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.

Understanding the heat transfer phenomena encountered in extreme oil and gas reservoir environments [i.e., thermal recovery, high-pressure/high-temperature (HP/HT), deepwater, etc.] and geothermal wells is important to enhance the exploration and production of subterranean energy resources. However, there can be a lack of information about thermal properties of current oilwell cement systems, which are key inputs for any cement sheath stress simulator that accounts for the thermal cycling effect on the integrity of the annular sealant. Having thermal data for multiple sealant systems is important to allow for risk reduction and production maximization by reducing wellbore construction uncertainty during the planning stage, therefore allowing operators to make well-informed decisions. This paper discusses the thermal conductivity and thermal expansion of neat, foamed, and elastic oilwell cements. These properties were measured in hydrated and dehydrated states at ambient pressure and at temperatures ranging from 25 to 100°C (77 to 212°F). Both thermal conductivity and thermal expansion measured on dehydrated cement samples were less than hydrated samples, which is most likely attributed to the effect of evaporable water within the cement specimens. Mathematical relationships were derived for thermal and physical (i.e., density) properties of cement, thus allowing for approximate characterization of the thermal behavior of oilwell cements. The effect of the thermal properties of different cement systems on the integrity of a typical thermal recovery well was evaluated as a case study. Elastic properties of the aforementioned cement systems were also studied, yielding characteristic curves for each system. Moreover, the impact of cyclic loads on determining acceptable stress levels of annular sealants is also presented, along with its economic benefits. This allows for the optimal design of dependable sealants for long-term integrity during the planning stage.

Loss of circulation during the drilling stage in wellbore construction is a common issue, especially in a wildcat well. However, exploration is required to increase the reserves, and it frequently has to be performed in areas of difficult access and in deeper-water wells.Loss of circulation can significantly increase the operation cost, delay the drilling program, and can involve risks for the stages or even the well. It usually consumes more resources, such as mud, rig time, logistics, and modifications in the survey, etc. The outcome can be an ineffective use of time during well construction.A version of this paper was presented at PECOM 2009 in Mexico during the transformation through innovation providing an in-depth view of the current Mexican critical-technology issues. This manuscript focuses on how a severe loss of circulation was treated using a heat-activated, rigid rapid-fluid treatment, restoring full circulation and successfully increasing the window gradient in the first attempt in a deepwater wildcat well in the northern Gulf of Mexico. An engineered solution was proposed for the placement and calculations. It was verified through laboratory tests and in the field. In addition, this paper discusses the results of the application and how it was applied in the next drill stage based on a drill, tack-and-squeeze methodology. This method has become an alternative solution for the operator in this kind of well.

Recent studies have shown an increase in the percent of wells affected by sustained casing pressure over time. Both the oil and gas industry and governments are studying the causes of sustained casing pressure and methods to help prevent undesired flow that can potentially result in the loss of wellbore integrity and environmental problems.In the Caribbean region in northern Colombia, various natural gas production fields have been developed for decades. Because of mechanical problems or low economic return rates, some producing gas wells have been abandoned. Some wells in this area have been abandoned using conventional cement techniques without success, sometimes resulting in gas communication through the annulus to the surface. This has even been observed in some cases where the primary top of cement (TOC) was planned to surface. Potential gas communication through the wellbore annulus has been an issue in the industry for a long time. There are several factors influencing gas communication, such as flow through mud channels, micro-annuli, and flow through unset cement, among others. This paper presents the successful application of a new resin with superior mechanical properties and solids content designed according to the needs of the well, which allow it to penetrate areas previously inaccessible to conventional cement slurry, such as small fractures, channels, or micro-annuli. The case study presented shows how a sustained casing pressure problem was caused by a channel in the primary cement job. The novel resin system was pumped successfully as a squeeze job ahead of neat cement slurry to isolate the gas-producing formation, and no further gas production was observed at surface, bringing the well back into compliance with government regulations for proper well abandonment.

An increasing energy demand combined with the natural decline of old field discoveries has forced oil producers to develop and improve returns from existing assets. In Latin America, many major oil companies have been interested in heavy oils. Higher oil prices and improvements to technology allowing recovery factors up to 30% have made these reservoirs more attractive to operators. In Colombia, heavy oil fields are being developed in the Magdalena Medio area using steam injection as a thermal recovery method. Cyclic steam stimulation (CSS) is used and consists of three stages: injection, soaking, and production. Steam is first injected into a well for a certain amount of time to heat the oil within the surrounding reservoir to a temperature at which it flows. After sufficient steam has been injected, the steam is usually left to "soak" for a predetermined time period. Finally, oil is produced out of the same well. This process can cause high stress in the wellbore because of the high temperatures used and the cyclical nature of dramatic temperature changes. The elevated temperatures can reach up to 350°C (650°F) during thermal cycling, which, in turn, can potentially cause radial fractures or debonding of the cement, thus potentially compromising the zonal isolation. Achieving zonal isolation within these shallow vertical and horizontal wells (90° and 2, 200 ft measured depth [MD]/1, 396 ft true vertical depth [TVD]) and avoiding water communication between zones are the primary challenges encountered during these projects. This paper presents a successful methodology, lessons learned, and engineering design changes applied during the past three years to more than 200 wells in the Magdalena Medio area.