Staged Fracturing of Horizontal Wells in Continental Tight Sandstone Oil Reservoirs: A Case Study of Yanchang Formation in Western Ordos Basin, China

Shixue Cao,Yunfei Liu,Dingxue Zhang,Hui Luo,Xiao Li,Jingxin Cao

doi:10.3389/feart.2021.760976

Shixue Cao, Yunfei Liu + Show 4 more

Open Access

https://doi.org/10.3389/feart.2021.760976

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Abstract

Continental tight sandstone oil reservoirs have strong heterogeneity, and staged fracturing technology of horizontal well is a crucial measure for successful development of oil and gas. In this study, the fracturing effect of horizontal wells in tight oil reservoirs of Yanchang Formation in the western Ordos Basin was systematically studied using the rock mechanics, array acoustic and microseismic testing data and the staged fracturing technology. The hydraulic fracturing method was used to calculate the horizontal principal stress difference (σH-σh). It showed that as the buried depth increases, σH-σh tends to decrease first and then increase. Small-scale fracturing should be used for areas with smaller σH-σh values. Fracturing construction parameters have an impact on oil production capacity, which is mainly manifested in that the usage of prepad fluid, sand-carrying fluid and proppant is proportional to productivity. Excessive displacement and construction scale should not be used in the fracturing process, and the fracture height of the target layer should be strictly controlled within the range of 26 m. The analysis of the “rupture points” in the fracturing curves shows that wells with relatively obvious rupture points usually have a higher oil production capacity. These wells have a good fracturing effect and an effective fracture network was formed in the tight oil reservoir. The optimization simulation results of the horizontal well pattern form show that the seven-point combined well pattern is the best well pattern, which is suitable for the development of tight oil sandstone in the Yanchang Formation.

Highlights

Continental tight sandstone reservoir is a “hot spot” field for increasing oil and gas reserves and production capacity in the future (Chitrala et al, 2013; Bhatti et al, 2020; Hong et al, 2020; Abouzar and Ghanbarian., 2021)
Compared with vertical wells, horizontal wells can expose the reservoir to a greater extent and can increase the oil recovery rate of the entire reservoir significantly (Jaeger and Cook., 1976; Kang et al, 2010; Huang et al, 2019; Jiang et al, 2019; He et al, 2020)
Fractured horizontal wells will produce a series of fracture networks including transverse fractures, axial fractures and horizontal fractures

Summary

Introduction

Continental tight sandstone reservoir is a “hot spot” field for increasing oil and gas reserves and production capacity in the future (Chitrala et al, 2013; Bhatti et al, 2020; Hong et al, 2020; Abouzar and Ghanbarian., 2021). The change of stress during fracturing and Horizontal Well Fracturing the evolution of fracturing fractures are the most important research content for the staged fracturing of horizontal wells in tight sandstone oil reservoirs (Du and Aydin., 1993; Gurocak et al, 2012; Dong et al, 2020). The effect of hydraulic fracturing of horizontal wells is controlled by the geostress state in the tight oil reservoir and the fracturing construction measures (Li and Zhang, 1997; Liu et al, 2015; Lommatzsch et al, 2015; Li et al, 2018; Luo et al, 2018)

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