Unlocking Production Enhancement in Onshore Monobore Completion with Mechanical Artificial Lift

Abstract

Monobore was implemented in PHSS since 1996, replacing conventional completion to reduce drilling cost and simplified rigless well intervention. today, more than 500 monobore wells has been completed. This project is expected to give at least 80BOPD gain per well, increasing production reliability, and economically profitable for company.

During the lifecycle of the well, Natural Flow will be the first method to exploit hydrocarbon from a reservoir. Later on, in extended NF period, gaslift could be used to modify wellbore liquid in order to be lifted by its pressure. As reservoir getting depleted, and watercut started to increase, at some point, GL will not be effective to make the well flow at stable rate. This period, as experienced by PHSS for some years back, has raised the sense of urgency to implement mechanical pumps, especially on monobore wells.

The main challenge is that slim monobore completion was designed to accommodate NF and GL well, but will give some limitations for mechanical pumps. Small wellbore diameter, absence of annulus and tight wellhead footprint in dual monobore completion, with additional equipment required to insert downhole pumps and sucker rod has to be addressed to solve the issue instead of adding future complexions.

Due to the lack of monobore wells with mechanical pumps in Indonesia, references are limited and pumps will be fabricated and shipped from overseas. Thus, well data and forecast has to be taken into account, since the pumps will ready at least 6 months after finalized design.

At first, well with liquid gross increment opportunity was chosen, not included those with sand/solid problems, as it is the major threat for mechanical pumps. Then, similar candidate are organized to finally came up with candidate tiers ranking. Lab test was also conducted, in together with gathering updated data from well reactivation attempts.

Discussion with service companies was done simultaneously to grab knowledge and evaluate artificial lift limitation in fluid tolerances, downhole pump capacity, surface footprint, power requirement and simplicity to conduct rigless operation. Finally, economic analysis and procurement strategy was developed to ensure company satisfaction in trial period while stay fair to vendor Thru Tubing ESP and insert-PCP has been decided to be implemented to replace Permanent Coiled Tubing Gaslift (PCTGL) as current artificial lift. One major classification is TTESP will be use in dual monobore completion while iPCP is for single monobore due to surface footprint and economic consideration. 15 well is identified to be TTESP candidate in 3 Tiers, and <10 wells as iPCP candidates. This tier ranking system will provide candidate “backup” for every tier, that will simplify procurement and evaluation process.