DeepLift - The Innovative Gaslift Bypass Packer Technique
Authors: Kongdachudomkul Chatchai , Kreethapon Thanawee , Pittrapan Pattana , Sompopsart Suwin , Toempromraj Wararit , Prayadsup Amnuay , Phloi-montri Pramote 
Published: March 2015

Producing more oil, but with less input power consumption challenges all E&P companies as they pursue sustainable energy resources. The innovative gaslift technique makes surmounting this challenge possible. The conventional gaslift well system has long been in use worldwide, but the design itself results in depth limiting of the lifting capability. Locating the side pocket mandrel just above the packer, where the gaslift valve is installed, as deep as possible is a well-known design. This might not be significant for short pay zone intervals with higher reservoir pressures, but, clearly, constraints arise in long true vertical perforation intervals with lower reservoir pressures. A new gaslift well design has been developed and studied by the PTTEP Well Engineering Team under the Company's "DeepLift" Project. This design has proven to be suitable for use in many types of wells, particularly those containing long true vertical perforation intervals. This new design was granted, by the U.S. Patent and Trademark Office, Patent No. 7,770,637 B2, on August 10th, 2010. The design comprises a single completion using the same tubing for producing hydrocarbons and delivering gaslift. The top section of the tubing targets producing hydrocarbons while the bottom section aims at delivering gaslift down to the wellbore. Gaslift flows through the perforated tube above the secondary port of the dual-packer, and then through bypass packer downward via a modified bypass string connected to the lower tubing section. Gaslift is injected out of the bottom side pocket mandrel via reverse gaslift valve to the wellbore, approximately at the bottommost perforation intervals, to improve outflow by decreasing the hydrostatic column or increasing the drawdown pressure. Wells that contained 500 - 600 mTVD, which is a significant long distance between the top and the bottom perforation depth, were selected for a field trial. An enormous percentage of production gain is due to genuine higher drawdown pressure improvement from 150 psi to 300 psi. This results in a significant production improvement, which is the primary discussion of this paper.

Introduction

The gaslift technique is one of the most common artificial lift methods currently used for oil producing wells. Conventional gaslift well systems have been used worldwide for decades. However, a bottleneck for the conventional gaslift well is depth-limit of which the deepest gaslift injection point is above the packer, whereas normally it is set just above the top perforation for gaslift well design and its integrity reason. The new gaslift well design, "DeepLift" proved suitable for use in many types of wells, particularly those containing long true vertical perforation intervals. This well design was inspired by a paper from the 11th PTTEP Technical Forum (2007), "Maximize Profit on Water Injector and Deepening Gaslift Injection Point - LKU-K16". The completion design was de-bottlenecked by deepening the gaslift injection point, which resulted in well deliverability improvement and reserve recovery by gaining a few more hundred barrels of oil per day.