World's First Digital Gas Lift Application in Dual Completion Technical & Economic Consideration for Successful Implementation
Authors: Tiar Saloua , Rubio Erismar , Albelazi Abobaker , Ofodile Azubuike , Abdulsallam Fouad , Al Karra Mohamed , Al-Khatib Haitham , Al Attar Mohamed , BenAmara Abdel , Faux Stephen , Makin Graham 
Published: November 2019

The dual completion technique is considered very attractive by major oil companies as it offers significant CAPEX saving while maximizing oil recovery. Even though the first dual completion installation was in the 1960s, applications have been limited since it requires especial completion equipment, complicated run in/out hole procedures and challenging artificial lift implementation. Dual completions are also complicated by a lack of production control equipment. All these factors constrain the deployment of this potentially profitable completion technique worldwide.

API 19G9 advises that dual-string gas lift is problematic and often ineffective. It is difficult, or even impossible to effectively producing both completed zones in a dual-string gas-lifted well, due to the complexity of controlling gas injection using conventional pressure operated valves.

The string dedicated to the formation with the lowest productivity and reservoir pressure tends to divert the gas from the other string. Additionally, fluctuating casing pressure, unpredictable temperature gradients due to the proximity of the two strings, and inability to individually controlling the injection rates to each string makes simultaneous production optimization of these wells extremely complex.

The majority of ADNOC Onshore dual completion wells are equipped with gas lift mandrels in only one of the strings, limiting the production from the naturally flowing string when water breaks through. Few wells in ADNOC Onshore have both stings on Gas lift. For these that do, the optimization of the amount of gas required for each zone is difficult and requires multiple wireline operation to change orifice sizes, causing increased operational risks.

To overcome the production and operations constrains of existing gas lift practice in dual completion wells; the authors developed a dual string well design employing digitally controlled integrated gas lift valves. This design enables the adjustment of the gas lift injection rates for each of the strings without the need of rig-less intervention. Furthermore, the desing allows the simultaneous recording of downhole temperature and pressure at gas injection depth in each producing string.

This paper describes the technical and economic evaluation of the pilot implementation of DIAL technology in dual completions across ADNOC Onshore, covering the candidate selection criteria, integrated evaluation of the well performance & surface debottlenecking scenarios, completion design considerations, best practice Installation and data integration system that ensure achieving a set of success criteria and targeting additional 20% extra production per well.

This Worldwide first implementation of digital gas lift production optimization system in a dual string well, will be a game changer in the industry, enabling efficient production and enhanced recovery from both reservoirs within the same well. If successful, it is expected to achieve an additional production gain while reducing 30 % of the gas consumption.