Local drags of the completion string with packers in horizontal wells

Qimin Liang,Baokui Gao,Baolin Liu,Bairu Xia

doi:10.1177/0144598720964105

Abstract

The multistage stimulation technique and horizontal wells are increasingly being utilized to improve oil and gas recovery. However, the sticking that occurs due to large drag during the completion string with packers tripping into the horizontal section, resulting in an abandoned well and huge economic losses. Based on a classical drag model, this paper illustrates how local drags affect the overall stress of the completion string by a case study. Mechanical models are also presented for analyzing the local drag of packers in horizontal sections considering the effects of microsteps or slots, borehole curvatures, and caliper variation respectively. The results confirmed that the local contact force is affected by centralizers, and local drags can be magnified during their upward transmission process. It is revealed that the slopes of microsteps or slots affect more on local drag of packers than the effects of microsteps’s height and slots’ depth; Moreover, the local drag of the packer was found increases with the increase of the borehole curvature, but less affected by the caliper variation; As to the effect of cuttings on the local drag of packers, it is affected by cuttings size and cuttings amount and cannot be quantitatively analyzed. This research could be utilized as a theoretical reference for estimating the sticking risks of the completion string and conditioning the horizontal open hole.

Highlights

The horizontal well technology has been widely applied with the increase of development of oil and gas resources (Mason and Judzis, 1998; Viktorin et al, 2006), and the extension record of horizontal wells has been continuously updated with the advancement of horizontal well technology (Gao et al, 2009; Michael, 2012; Sonowal et al, 2009)
The above calculations indicate that the local drag variation of the completion string at the bottom of the horizontal well is not reflected in the total drag variation on the hook load, confirming that the local drag would be amplified during the upward transmission process
Under the same local drag condition, the local drag amplification effect is more obvious when picking up the completion string than when tripping in it

Summary

Introduction

The horizontal well technology has been widely applied with the increase of development of oil and gas resources (Mason and Judzis, 1998; Viktorin et al, 2006), and the extension record of horizontal wells has been continuously updated with the advancement of horizontal well technology (Gao et al, 2009; Michael, 2012; Sonowal et al, 2009). With the advancement of the completion technology, there are many completion types for horizontal wells, such as open hole, cased and cemented, screen pipe completion, and sliding sleeves with packers. A large number of production practices show that the fracturing technology is the most effective one to bring the best stimulation results and huge benefits to the development of oil and gas fields (McDaniel et al, 2002). This is mostly because hydraulic fracturing generally leads to highly complex hydraulic networks in reservoirs, which can enhance the well performance significantly (Yuan et al, 2018). When the completion string with packers trips into the long open hole section of a horizontal well, the drag of the completion string is changing constantly

Methods

Results

Conclusion