Innovation of Annular Sealants During the Past Decades and Their Direct Relationship with On/Offshore Wellbore Economics

Abstract

Annular sealants are used as static barriers to avoid fluid communication in-between zones and provide proper isolation of the different formations as well as support and protection to the casing. Therefore, the sealant can have a direct relationship to wellbore integrity. Data suggest more than 4 million hydrocarbon wells have been drilled globally; interestingly, some datasets indicate well integrity failure is highly variable (1.9 to 75%).Historically, sealants have been characterized for short-term placement properties up to the point at which the sealant is pressure tested and a log is performed to establish if the annulus is properly sealed. However, as hydrocarbon resources are becoming gradually depleted in easy-to-recover environments, harsher conditions are more common. Additionally, stimulation and enhanced oil recovery (EOR) techniques involving high-pressure and high-temperature (HP/HT) cycles during the entire well life pose significant challenges to the sealant's integrity.Sealant integrity issues can result in very high remediation costs, reduction of hydrocarbon production, and in some cases, loss of the well. All of these can lead to an increased cost per barrel of oil equivalent (BOE). During the last few decades, in view of the drastic changes in drilling conditions toward more challenging environments, the industry has opted for a sealant design approach, which considers all of the events that occur throughout the entire life of the well and their effects on integrity of the sealant and wellbore. This approach can be successful by employing analytical tools, which allow for synchronizing all of the different events and/or operations occurring during wellbore construction (from drilling to abandonment) with the different elements that encompass the wellbore architecture (geometry, formations, casing, and sealant). The use of these tools' forecasting capabilities can result in data-led decisions that allow operators to construct wellbores more efficiently and with more confidence, which should ultimately help reduce production costs.This study focuses on illustrating an analytical tool for predicting the sealant's performance in both onshore and offshore cases throughout the life of the well and determining how this affects wellbore economics in the long term. Moreover, this paper discusses how sealants have evolved from conventional Portland cements to elastic-, foamed-, glass-bead-extended cements, and epoxy-resins based on wellbore integrity predictions performed by analytical tools. The impact of nanomaterials in converting cement/ sealant systems into multifunctional and/or smart materials capable of self-sensing specific stimuli (i.e. stress, strain, etc.) is also shown.

Design and Evaluation of High-Temperature Well Cementing Slurry System Based on Fractal Theory

“…Wellbore conditions and casing program of deep wells and ultra-deep wells are complicated [6], which is why the operation in well-cementing operation is difficult. The influence of underground high temperature, high pressure, narrow clearance and other factors is usually considered in well-cementing operations [19,20].…”

“…At the same time, the permeability will increase, the sealing will lose efficacy, which will seriously affect the production safety of cementing well in a long life cycle. In the actual production process of oil and gas wells, the safety problem of wellbore sealing failure caused by high temperature is very common: in some countries, such as China, the United States and Norway, the proportion of wellbore isolation failure exceeds 20% [6]. It at least leads affect the production of oil and gas wells, and even more would lead to the abandonment of wellbore.…”

Coupled effects of hydrophilic nano silica oxide and anatase nano titanium oxide on strengths of oilwell cement

“…Excessive temperature induces distortion which leads to the failure of cement to provide long-lasting sealing (Won et al 2015). The poor performance in bottom wellbore conditions leads to costly repair operations, a reduction in production capacity, environmental disputes, and even loss of the well as the worst-case (Jimenez et al 2016). Portland cement also suffers degradation when exposed to varying conditions such as aggressive fluids; this makes it not suitable for well cementing for the CO 2 -rich environment (Xu et al 2019).…”

Cement sheath modification using nanomaterials for long-term zonal isolation of oil wells: Review

“…These features result in poor performance in bottomhole condition and finally, costly repair operations, reduction in production capacity, environmental issues, and in worst case loss of the well (Jimenez et al, 2016). Application of nanotechnology in well cementing is a promising approach to convert conventional cement system into multifunctional, durable system to deal with imposed stressful conditions for entire life of the well.…”

“…Application of nanotechnology in well cementing is a promising approach to convert conventional cement system into multifunctional, durable system to deal with imposed stressful conditions for entire life of the well. From cement sheath perspective, as hydrocarbon resources are becoming gradually depleted in easy-to-recover environments, hostile downhole conditions are more common (Jimenez et al, 2016). Additionally, thermal and stress cycles created by well events such as hydraulic fracturing, production, completion, steam injection, or remedial treatments during the well's life, poses significant challenges to the cement sheath integrity (Shadravan et al, 2014).…”