Retarders are one of the most important additives in oilwell cementing for achieving the desired pumping time of cementitious slurry. Retarders are mainly extracted from natural sources, or they are chemically synthesized. However, synthesized retarders can have significant environmental effects. This paper proposes using coffee powder as a biocompatible retarder in oilwell cementing. This paper discusses a study wherein coffee powder was used as a cement retarder and its effect on other cement slurry properties was evaluated. Cement slurry was prepared and tested as per API RP 10B2 (2005) procedures for thickening time, compressive strength, fluid loss, and rheology. The performance of coffee powder was tested at various concentrations and temperatures up to 350°F. Its retardation activity was compared to a commonly used lignosulfonate-based retarder as well as a synthetic retarder. Coffee powder exhibited a predictable and linear thickening time behavior with respect to concentration and temperature variation. Testing at different temperatures revealed that coffee powder alone can be used at temperatures up to 350°F without need for a retarder intensifier. A concentration sensitivity study was performed at 125°F, and the coffee powder displayed expected results. To achieve similar performance, lower amounts of coffee powder are necessary compared to the lignosulfonate-based retarder. The performance of coffee powder was similar to the synthetic retarder. Furthermore, coffee powder does not cause adverse effects on other cement slurry properties, such as compressive strength development, fluid loss, and rheology. This work presents coffee powder performance as a cement retarder. Coffee is readily available, and it demonstrates a high performance and linear concentration response without hampering other cement properties.

Lost circulation is a recurring and costly challenge for the oil and gas industry. Losses range from seepage to total and financial effects, including nonproductive time and remedial operational expenses, which can increase potential risks to the operator. To address this issue, a tunable cement-based lost circulation treatment solution has been developed that is most suitable for partial to total losses, particularly when particulate-based solutions are not effective; the solution is primarily intended to cure losses while drilling. Unlike conventional lost circulation materials (LCMs) that cure losses by mechanical bridging of particles, the thixotropic cement solution's effectiveness arises from its unique chemical composition, which is ideal when flow paths are too large to be plugged by particles. The new lost circulation treatment solution is thixotropic with a density range of 10 to 15 lbm/gal working in temperatures up to 250°F. The formulation can be mixed with fresh water, seawater, or seawater with up to 14% NaCl. It is designed and tested in accordance with API RP 10B2 (2013) procedures for thickening time (TT), compressive strength, static gel strength, fluid loss, and rheology. During the TT on-off-on test, the formulation builds gel strength when shear is reduced and regains fluidity when shear is reapplied. The formulation developed rapid static gel strength and an early compressive strength up to 500 psi. The reversible gelation behavior is demonstrated through multiple shear on-off cycles. This solution is operationally convenient to apply because it can be pumped through the bottomhole assembly (BHA), thus reducing trip times. Because of its acid solubility, it can be used across production zones. The unique properties of gaining rapid gel strength reversibly and a good compressive strength render this solution effective for treating a wide range of lost circulation events during drilling. A wider density window might minimize the potential risk of inflow when treating losses.

Cementing a casing string across weak formations or depleted reservoirs has the added challenge of tailoring the cement slurry to meet delivery criteria (i.e., density and rheology) while maintaining the mechanical properties of the set cement necessary to provide a dependable barrier. To help prevent fracturing the formation and inducing losses, cement density is often reduced, which strongly influences the mechanical properties of set cement. Common strategies for reducing cement density consist of adding water in the cement slurry; using additives such as hollow glass microspheres (HGS), synthetic latex, and elastomers; using foam cement; or adding resin. This paper discusses how cement slurries with reduced densities are designed using both traditional and alternative methods of making cement/resin composites and provides insight into the advantages and drawbacks of each. Stable cement slurries with a density of 13 lbm/gal were designed, and placement characteristics of thickening time and rheology were evaluated for the liquid cement slurry. Unconfined compressive strength (CS), Young's modulus (YM), tensile strength, permeability, and shear bond were investigated on the cured samples. Before taking mechanical and permeability measurements, slurry stability was verified using sedimentation testing. Any slurry that did not exhibit the necessary stability was redesigned and tested again. Only the final slurry designs exhibiting stability are discussed in this paper. Cement-resin composite cements exhibited similar performance to those containing HGS in terms of CS, YM, tensile strength, and shear bond but exhibited greater than two times the CS when compared to the synthetic latex modified, water-extended, and elastomeric slurry designs. The cement-resin composite provided almost twice the shear bond strength and increased tensile strength by 50% compared to other slurry compositions. In the current work, cement-resin composite, synthetic latex modified, microbead-based, water-extended, and elastomer-modified slurries are compared at 13 lbm/gal. Various parameters, such as mixability, ease of placement in the annulus, strength development, and long-term cement integrity, are evaluated. Traditional and newly introduced techniques for reducing cement slurry density and the resultant mechanical properties of the set solids are investigated. This information provides an alternate method of using cement-resin composites for designing and delivering dependable barriers tailored for low density applications.

A well-executed cement operation is fundamental for successful zonal isolation. One method used to confirm the success of a cementing operation is cement bond-log (CBL) analysis. Various factors contribute to good bond strength at the casing-cement interface; a better shear bond helpsminimize the risk of communication between different zones and also maximize production by avoiding undesirable fluid diversion during well intervention. To enhance shear-bond strength, a thin layer of coating material can be applied on the external surface of casing before running itin the well. Variouscoating techniquesare available, such as spraying, dipping, or simply brushing. Polymer emulsions, thermosetting polymers, and inorganic-based coatings can be applied. This paper studies the effect of various coating materials on shear-bond strength. A coated casing sample was concentrically placed inside another largercylinder and cured after filling the annular space with cement slurry. Once cured, the shear-bond strength was experimentally measured using a hydraulic press. The results obtained with various coating materials are compared to those from an uncoated control sample. The shear-bond setup was prepared with neat standard cement slurry and cured for 3and 7days for testing. Three different types of casing coating wereevaluated for enhancing shear-bond strength—inorganic-based, aqueous polymer emulsion, and thermosetting resin. All three coatings providedenhanced shear-bond strength compared to the control sample. The inorganic-based coating almost doubled the shear-bond strength. The aqueous polymer emulsion coating increased shear bonding by approximately 30%. Finally, the thermosetting resin coating resulted in a much smaller increase in shear bonding compared to the other treatments; however, it was observed to provide better resiliency while applying loads during testing. A thin layer of coating onthe entire length of a casing column does not significantly increase costs. On the contrary, significant value is providedthrough better shear-bond strength and potential corrosion resistance. Therefore, this practice can eliminate the necessity of remedial treatments later. Additionally, applying the inorganic-based coating on the outer surface of casing pipe provides additional bond-strength between the cement and casing, minimizing the risk of inner debonding. The coating application process is operationally simple and can be readily implemented, and it provides a low-cost, dependable barrier. In addition to providing better bonding, coating can also inhibit corrosion and increase the life of the tubular.

Nowadays good quality natural river sand is not readily available; it is to be transported from a long distance. These resources are also exhausting very rapidly. So there is an urge to find some alternative to natural river sand. Natural river sand takes millions of years for its formation and is not renewable. As a substitute to natural sand, Artificial (Manufactured) sand is used as a complete replacement. Considering the gap in research, this paper presents the effect of the use of Foundry sand as fine aggregate in concrete as a substitute to Artificial Sand. The experimental work is mainly concerned with the study of mechanical properties like compressive strength, split tensile strength as well as flexural strength of concrete by partial replacement of artificial sand by foundry sand as fine aggregate. Tests were carried out on cubes, cylinders and unreinforced beams to study the mechanical properties of concrete using foundry sand and compared with concrete with artificial sand as fine aggregate. Artificial sand was replaced with five percentage (0%, 5%, 10%, 15%, and 20%) of WFS by weight. A total of five concrete mix proportions (CM, F-1, F-2, F-3 and F-4) with and without WFS were made. Compression test, splitting tensile strength test and flexural strength tests were carried out to evaluate the strength properties of concrete at the age of 7 and 28 days. Test result showed a nominal increase in strength and durability properties of concrete by addition of WFS as a partial replacement of fine aggregate.