Feasibility Evaluation of Using Downhole Gas-Water Separation Technology in Gas Reservoirs with Bottom Water

Abstract

Many gas reservoirs are water driven. Water supplies an extra mechanism to produce the gas reservoir, but it can create production problems in the wellbore. These water production problems are more critical in low productivity gas wells.Water loads up the gas well, when a lot of gas remains in the reservoir. Conventional technologies of gas well dewatering remove water from inside the wellbore without controlling water at its source. Downhole gas-water Separation (DGWS)technolgy was developed. It separates gas from produced water inside the wellbore and injects the produced water into the disposal zone. Two types of separators have been used hydrocyclone and gravity separators. The aim of this work is to evaluate the using of DGWS for gas wells comparing simulated performance of a conventional well. The simulation runs were made over a various range of the initial reservoir pressure and permeability values for a gas reservoir with bottom water drive. The results show considerable incremental recovery of a DGWS over conventional - a 3.3 - fold recovery increase for reservoir with 1500 psia pressure and permeability 1 md. The study also identified the challenges during DGWS applications. A good candidate well for DWGS installation must have a high-quality disposal zone with sustainable permeability with good vertical and mechanical isolation between the production and injection formations. Finally, downhole gas-water separation technology has a great potential in gas well dewatering and reservoir development especially in low pressure-low permeability gas reservoirs.

Water Production Problem in Gas Reservoirs: Concepts, Challenges, and Practical Solutions

“…Since the difference between densities of water and gas is high, separation naturally occurs in the borehole. e DGWS technology can be classified into two main categories: gravity separation and hydrocyclone separation [17].…”

“…e appropriate injectivity and disposal zone quality are key factors in choosing a well for the DGWS application, and the candidate reservoir should have sufficient remaining reserve. Furthermore, disposal formations must be isolated from the production zone [17]. e DGWS technology has great potential in gas well dewatering and reservoir development, especially in low-pressure/low-permeability gas reservoirs [17].…”

“…Furthermore, disposal formations must be isolated from the production zone [17]. e DGWS technology has great potential in gas well dewatering and reservoir development, especially in low-pressure/low-permeability gas reservoirs [17]. A Canadian company installed a special DGWS system that improved the production in comparison to other DGWS systems; moreover, some operating conditions were developed.…”

“…Water production decreases the recovery by reduction of the life of the reservoir [17][18][19], limits productivity and efficiency of wells, and elevates safety risks in gas production. Water production can cease the well from production by water loading or make the production economically deficient.…”

Downhole water drainage from a gas reservoir for water dumpflood in an underlying oil reservoir

“…Radwan [4] investigated the feasibility of the downhole gas-water separation (DGWS) technique in order to improve gas recovery in the bottom water drive gas reservoir. The concept of DGWS is the separation of gas and water inside the well and separated water is injected into the same aquifer.…”