率是确定压后停井时间（PFSID）的合理参考。当水平井井口压力相对稳定，且连续三天每天压降小于 0.1 MPa 时，PFSID 结束；② 压裂液的返排强度影响支撑剂在地下的有效性，因此可以通过每个支撑剂的临界流量和安全系数来确定返排强度；③ 在不同的开发阶段，返排强度应有所不同，可以根据页岩油水平井的产气量油比（GOR）将其分为四个阶段：低、中高、高和高低产 GOR。在低产气 GOR 阶段，流压和饱和压力比应保持大于 1.0，水平井每百米含油侧初始日产液量为 2.42.9 m/d；在中高产 GOR、高产 GOR 和高低产 GOR 阶段，应分别保持相应的初始日产液量在 0.81.0 或小于 0.8 之间。
