In the Khurmala field, Kurdistan, a challenging water injection well required the cementing of a 7" liner while managing pre-existing formation losses. The primary objectives were to prevent further losses during cementing and ensure long-term zonal isolation, given the cement’s continuous exposure to bottom-hole pressures of 3000 psi during water injectivity post-completion. A novel ultra-lightweight (ULW) flexible cement slurry with a density of 9.5 ppg was developed to maintain equivalent circulating density (ECD) below the fracture point. The slurry was designed to provide improved mechanical properties for sustained zonal isolation under high-pressure conditions. To meet the challenges of cementing a 7" liner in the Khurmala field’s loss-prone formation, a 9.5 ppg ULW flexible cement slurry was developed. The slurry was designed to maintain the ECD below the formation’s fracture gradient, preventing losses. Mechanical properties, including Young's modulus and Poisson’s ratio, were optimized using Cement Stress Analysis software and extensive lab working to ensure flexibility, minimize micro-annuli, and withstand high injection pressures. The slurry blend was engineered for homogenous particle distribution to achieve a compressive strength of 2000 psi, ensuring consistent mechanical performance. A spacer with bridging LCM was also designed to mitigate losses. Extensive laboratory testing was performed under simulated downhole conditions, confirming its ability to maintain zonal isolation and structural integrity under continuous high-pressure exposure. The cement mixing and pumping operations were carried out as planned, with no losses encountered during the job. Post-job cement bond log (CBL) results demonstrated exceptional zonal isolation and bond quality. The cement successfully maintained its integrity under continuous exposure of 3000 psi, confirming the effectiveness of the design and the field application of the ULW flexible cement slurry. The Ultra-light weight slurry and improved mechanical properties ensured safe cement placement without inducing losses and ultimately provided long-term well integrity. The key novelty of this work is the development and field application of a 9.5 ppg ultra-lightweight flexible cement slurry designed for long-term zonal isolation in water injection wells. The slurry’s mechanical properties were tailored to withstand high-pressure conditions while ensuring long-term durability over extended time, even when exposed to compression, traction, and potential creation of micro-annuli. The approach provided an innovative solution to the challenges of cementing in weak formation, delivering both immediate operational success and sustained well integrity.
This paper addresses the challenge of placing a cement plug to isolate an open hole section in a workover well in northern Iraq's Khurmala formation, which was experiencing total losses and increased water production. The plug needed to be accurately placed to avoid cementing the lower perforation zone. A cement slurry design was formulated to efficiently isolate the water zone under total loss conditions, making it particularly effective for squeezing applications. This paper addresses the challenge of placing a cement plug to isolate an open hole section in a workover well in northern Iraq's Khurmala formation, which was experiencing total losses and increased water production. The plug needed to be accurately placed to avoid cementing the lower perforation zone. A cement slurry design was formulated to efficiently isolate the water zone under total loss conditions, making it particularly effective for squeezing applications. Several fluid design approaches have been taken to design a successful slurry. First, to address the total losses condition of the open hole, the decision to use an 11 ppg slurry was mainly to reduce the hydrostatic pressure exerted by the cement column while introducing fluid loss control properties as well as optimizing the rheology. Furthermore, a specialized gelling agent was introduced to the design that enables the slurry develop a self-supporting characteristic as soon it is left in a static condition. As these were the key aspects of the design, more parameters and constraints that were identified and addressed will be discussed further in this paper. As the job was executed, the success of the design was assessed according to industry standards. Initially contaminated cement was observed at surface while circulating out at the TOC indicating the presence of cement fluid at the intended interval. Subsequently, post the wait on cement period, the plug was tagged at the desired depth indicating that the squeezing operation has been successfully performed in a single attempt, eliminating the need for excessive resources, solutions, time and cost that would otherwise be required for this kind of challenge and eventually the hydrocarbon production is increase significantly. The novelty of this approach lies in designing a lightweight cement slurry with the key self-supporting characteristic while maintaining API fluid loss value, static gel strength, compressive strength development, and rheology. Remarkably, this dual-function solution has never been designed/utilized before, setting a new standard in cement slurry design.
In the Khurmala field, Kurdistan, a challenging water injection well required the cementing of a 7″ liner while managing pre-existing formation losses. The primary objectives were to prevent further losses during cementing and ensure long-term zonal isolation, given the cement's continuous exposure to bottom-hole pressures of 3000 psi during water injectivity post-completion. A novel ultra-lightweight (ULW) flexible cement slurry with a density of 9.5 ppg was developed to maintain equivalent circulating density (ECD) below the fracture point. The slurry was designed to provide improved mechanical properties for sustained zonal isolation under high-pressure conditions. To meet the challenges of cementing a 7″ liner in the Khurmala field's loss-prone formation, a 9.5 ppg ULW flexible cement slurry was developed. The slurry was designed to maintain the ECD below the formation's fracture gradient, preventing losses. Mechanical properties, including Young's modulus and Poisson's ratio, were optimized using Cement Stress Analysis software and extensive lab working to ensure flexibility, minimize micro-annuli, and withstand high injection pressures. The slurry blend was engineered for homogenous particle distribution to achieve a compressive strength of 2000 psi, ensuring consistent mechanical performance. A spacer with bridging LCM was also designed to mitigate losses. Extensive laboratory testing was performed under simulated downhole conditions, confirming its ability to maintain zonal isolation and structural integrity under continuous high-pressure exposure. The cement mixing and pumping operations were carried out as planned, with no losses encountered during the job. Post-job cement bond log (CBL) results demonstrated exceptional zonal isolation and bond quality. The cement successfully maintained its integrity under continuous exposure of 3000 psi, confirming the effectiveness of the design and the field application of the ULW flexible cement slurry. The Ultra-light weight slurry and improved mechanical properties ensured safe cement placement without inducing losses and ultimately provided long-term well integrity. The key novelty of this work is the development and field application of a 9.5 ppg ultra-lightweight flexible cement slurry designed for long-term zonal isolation in water injection wells. The slurry's mechanical properties were tailored to withstand high-pressure conditions while ensuring long-term durability over extended time, even when exposed to compression, traction, and potential creation of micro-annuli. The approach provided an innovative solution to the challenges of cementing in weak formation, delivering both immediate operational success and sustained well integrity.
We have studied a series of Pd/Au alloys as Pt-catchment materials, both in lab-scale experiments and in an industrial ammonia oxidation plant. Our focus has been on how bulk Pt diffusion affects grain reconstruction in Pd/Au alloys (91/9 and 50/50 at. %) during Pt-catchment, performed by studying both polycrystalline (as produced) and quasi-monocrystalline (preannealed in vacuum) wires. The grain reconstruction is reduced when alloying Pd with Au, and it is almost absent for Pd/Au (50/50 at. %). For all Pd-containing samples with a quasi-monocrystalline grain structure, the restructuring is limited in short (<20 days) laboratory experiments but present in the 5 month industrial experiment. Notably, the Pd/Au (50/50 at. %) alloy shows a low degree of restructuring in all experiments but a reduced Pt-catchment in the industrial experiment. The mechanism for grain reconstruction of Pd/Au alloys is discussed, along with the role of the Kirkendall effect and the internal porosity on wire restructuring.
A structured reactor with annular configuration was applied for studying methanol oxidation to formaldehyde over silver. By eliminating gas phase reactions, high formaldehyde selectivity (93-97%) was obtained at low methanol and oxygen conversion under practically isothermal reaction conditions. CH2O and CO2 were the only carbon containing products, and both may be claimed as primary products along with H-2. It also proves that CO is formed by homogenous decomposition of CH2O and should not be considered a main precursor to CO2, as assumed in several reaction mechanisms. The analysis of H-2/CO2 ratio as a function of temperature provides an estimate of contributions from dehydrogenation and partial oxidation of methanol, and clearly suggests presence of a dehydrogenation pathway to CH2O. Extracting kinetic parameters is challenging due to a correlation between activity, oxygen dissolution, and silver restructuring and morphology and its dependence on temperature. Nevertheless, the data indicate 1st order with respect to oxygen. Conditioning by reaction at high temperature followed by a temperature ramp was performed to minimize the impact of a gradually changing Ag catalyst. The resulting Arrhenius analysis implies two distinct regions of activity. The apparent activation energy was estimated to 41 kJ/mol for the high temperature region, a value close to the activation energy for oxygen diffusion in silver at high temperature. The investigation demonstrates benefits of using an annular reactor configuration in bridging lab scale investigations with industrial conditions. Collecting reaction data at low oxygen conversion is enabled, which has not been achievable in conventional lab scale reactors this far.
