Reservoir Commentary: Potential Implications of Long-Term Shut-Ins on Reservoir
Authors: SPE Reservoir Advisory Committee _ 
Published: August 2020

This commentary has been prepared by the SPE Reservoir Advisory Committee (RAC) to provide high-level insights for the discussion on the potential consequences of long-term shut-ins on conventional and unconventional reservoirs. The RAC comprises 61 subject matter experts (SMEs) covering the domain of reservoir technical discipline. The views presented in the commentary are the opinions of the SMEs and do not constitute an official position of the SPE on the subject matter. Find the full and unabridged version, including all references, at http://go.spe.org/RAC_Commentary.

Orientation

From a completions, production, and facilities perspective, there are significant, and potentially devastating, effects for the long-term shut-ins of wells.

Everything we leave in the well and the surface facilities will be subject to corrosion, deterioration, and other chemical/mechanical effects. Perforations and the well itself may become plugged and deformed and the pumps and bottomhole assemblies may be rendered dysfunctional due to the settlement of sand and other debris/contaminants. Moreover, scale buildup and wax and asphaltene precipitation in and around the wellbore are well-known potential problems during shut-ins.

The oil and gas industry has a very long history of well surveillance, well maintenance, and well remediation - but as an induction, we have not had any circumstances on the scale of the current situation. Simply put, we may not be able to bring these wells back on line without workovers and, in some cases, restimulation. Furthermore, recompletions, restimulations, chemical treatments, workovers, etc. may not be viable solutions in many cases, particularly for poorly performing wells, of which there will be many.

The impact on supply chains may/will be challenging in regards to the material, expertise, and timing to complete efforts for restimulation. These facts are indisputable, and have been recently documented in a JPT article by King and Garduno (2020) and in an SPE Live interview of George King by David Gibson (2020).

Experience With Shut-Ins in Conventional Reservoirs

Long-term shut-ins of conventional reservoirs for years and even decades have occurred under extraordinary circumstances - such as war or civil unrest (e.g., Iraq’s invasion of Kuwait in 1990, Arab Spring uprisings in early 2010s, and unrest in Nigeria from 2003 to 2007). In these cases, damages to the production facilities were catastrophic as the facilities had not been properly maintained, or as in the case of wars, the facilities and wells were destroyed. However, from a reservoir standpoint, there were also benefits of long-term shut-ins, in particular, due to repressurization of the field and stabilization of the fluid contacts (Dujardin et al. 2011).

Wells in conventional offshore reservoirs are routinely shut in for moderate periods (&lt;1 month) due to maintenance, seasonal demand, and weather-related issues - and, in many/most cases, there seems to be no significant nor permanent reservoir damage. In cases of severe water or gas coning due to aggressive production rates, stopping or reducing production may help stabilize fluid contacts. Rate reduction is also often correlated with higher recovery but the net-present value usually suffers.