Raising the Bar of Productivity Improvement in an Abnormal and Distinctive Pressure and Temperature Environment: Niger Delta.

Imbazi, Oyeintonbra (Shell Company in Nigeria) | Ugoh, Oluwatobi (Shell Company in Nigeria) | Okoloma, Emmanuel (Shell Company in Nigeria) | Osuagwu, Micheal (Shell Company in Nigeria) | Enyioko, Chigoziem (Halliburton) | Ighavini, Emmanuel (Halliburton) | Uzodinma, Chioma (Halliburton)

OnePetro 

Abstract

Well 01 and Well 02 are part of the phase 1-6 project that involved the development of six wells with the potential to deliver an additional 70% production increase to the LNG export market. The sand face for both wells was drilled with 0.72psi/ft pseudo oil-based mud (POBM). After the initial well clean-up, both wells produced sub-optimally (~20% of estimated potential) with relatively high drawdown (ranging from 500psi – 1000psi). This low production was suspected to be because of downhole (screen and formation) impairment or partial opening of the formation isolation valves (FIV).

A restoration team was set up with a responsibility to proffer a robust well intervention execution plan and select the most potent barite dissolver. Nine stimulation chemicals were tested and based on the team criteria, CHEM-001 and CHEM-002 were selected as main-treatment and pre-flush chemicals, respectively.

The downhole and surface conditions that exist in deep high-pressure wells pose many challenges to the coiled tubing industry as it strives to provide safe and reliable access to the wells. This paper highlights a case history of successfully snubbing coiled tubing (CT) into two deep (about 14,000ft+) live wells (Well 01 and Well 02) with a high surface pressure (7000psi+) and temperature (80 – 100°C) to stimulate both wells. The success criteria post stimulation was targeted at 75% of the potential production value. However, post treatment results show that cumulative gas production increased by 375% (with about 200psi) with a potential to increase up to 400%.

This paper details the entire operations during the CT well intervention, the planning, design, and technical analysis which led to the selection of a CT with 130,000psi yield strength on a 125K CT injector system, force simulations, and laboratory tests on CT with stimulation chemicals which led to a successful stimulation campaign. The paper also covers the initial planned versus actual operations and the lessons learned leading to on-the-spot optimization plans that resulted in a highly successful intervention operation.