Abstract
Hydraulic extended-reach limit (HERL) model of horizontal extended-reach well (ERW) can predict the maximum measured depth (MMD) of the horizontal ERW. The HERL refers to the well’s MMD when drilling fluid cannot be normally circulated by drilling pump. Previous model analyzed the following two constraint conditions, drilling pump rated pressure and rated power. However, effects of the allowable range of drilling fluid flow rate (Qmin ≤ Q ≤ Qmax) were not considered. In this study, three cases of HERL model are proposed according to the relationship between allowable range of drilling fluid flow rate and rated flow rate of drilling pump (Qr). A horizontal ERW is analyzed to predict its HERL, especially its horizontal-section limit (Lh). Results show that when Qmin ≤ Qr ≤ Qmax (Case I), Lh depends both on horizontal-section limit based on rated pump pressure (Lh1) and horizontal-section limit based on rated pump power (Lh2); when Qmin < Qmax < Qr (Case II), Lh is exclusively controlled by Lh1; while Lh is only determined by Lh2 when Qr < Qmin < Qmax (Case III). Furthermore, Lh1 first increases and then decreases with the increase in drilling fluid flow rate, while Lh2 keeps decreasing as the drilling fluid flow rate increases. The comprehensive model provides a more accurate prediction on HERL.
Highlights
Wang and Guo (2008) first proposed the concept and the computational model of Hydraulic extended-reach limit (HERL) theory[2]
The pump power is maintained at Pr when Q > Qr, the pump pressure keeps decreasing as drilling fluid flow rate Q increase
The rated pump pressure of drilling pump pr and the rated power of drilling pump Pr as two constraint conditions of HERL model for horizontal extended-reach well (ERW) are provided under the conditions of Q ≤ Qr and Q > Qr respectively
Summary
Wang and Guo (2008) first proposed the concept and the computational model of HERL theory[2]. Sun (2013) further developed the HERL model, he regarded the rated power of drilling pump as a new constraint condition[5]. The HERL model based on new constraint condition is introduced These studies only consider the effects of rated pressure of www.nature.com/scientificreports/. Drilling pump and rated power of drilling pump on the HERL model; the allowable range of drilling fluid flow rate, an important hydraulic parameter range, was not taken into consideration. The rated pump pressure of drilling pump pr and the rated power of drilling pump Pr as two constraint conditions of HERL model for horizontal ERW are provided under the conditions of Q ≤ Qr and Q > Qr respectively. The effects of allowable range of drilling fluid flow rate on the HERL model are not considered. The allowable range of drilling fluid flow rate is expressed in Eq (2)
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