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Abstract Wellbore cementing is critical for zonal isolation, bonding and supporting the casing downhole. In this paper, a novel high-performance micromaterial is presented for significantly improving the quality of the cement slurry and set cement tested in different API cements for horizontal wells. Its performance is compared to conventional Pozzolanic materials currently used in increasing cement properties. Strongly attractive for cementing horizonal wells, the innovative micromaterial provides excellent slurry stability, free water control, particulate suspension, and additional fluid loss control to superior set cement properties including high early compressive and tensile strengths, extremely low permeability, and zero shrinkage. This material offers consistently high performance and no variability of product quality as compared to Pozzolan materials that are derived as a by-product of coal burning. The key novelty and invaluable contribution of this research to the field is the application of a unique high-performance micromaterial that can deliver multiple desirable properties in both slurry and hardened cement. With the illustration of the material giving many good surprising properties, the cement design can be optimized by reducing the dosage of several cement additives in the admixture, giving potential cost savings to service companies or operators. During our investigation, the new material does not require an additional chemical to activate its unique functionality.
Pernites, Roderick (BJ Services) | Brady, Jason (BJ Services) | Padilla, Felipe (BJ Services) | Clark, Jordan (BJ Services) | Ramos, Gladyss (BJ Services) | Callahan, Jaron (BJ Services) | Garzon, Ricardo (BJ Services) | Sama, Raymond (BJ Services) | Embrey, Mark (BJ Services) | Fu, Diankui (BJ Services) | Johnson, David (Independent Resources Management) | Richey, Nicolas (Independent Resources Management)
Abstract Increasing horizontals, narrowing annular gaps, more stringent cement regulations, fracturing with more stages and high pumping rates on top of more cost-efficient well completion are raising demand for lightweight cements, which are designed to prevent damage and lost circulation problems in weaker formations. However, many alternative lightweight materials that are more cost effective than glass beads, which are known to provide superior strength, are increasing waiting-on-cement time, thus delaying further drilling. They also struggle to deliver the required compressive strengths. This paper presents (1) recent case histories of successful field applications of new stronger non-beaded lightweight cement, (2) extensive laboratory data of various field designs with new lightweight cement versus premium commercial lightweight cements, and (3) detailed scientific study explaining how the innovative lightweight cement has provided superior fluid stability and set cement mechanical properties. The successful field trials occurred in the Permian basin for all four wells on the same pad. About 400 bbl of the new lightweight cement at 10.5 lbm/gal density was delivered to complete each cementing job with 134°F BHST and 6,000-ft measured depth. The four wells were completed with the new lightweight cement, remarkably having no glass beads despite the extremely low density. Unlike the previous job designed with commercial lightweight cement, the new cement has provided far greater compressive strength and has shown faster (18 to 24 hr) strength development. During placement, the new lightweight cement slurry has demonstrated exceptional stability with fewer additives than the previous design, thus simplifying field operations. Multiple laboratory test data at different cement densities (10.5 to 14.5 lbm/gal) for other regions confirmed the enhanced performance of the new lightweight cement in both slurry form and set cement over conventional lightweight technologies. Detailed scientific study via X- ray Diffraction (XRD) explained how the new lightweight cement provided superior set cement performance. The novelty of this work and invaluable contribution to the industry is the first successful field application of a newly developed micromaterial that provided a lighter, stronger, low-permeability, non-beaded cement that enhances wellbore integrity and provides better zonal isolation. New findings from XRD and Scanning Electron Microscopy (SEM) imaging techniques about the new micromaterial lightweight additive may provide insights for improving the performance of traditional materials.
Rollins, Brandon (Whiting Petroleum Corporation) | Lauer, Travis (Whiting Petroleum Corporation) | Jordan, Andrew (BJ Services) | Albrighton, Lucas (BJ Services) | Spirek, Matthew (BJ Services) | Pernites, Roderick (BJ Services)
Abstract Frequently exposed weak formations require the use of lighter slurries, and with increased wellbore pressures encountered during fracture stimulations, stronger cements are essential. Lighter, stronger cementing technologies are the key to ensuring well integrity and enabling simple, cost-effective well construction designs. This paper describes the benefits and features of newly developed, lightweight cementing materials available for operations in the Williston Basin. Applications of these materials are supported by case histories and extensive laboratory test data. Regionally, materials have been identified that can be used to produce innovative, bulk lightweight cementing systems. These materials can be inter-ground with the cement during manufacturing or blended with bulk cement. Both methods create cost-effective, high-strength cement systems that can easily be formulated into slurries with densities as low as 10.5 ppg. Comprehensive laboratory test data was generated to support well simulations and field trials of the new materials. Field trial data is then analyzed to illustrate the benefits of cement systems. Economical lightweight cements are commonly produced with fly ash extended systems, however, these systems have low strength at low densities. Lightweight, high-strength, fit-for-purpose cement materials are common in southern oil and gas basins, but transporting these materials to northern states is cost prohibitive. Exotic solutions to create lightweight cements (nitrogen foams or hollow glass micro-beads) are available but expensive, adding considerable operational complexity. Laboratory data demonstrates mechanical properties of the cement systems, slurry properties and set characteristics. The new, low-density cement systems show far greater compressive strengths than conventional blends. Conventional slurry provides a compressive strength of 500 psi, whereas the new low-density 12 ppg blends provide compressive strengths greater than 1,000 psi. Additional practical benefits of these systems are illustrated by varying water content to improve slurry density from 11 to 13.5 ppg without additional cementing additives. Multiple case histories illustrate the results of the applications of these materials at downhole temperatures ranging from 140°F to 220°F and well depths up to 11,000 ft TVD in the Dakota, Mowry and Charles Salt formations. The limitations associated with traditional cementing materials will no longer restrict the creation of efficient well designs in northern states with the implementation of new, low-density cement systems necessary to exploit these oil and gas basins. Using lighter, stronger cement technologies will provide simple, cost-effective designs that are needed to ensure wellbore integrity in the Williston Basin.
Today’s North American land drilling and cementing are facing new challenges due to increased hydrocarbon extraction, especially in the Permian basin. For instance, operators in the region frequently face severe losses during drilling or cementing, which are not prevalent in the other US basins. Lost circulation is a major problem that increases well construction costs and time as well as delays well completion and production in a market where efficiency and costs are the main drivers.
Solutions to this perennial problem include two-stage cementing, contingency liners, and use of lightweight cement systems. Lightweight cement reduces hydrostatic pressure to prevent losses particularly in weak formations. Typically, lightweight cements are designed by incorporating expensive micro spheres and/or foam. These designs are relatively costly compared to conventional technologies, and they involve operational complexity in the field. There are other cost-effective materials that allow for designing lower density cements, which have pozzolanic reactivity to increase strength of the set cement. But these traditional materials cannot provide enough compressive strength in the 10.3 ppg to 11.5 ppg density range.
In this paper, several case histories will be presented from more than 100 jobs pumped to date. The selected job(s) will be explained with real-time acquisition data, and these data will be compared to pre/post-job computer simulations to explain the dynamics of the placement. Numerous field applications of the novel and cost-effective non-beaded lightweight cementing technology will be described. The new lightweight has a lower hydrostatic pressure during pumping, hence preventing the occurrence of lost circulation. It also delivers superior strength after cement setting, thereby providing better zonal isolation and mechanical support to the casing. Because of its efficient delivery utilizing the same equipment, processes and personnel, this new cementing technology is easily integrated into the current field operations.
The novel contribution to the industry is the successful field application of a non-beaded lightweight low permeability cement to more than 100 jobs. This lightweight cement is uniquely formulated with a new unconventional micromaterial that provides superior strength performance, improved operational efficiency, and safety combined with better economics over beaded or foamed cement system. Based on multiple jobs that were completed, this innovative lightweight cement has successfully mitigated losses, thus maintaining lower equivalent circulating densities to achieve the required top of cement. It also eliminated the need for multiple cementing stages, thereby enabling faster well completion and dramatically reducing well construction costs.
Abstract The use of lightweight cement systems to plug loss zones, reinforce wells in weak formations, and enforce zonal isolation is well established. Performance failure is costly and undesirable. Remedial work could result in both high costs and nonproductive time. In extreme cases, an entire well could be lost. Performance of a lightweight cement system is limited by its design strength, which directly affects the maximum placement depth. Conventional water-extended cement slurries are not considered adequate for unconventional reservoirs such as shale and sandstone. Use of ceramic microsphere and glass beads in cement formulations with reduced slurry densities has steadily increased over time. However, in cases where formulation stability is compromised, field application of these slurries is challenging because of the limits in operational latitude. In fact, density segregation due the use of glass beads is one cause of formulation instability. Locally available raw materials have been found to combine with carefully selected glass microspheres in lightweight cement tested at nearly double the mechanical strength of a conventional control formulation. The resulting slurry showed improved rheology and fluid loss control for optimal performance in the well under bottomhole conditions. Because the combined material improves predictability of downhole density, complete circulation can be achieved when deploying this slurry. The new slurry design should enable placement of lightweight cement in deeper wells, with improved pumpability and on-location rheology and set time control. This paper describes the formulation, lab test results and postulates the mineralogy differentiation through use of XRD testing.