玛北地区作为中国页岩油开发的新区块,其开发潜力巨大。然而,压裂产生的缝网结构对油井排采效率的影响尚未得到充分研究。因此,精确表征压裂缝网的特征是提升油井产量的关键。本研究通过对玛北地区7口页岩油井焖井后压力数据的监测,应用Bourdet（布德）方法绘制压降特征曲线,以评估缝网形态。进一步结合压裂参数和试产数据,对压裂缝网特征进行了综合评价。研究聚焦于缝网的主裂缝长度、次裂缝宽度、密度和渗透率等关键参数,旨在系统揭示缝网的发育特征。研究表明,玛北地区页岩油的压裂缝网可划分为3类：Ⅰ类缝网,主裂缝长度短、次裂缝宽度中等、缝网密度和渗透率高,压降导数曲线呈现偏左下的 “深V型”特征,表明该类缝网以导流能力为主导,能够有效提高油井排采效率;Ⅱ类缝网,主裂缝长度中等、次裂缝宽度宽、缝网密度中等和渗透率小,压降导数曲线呈现偏右上的“浅V型”特征,表明该类缝网以储集能力为主,尽管导流能力相对较弱,但仍具有一定的开发潜力;Ⅲ类缝网,主裂缝长度长、次裂缝宽度窄、缝网密度小和渗透率中等,整体缝网欠发育。其焖井压降导数曲线形态特征不明显,表明该类缝网在生产过程中见油晚,不利于油井高效开发。研究还揭示了一个重要规律：在破裂压力低的井中,若其他压裂条件相同,过高的每米加砂量易导致Ⅲ类缝网的形成。因此,为提高玛北地区页岩油开发效率,后续压裂设计中应着力避免形成Ⅲ类缝网。具体措施包括优化压裂参数（如合理控制每米加砂量）,以提升缝网的导流与储集能力,最终实现页岩油的高效开发。
As a new block for shale oil development in China, Mabei area has huge development potential. However, the impact of fracture network structures generated by hydraulic fracturing on oil well drainage efficiency has not been fully studied. Therefore, accurately characterizing fracture networks is crucial for improving oil well production. This study monitored the pressure data after shut-in of 7 shale oil wells in Mabei area and used the Bourdet method to plot pressure drop characteristic curves to evaluate the fracture network morphology. By integrating fracturing parameters and production test data, this study aims to provide a scientific basis for the efficient development of shale oil in this area. The study selected seven wells of shale oil in the Mabei area as research subjects. Initially, detailed monitoring of shut-in pressure data from these wells was conducted. Subsequently, pressure drop characteristic curves were plotted using the Bourdet method, which effectively reflects the morphology and characteristics of fracture networks. By analyzing the morphology and characteristics of the pressure drop derivative curves, combined with fracturing parameters (such as breakdown pressure and sand volume per meter) and production test data (such as oil breakthrough time and production rates), a comprehensive evaluation of fracture network characteristics was performed. The study focused on key parameters such as main fracture length, secondary fracture width, density, and permeability, aiming to systematically reveal the development characteristics of fracture networks. The results showed that fracture networks of shale oil in Mabei area could be classified into three types. Type I fracture networks had short main fracture lengths, medium secondary fracture widths, high density, and high permeability. The pressure drop derivative curves showed deep V-shaped characteristics leaning to lower left, indicating that this type of fractured network was dominated by conductivity and could effectively improve oil well drainage efficiency. Type II fracture networks had medium main fracture lengths, wide secondary fracture widths, medium density, and low permeability. The pressure drop derivative curves showed shallow V-shaped characteristics leaning to upper right, indicating that this type of fractured network was mainly storage-oriented. Although their conductivity was relatively weak, they still held certain development potential. Type III fracture networks, characterized by long main fracture lengths, narrow secondary fracture widths, low density, and medium permeability, were overall underdeveloped. Their shut-in pressure drop derivative curves lacked distinct morphological characteristics, indicating that this type of fractured network had late oil breakthrough during the production process and was unfavorable for efficient oil well development. The study also revealed an important pattern. In wells with low breakdown pressure, under the same fracturing conditions, excessively high sand volume per meter tended to lead to the formation of Type III fracture networks. Therefore, to improve shale oil development efficiency in Mabei area, subsequent fracturing designs should focus on avoiding the formation of Type III fracture networks. Specific measures include optimizing fracturing parameters, such as reasonably controlling sand volume per meter, to enhance the conductivity and storage capacity of fracture networks, thereby achieving efficient shale oil development. In conclusion, this study provides valuable insights into the characteristics of fracture networks in the Mabei shale oil area and offers practical recommendations for optimizing hydraulic fracturing operations to maximize well productivity. Future research can expand the sample size and incorporate numerical simulations and field experiments to further validate these findings and refine the strategies for efficient shale oil development.
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