Issue 44

Q.-C. Li et alii, Frattura ed Integrità Strutturale, 44 (2018) 35-48; DOI: 10.3221/IGF-ESIS.44.04

Parameter

Value

Viscosity of fracturing fluid, u / mPa · s

1

Injection rate, Q / m 3 /min

6

Cluster spacing, H / m

30

Total fracturing time, T / min

10

Table 2 : Construction parameters of multi-cluster staged hydraulic fracturing.

The parameters in Tab. 1 and Tab. 2 are only for the standard model, whereas sensitivity studies can be performed by changing the corresponding parameters. On this basis, influences of the factors, such as cluster spacing and the injection rate of fracturing fluid, on the crack morphology are studied by using the FEA model.

S ENSITIVITY ANALYSIS

Effect of cluster spacing on fracture morphology roper cluster spacing is the key to the design of multi-cluster staged fracturing in horizontal wells. Therefore, in order to study the impact of cluster spacing on the fracture morphology (mainly the crack length and crack width), five different cluster spacings of 10m, 20m, 30m, 40m and 50m are examined. The width of all fractures studied in this paper is based on the value of the injection point. Fig.3 shows the contour of fracture morphology after fracturing for 10 minutes when the cluster spacing is different. P

Figure 3 : Contour of fracture morphology after fracturing for 10 minutes when the cluster spacing is different. (Deformation scale factor = 500).

In order to study the mutual interference of fractures during fracturing, an interference coefficient ( In ) is defined to characterize this response, which can be expressed by the following equation.

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