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.

The objective of this paper is to present the improvement in zonal isolation and cement sheath properties using foam cement in heavy oil Chichimene Field in Colombia. Achieving complete zonal isolation in the pay zone have become a major challenge in these fields, recently, given the complexity of the reservoirs: high permeability, low pressure, highly fractured, depleted, low fracture gradient, and cement column for well integrity. Despite advances in drilling technologies, such as MPD, massive losses still represent a major risk both drilling and cementing. Using commonly known cementing methods, like stage tool cementing and conventional slurries, have led to fair results. Foam cement technology emerged as an appropriate cementing method given its great properties both being pumped down, and once set Foam cement has several advantages over conventional methods: it prevents losses, enhances displacement efficiency in the annulus, provides a unique feature of density/strength ratio, and has improved resilience and elastic properties once set. Production liners in Chichimene and Castilla field have been cemented successfully with foam cement, even under severe well conditions as partial to severe losses. Full returns have been observed in all jobs while cementing, and cement has been seen at surface after circulating fluids out of top of liner. Good isolation has been obtained as per cement log evaluation. Foam cement has proved to be effective cement method to achieve proper isolation in difficult wellbores and has been of great benefit for cementing production zones in the mentioned fields. Novelty of the cementing process, described herein, delivers unique engineered features that have proven a major benefit to ensure well integrity in the fields. Cementing under critical wellbore conditions, still account for many costly remedial works, and this novel approach for cementing showed its benefits to achieve excellent results. Content of this paper could benefit many operators dealing with critical wellbores.

Sonic data are an important input to geomechanics models, and logging while drilling (LWD) sonic tools are an important source of these logs. A case study is presented from a field within the Llanos basin of Colombia where the field operator experienced wellbore stability problems in a 12 1/4‑in. hole section and needed to update the geomechanics model so the optimal mud-weight program and trajectories could be chosen. Collecting reliable LWD sonic logs, particularly formation shear-slowness logs, was challenging because both fast and slow formations were encountered within a single bit-run and, consequently, both high-frequency refracted shear and low-frequency quadrupole modes were required to obtain reliable formation shear-slowness values at all depths. This required the firing of multiple transmitter modes over a broad-range of frequencies and recording and storing the resulting large quantity of data for subsequent processing. How the required can be reliably recorded with the latest LWD sonic tools, and how the formation shear-slowness can be derived from the LWD quadrupole mode are described.

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The purpose of the study was to establish reference values for serum urea and creatinine, and for physical and chemical analysis in urine in Saimiri boliviensis. Fifteen females and 15 males raised in captivity at the Centro de Reproducción y Conservación de Primates No Humanos, !quitos, Peru were used. Mean values of urea and creatinine were 66.7 ± 25.2 and 2.0 ± 0.5 respectively, and without statistical differences between sexes. Mean values forpH was 6.9 ± 0.7 and for specific gravity was 1.021±0.004. Urea and creatinine values were higher to those reported for Aotus nancymae.