Abstract
Friction factor is an important parameter in the downhole drag & torque calculations and usually determined by inversion method. In traditional inversion calculation of friction factors, wellbore is divided into two sections, including cased hole and open hole, so that only two friction factors are introduced to characterize the drags in cased hole and open hole respectively. However, this traditional method is often not applicable for extended-reach well (ERW) in which the drag is usually too complicated to be characterized by only two friction factors. Therefore, more friction factors are needed to characterize drag in ERW more accurately.In this paper, the method of multi-segment friction factors inversion is proposed, that is, the wellbore of ERW is divided into several well sections and the same number of friction factors are introduced to characterize the drag in each of those well sections respectively. Meanwhile, to calculate these multi-segment friction factors, an inversion model, which is mainly based on Particle Swarm Optimization (PSO) and also integrates both Orthogonal Array Test Strategy (OATS) and Tabu Search (TS) method, is built.Then, the inversion model was applied to a case study to calculate multi-segment friction factors in casing running operation in a shale gas ERW. The result shows that the model is of high efficiency and accuracy, and moreover, multi-segment friction factors can provide more detailed drag information that is valuable for engineering decision-making.
Published Version
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