Developing Oil In Monobore Well Completion Using Permanent Coil Tubing Gas Lift Application By Ari Taufiq Kramadibrata; Pahala Panjaitan; Sumaryanto, SPE, 1 Aug 2011

VICO Indonesia has operated the Sanga-Sanga PSC in East Kalimantan, Indonesia, since 1968. More than 750 development wells have been drilled to date in the complex Mahakam Delta in East Kalimantan. The mature reservoirs are predominantly gas, extremely depleted and have an average recovery factor of about 70%. To optimise the development cost, VICO changed the completion from multi-string and multipackers to monobore in 1997 and furthermore to dual monobore in 2005. VICO also has the focus to optimise oil production and recovery. The current oil recovery factor is relatively modest and needing further detail study and optimisation.

A multi-disciplinary team was developed to further evaluate oil potential in all VICO fields, including review of historical performance, geology and development opportunities. These reservoirs were also evaluated using material balance to understand the initial volumes in place, the drive mechanism and the opportunity to maximise production and oil recovery through the existing wells.

One of the challenges in maximising oil recovery is applying artificial lift in monobore completion. VICO has evaluated and selected gas lift as optimum artificial lift method. There are two possibilities to gas lift oil wells: (1) using conventional dual string completion and (2) gas lift in dual monobore completion.

The paper describes an innovative gas lift system in monobore completion where gas lift mandrels were not pre-installed. This technique has been implemented by running 1.5" coil tubing into a well through a special tubing hanger attached to the top of the Christmas tree. This technique allows gas lift to an oil reservoir in monobore well completion without requiring a rig for recompletion. This application is known as 'Permanent Coil Tubing Gas Lift' (PCTGL). This technique has been implemented in the 'MUT-X' well that wasn't capable of flowing naturally, and then PCTGL was installed to resume oil production. The well was flowing 600 bopd initially and now it continues flowing at 350 bopd. The wellbore schematic is shown in Figure 1, and the surface configurations are shown in Figure 2a and Figure 2b.

In summary, PCTGL is a proven favourable and simple method for artificial lift application in monobore completion to maximise oil production and recovery. Furthermore, this technique has helped VICO in synergising gas and oil development to maximise the value of the assets.