Abstract
The tight and thick sandstone reservoir, which is represented by Huaqing oilfield, was stimulated by the separated layer fracturing technology in the early period which produces discharge multi-channel between the pay formation and wellbore. For the conventional refracturing technology, the combination of tubing and packers is employed to treat the target layers in sequence. Nevertheless, this conventional technology is confined by the size of the tubing so that the maximum pumping rate can only reach to 3 to 4m3/min. It can’t meet the requirement of high pumping rate of hybrid fluid SRV fracturing that the treatment effort is not optimum and the stimulation efficiency is very low. In this article, in order to resolve the refracturing problems above for old wells, we introduced a state-of-art downhole releasing separated layer volume fracturing technology and support tools. By applying the releasing tool assembly and exclusive fishing tools, some goals can be easily achieved: to realize the efficient isolation between target layers, to protect the casing while fracturing, to meet the pump rate requirement of SRV fracturing of 11m3/min. We deployed the pilot field experiment of Huaqing oilfield and realized the “separated layer multistage SRV fracturing” of tight and thick reservoir. The result shows that the initial production rate of trial wells increases by 2.42t/d. The field test indicates that this technology presents some advantages such as high pump rate, simple tool assembly, easy operation and low operation risk.
Highlights
The technologies of unconventional oil and gas field development such as the Bakken high pressure and tight reservoir in North America have evolved rapidly
Taking the Chang 6 reservoir of Huaqing Oil Field for example, oil reservoir is thick for directional wells and the interlayer develops, which results that the vertical producing degree of hybrid fluid volume fracturing in single layer is not enough
The hybrid fluid SRV fracturing with high pump rate is the key technology to efficiently stimulate the tight sandstone reservoir
Summary
The technologies of unconventional oil and gas field development such as the Bakken high pressure and tight reservoir in North America have evolved rapidly. The combination of 3D seismic, detailed reservoir description, horizontal wells, volume fracturing and diagnosis, factory-like operations, leads to the rapid production increase [1,2,3,4,5]. Less domestic and foreign research on directional well volume fracturing of separate layer has been done. Taking the Chang 6 reservoir of Huaqing Oil Field for example, oil reservoir is thick for directional wells and the interlayer develops, which results that the vertical producing degree of hybrid fluid volume fracturing in single layer is not enough. In order to increase the stimulated volume and reservoir producing degree, the technique and tools of directional well volume fracturing in separate layer has been developed so that the downhole releasing volume fracturing technology of separate layer was eventually formed
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