High-efficiency casing perforation oil and gas wells

The energetic capabilities of a high-speed jet of an aqueous solution of polyethylene oxide (PEO) with varying concentration and different outflow pressures from a jetforming nozzle were investigated using the length of the forming channel in the model of the casing of an oil and gas well, cement sheath and rock layer, as well as impact of the jet force on a metal plate fixed on a physical pendulum. The experimental data made it possible to obtain a calculated dependence in a dimensionless form to determine the quality (initial sections) of jets of aqueous solutions with different concentrations and molecular weights of PEO, considering the real parameters of the jet-forming nozzles of the hydroperforator. A comprehensive study of the perforation process made it possible to substantiate the mechanism of the high destructive capacity of a high-speed jet of polymer solution. It has been established that the mechanism of the high destructive capacity of the polymer water jet is not due to the Toms effect, but caused by the destructive action of the dynamic pressure of the polymer water jet «reinforced» by strongly unfolded macromolecular chains under the action of a tensile flow in the inlet area of the jet forming nozzle of the hydroperforator. Keywords: perforator; jet nozzle; jet quality; casing; cement sheath; rock; Toms effect.

Application of Tire Waste Material to Enhance the Properties of Saudi Class G Oil Well Cement

Cementing is an important operation for the integrity of the wellbore due to its role in providing several functions. To perform these functions, a high performance cement is required. Different types of additives and materials have been added to the cement slurry to improve its performance. Tire waste material is considered one of the greatest wastes globally. It is a dangerous material to the environment and human. Subsequently, it has been included in many industrial processes to reduce its hazards. This work evaluated the application of tire waste material in oil and gas industry to improve the properties of Saudi class G oil well cement. Two cement slurries were formulated under high pressure and high temperature of 3000 psi and 292 °F, respectively. The first slurry was the base cement without tire waste and the second slurry contained the tire waste. The effect of using the two slurries on the cement properties such as density variation, compressive strength plastic viscosity, Poisson's ratio and porosity was evaluated. The results showed that, when tire waste material was used, lower density variation was accomplished. Using tire waste was efficient to decrease the density variation to an extremely low proportion of 0.5%. Adding tire waste to the cement composition decreased its plastic viscosity by 53.1%. The tire waste cement sample had a higher Poisson's ratio than the base cement sample by 14.3%. Utilizing the tire waste improved the cement's compressive strength by 48.3%. The cement porosity was declined by 23.1% after adding the tire waste. Beside the property's enhancement in the cement, the application of tire waste has also an economical advantage, since it is inexpensive material which is influential in our daily life.

Wellbore Integrity and CO2 Sequestration Using Polyaramide Vesicles

A new cementing additive is chemically engineered to react with formation fluids that act antagonistically towards cement. Engineered polymer capsules house encapsulants to react with antagonistic gases downhole like CO2 to form a more benign and beneficial material. Embedded in cement, the polymer capsules with semi-permeable shells allow fluids to permeate and react with encapsulants to produce beneficial byproducts, such as calcite and water from CO2. Reactivity between the encapsulant and antagonist gas CO2 is demonstrated using thermal gravimetric analysis (TGA) and other tests from oilfield equipment. When cement fails, casing-in-casing events, or CCA, causes antagonistic gases like CO2 to migrate to the surface. Embedded in the cement for such moments such as cement failure, additives housed within polyaramide vesicles chemically and physically intersect CO2 from gas migration events. The shape of the polyaramide additive is unique and versatile. Furthermore, because the material is polymeric, it imparts beneficial mechanical properties like elasticity to cement. A vesicle in form, this polymer allows the manufacturing of new cement additives for applications such as increasing the integrity and sustainability of oil well cement. Data also shows production of calcite by the bulk of the material. This technology applies to CO2 fixation and self-healing cement using reactive polymer vesicles.

Triazine Polymers for Improving Elastic Properties in Oil Well Cements

The oil well cement placed in the annulus between casings and the formations experience high stresses under downhole conditions. These frequent stresses deteriorate the mechanical properties of cement and lead to the formation of micro-cracks and fractures, which affect production and increases the cost of operation. Although several polymeric materials have been employed to improve tensile properties of the cement, these additives have also adversely affected the compressive strength of the cement. A highly stable polymeric additive, triazine-based polymers, is designed, synthesized, and compounded with the cement to improve the tensile properties of the well-cement. Triazine polymer was characterized by fourier transform infrared spectroscopy and thermogravimetric analysis. The triazine polymer was mixed with cement and the cement slurries were cured at 180 °F under 3000 psi for 3 days. The set-cement samples were subjected to mechanical testing under high temperature and high pressure to study the elastic properties of the cement. The introduction of this polymer into the cement has improved the elastic properties of the cement with minimum reduction in compressive strength. The thickening time, dynamic compressive strength development, rheology, fluid loss properties, and brazilian tensile strength of the control and cement with triazine polymers were studied to understand the effect of this newly developed polymeric additive. The molecular interaction of the triazine polymer with cement particles has shown formation of covalent linkage between the polymer and cement particle. We have observed a 15 % decrease in Young's modulus for cement compounded with 2%wt. of triazine polymer, indicating the introduction of elastic properties in wellbore cement.