Zero Crude Oil Discharge for Non-Connected Wells During Temporary Flowback Applications: Another Milestone Achieved
Authors: Mashabi Loay , Al-Khadrawi Nader , Comin Otto , Alzarhani Abdulrahman 
Published: November 2015

Several milestones have been achieved towards preserving ambient air quality and eliminating source emissions in oil and gas operations. However, compromises were also made along that journey. One of the major compromise is the lack of flowback of non-connected wells for clean-up after rig operations. Delaying flowback of non connected wells had sometimes resulted in formation damage or absence of critical flow data. This paper explores solutions to flow back non-connected wells in a safe, timely and economical manner utilizing a spoolabe Reinforced Thermoplastic Pipe (RTP), eliminating the need to wait for permanent flowline/facilities hookup.

The main challenge to temporary flowback of non-connected wells are to provide a strong value proposition to clients and to design packages/procedures to conduct the operation safely and successfully. To tackle this issue, a multidisciplinary team involving client representatives, well testing companies and spoolable RTP manufacturers was established. Initially, a group of candidate wells was selected based on a range of GORs, flow rates, shut-in wellhead pressures and H2S content. This group was then filtered down to suitable candidates after a site visit to study terrain conditions and tie-in points’ proximity. The site setup included phase separators, surge tanks, sand management systems, scrapper launchers and receivers, RTP pipes and a contingency discharge system.

The selected pipes were 1500 psi MAOP 4″ ID RTP pipes with high temperature tolerance (up to 200 Deg. F). In addition, fiberglass reinforced pipes were preferred over galvanized steel reinforced ones due to their high H2S tolerance. A total of 1,750 meters of pipe were installed and spooled back in a matter of hours with an innovative deployment design. As a result, both selected wells were flowed-back successfully throughout the project. The trial test included a range of rates of up to 11 MBD, with up to 4% H2S content and up to 750 scf/stb GOR. In total, the cost of the operaion was only a fraction of the sale value of the crude oil recovered by the client. One of the wells was flowed back for logging purposes while the other for clean-up post workover operations.

The only hydrocarbon discharge was from the separated gas in one of the wells (observation well) as it had a low wellhead pressure and could not sustain flow against line back pressure. The gas was flared through a smokeless flarestack. The project was a great success with many operational lessons learned and a clear vision for the future that the paper discusses.

In order to eliminate the above situation of hydrocarbon flaring, the next step for the team is to include a mobile compressor that can boost the pressure of the gas separated in the phase separator and pump it into the line thus achieving 100% zero Hydrocarbon discharge to the atmosphere. A wide operating- range unit has been designed and is being built. The target trial test for the compression unit is in Q4 2015.