Experimental Methods for the Evaluation of the Efficiency of an Innovative Sulfur-Dissolving Product in HP-HT Conditions

During production from sour gas reservoirs, precipitation of elemental sulfur can take place in production tubing, resulting in plugging of the well and stop of production. Injection in tubing of products devoted to dissolving sulfur can be an efficient solution for plug removal and production restoring. Traditionally, organic solvents (like toluene) are employed for solid sulfur dissolution. In the present work, experimental investigations have been performed on a particular innovative liquid product designed as active phase for wellbore injection or near wellbore applications. The analyses about the behavior of the considered product were conducted at HP-HT conditions. For this purpose, PVT laboratory equipment was employed, being able to reproduce the conditions of interest for the formation of elemental sulfur plug in well. An important preliminary optimization phase on the experimental setup was necessary to assure the correct management of studied liquid substance and solid sulfur. Integration of main outcomes with other kind of analyses allowed to depict a complete representation of the behavior: microscopy analysis of the liquid phase and high-resolution tomography of solid sulfur before and after the interaction were employed. A key point of the experimental characterization is the reproduction of significant involved phenomena. A preliminary effort was necessary for reproducing the realistic crystal form expected during the precipitation of solid sulfur in well. The dissolution efficiency of the liquid product is evaluated by observing its physical interaction with sulfur in a HP-HT cell. Particular attention was paid to correctly handling employed substances at the considered pressure and temperature conditions. A detailed description of the optimized equipment used in laboratory is provided. Several dissolution tests have been conducted at different temperature and pressure conditions, aiming to observe the dependence of the dissolution efficiency on the thermodynamic parameters. A visual qualitative analysis was performed on both the liquid product and the solid plug, before and after the interaction in cell. This allowed to deepen the comprehension of the dynamics of sulfur dissolution, which takes place not only from the top face of the plug, but also from preferential paths (fractures) present inside the plug itself. The presence of sulfur crystals dispersed in the liquid product after sampling from the cell is also evident at the end of the tests. The studied novel sulfur-dissolving liquid active phase is a candidate for remedial job injection at well in case of plugging due to solid elemental sulfur precipitation. The analyses here presented allowed to characterize the dissolution potential of this product. An optimized workflow was designed, including different kind of experimental disciplines.

Formulation and Evaluation of Ibuprofen Fast Dissolving Tablets Employing Starch Malonate (Modified Starch) as a Superdisintegrant

Aim: The goal of the study was to prepare a superdisintegrant named starch malonate followed by its evaluation for physicochemical properties. Prepared starch malonate was optimized in the preparation of fast dissolving tablets of ibuprofen by using 23 factorial designs. Methods: Compatibility studies like FTIR, TLC and DSC were performed to check any interaction between starch malonate and ibuprofen. Fast dissolving tablets were compressed by direct compression method and subjected to various official tests like hardness, friability, drug content, dissolution etc. Wetting time and water absorption ratio were also performed. At last response surface plot and contour plot was plotted to check the effects of starch malonate, croscarmellose sodium and crospovidone (independent variables) on disintegration time and dissolution efficiency in 5 minutes (dependent variables). Stability studies were also performed to check the stability of prepared fast dissolving tablets of ibuprofen. Results: Results of the studies showed that all the results are within acceptable limits and complying with the criteria of fast dissolving tablets. Drug content was found to be (100±5%), hardness of all tablets were found in between 3.8 -4 kg/cm2, friability was found less than 0.15%. Optimized formulation has showed less wetting time, less disintegration time followed by enhanced drug release. Among all formulation, formulation F2 has shown least disintegration time and enhanced drug release (99.89%) as compared to other formulations. We can conclude that starch malonate can be used as a novel superdisintegrant.

High-Temperature Stable Specific Enzyme for Guar Polymer Based Fracturing Fluid Degradation

Hydraulic fracturing, commonly referred to as fracking, is a widely used technology to enhance the productivity of low-perm reservoirs and the aqueous-based fracturing fluids use guar as the rheology builder. Residual polymer layer over the fractured surface results in a reduced matrix to fracture permeability, causing reduced well productivity. This research aims to develop a specialized mannanase enzyme and evaluate its efficiency in degrading linear and cross-linked guar polymer gel as a function of time, temperature, and breaker concentration, to enhance the effectiveness of the fracturing process and yielding higher production. The study begins with developing high-temperature stable mannanase using "protein engineering" tools to minimize denaturation at high temperatures and the underlying formation chemistry, followed by optimization of polymer, crosslinker, and breaker concentration through the measurement of rheological properties at moderate to high temperature. Initial studies were conducted using HT-HP filter press and filter papers as porous media for visual inspection of polymer cake dissolution efficiency. Final conclusions were drawn from the simulated coreflooding studies, wherein the injection and production return permeabilities were investigated on post-fracture and enzyme-treated cores, where the breaker was mixed with the frac fluid applied once the frac fluid is in place. The thermal stability of the enzyme breaker vis-à-vis viscosity reduction and degradation pattern of linear and cross-linked gel observed from the break test showed that the enzyme is stable up to 250 °F and can reduce viscosity by more than 1800 cp (99% breaking ability).

Additive Scale Removal Based on Noncorrosive Organic Acid for Handling Silica and Carbonate Scale in Oil and Gas and Geothermal Wells

The silica and carbonate scale that forms along the production pipeline is a significant problem in the oil and gas and geothermal industry because it disrupts production operations. Silica and carbonate scales on the inside of the pipe cause blockage of flow and an increase in pressure. Failure of downhole settlement equipment will reduce the production capacity of the well, and the maintenance burden will increase. The main objective of this research is to test the reactivity of an environmentally friendly non-corrosive organic acid system based on vegetable fatty acids and carbohydrates with high dissolution efficiency for the treatment of silica and carbonate scales in geothermal and oil and gas fields. This paper provides information on laboratory analysis in terms of analysis of the composition of scale samples obtained through XRD analysis, acid system developed testing for dissolution efficiency at 50°C and 100°C for 1 hour, compatibility and stability testing, and testing the corrosive impact on coupon metal AISI CS-1019 samples at 100°C for seven days in a closed aging cell. Testing the concentration of the new organic acid system in high dissolution efficiency and low corrosion effect was carried out through laboratory-scale studies before being applied to field-scale operations. The results showed that the dissolution efficiency of the scale sample against the developed organic acid system (100% concentration) at 50 and 100°C for 1 hour showed reactive effect. Reduction rate of silicate-07; silicate-29; silicate-L1; silicate-KB1; carbonate-A3 at 50°C were 7.825%; 3.823%; 6.177%; 2.014%; 8.211%, and at 100°C were 12.884%; 0.631%; 15.047%; 0.103%; and 32.909%. The newly developed organic acid system demonstrates stability and compatibility with formation waters with low formed solids, and it has a pH of 6. The results of the corrosion rate test were carried out without an inhibitor at 100°C for seven days and gave a yield of 77.340 mils per year, while other commercial additives gave a yield of 2,525.120 mils per year. The new eco-friendly organic acid system has a good effect in helping dissolve silica and carbonate scales, safe for production equipment, and lowers high maintenance costs. Keywords: Organic Acid Scale Remover, Silica and Carbonate Scale, Environmentally friendly

OPTIMIZATION OF STARCH GLYCOLATE AS NOVEL SUPERDISINTEGRANT IN THE FORMULATION OF GLIPIZIDE FAST DISSOLVING TABLETS THROUGH 23FACTORIAL DESIGN

Objective: To synthesize, characterize and evaluate starch glycolate as a superdisintegrant in the formulation of Glipizide fast dissolving tablets by employing 23 factorial designs. Methods: Starch glycolate was prepared and its physical and micromeritic properties were performed to evaluate it. The fast dissolving tablet of Glipizide was prepared by employing starch crotonate as a superdisintegrant in different proportions in each case by direct compression method using 23 factorial design for the evaluation of tablet parameters like disintegration and dissolution efficiency in 5 min. Results: The starch glycolate prepared was found to be fine, free-flowing and amorphous. Starch glycolate exhibited good swelling in water with a swelling index (10%). The study of starch glycolate was shown by fourier transform infrared spectra (FTIR). The drug content (100±5%), hardness (3.5–4 kg/sq. cm), and friability (<0.15%) was been effective with regard to all the formulated fast dissolving tablets employing starch glycolate. The disintegration time of all the formulated tablets was found to be in the range of 13±0.015 to 180±0.014 sec. The optimized formulation F8 had the least disintegration time i.e., 13±0.015 sec. The wetting time of the tablets was found to be in the range of 8±0.015 to 95±0.013 sec. The In vitro wetting time was less (i.e., 8±0.015s) in optimized formulation F8. The water absorption ratio of the formulated tablets was found to be in the range of 75±0.012 to 150±0.014%. The percent drug dissolved in the optimized formulation F8 was found to be 99.95% in 5 min. Conclusion: Starch glycolate was an efficient superdisintegrant for fast-dissolving tablets. The disintegration and dissolution efficiency of the fast dissolving tablets of glipizide was good and depended on the concentration of superdisintegrant employed i.e., starch glycolate, sodium starch glycolate, crospovidone. The formulated fast dissolving tablets of glipizide exhibited good dissolution efficiency in 5 min which can be used for the fast therapeutic action of glipizide.

Phospholipid-containing films for improved drug release

Phospholipids from natural sources can delay liquid-liquid phase separation and improve supersaturation for active pharmaceutical ingredients with poor water-solubility in aqueous media. Researchers have developed oral films containing phospholipids to enhance the dissolution efficiency of hydrophobic pharmaceutical ingredients. Phospholipid-based oral films provide an alternative approach for compounding pharmacies to formulate drugs with poor water solubility.

Dissolution profile of Curcumin from solid dispersion prepared at a high drug load of Curcumin using Poloxamer 407 as the carrier

Introduction: Curcumin, a BCS II drug, suffers from poor bioavailability. Increasing curcumin dissolution is a way to increase its bioavailability. Solid dispersion formulation can be used to improve curcumin dissolution. However, the successful curcumin solid dispersion is limited to a relatively low drug load (< 20%). Objective: This study aimed to investigate the dissolution behaviour of curcumin at a higher drug load (27.9%, 42.3%, and 56.6%) using a surfactant carrier of poloxamer 407. Methods: The solvent evaporation method was employed to prepare high drug load solid dispersion of curcumin. A physical mixture of the corresponding solid dispersion formulation was prepared as a control. Drug load, dissolution behaviour in 180 minutes, and dissolution efficiency (DE180) were determined. Results: The results showed that incorporating curcumin into a poloxamer 407 solid dispersion significantly improves the dissolution rate of curcumin. In the solid dispersion formula, the dissolution behaviour of curcumin was found to be carrier-dependent.

DESIGN, OPTIMIZATION AND EVALUATION OF ACECLOFENAC FAST DISSOLVING TABLETS EMPLOYING STARCH VALERATE–A NOVEL SUPERDISINTEGRANT

Objective: To synthesize, characterize and evaluate starch valerate as a superdisintegrant in the formulation of aceclofenac fast dissolving tablets by employing 23 factorial design. Methods: Starch valerate was synthesized and its physical and micromeritic properties were performed to evaluate it. The fast dissolving tablet of aceclofenac was prepared by employing starch valerate as a superdisintegrant in different proportions in each case by direct compression method using 23 factorial design for evaluation of tablet parameters like disintegration and dissolution efficiency in 5 min. Results: The starch valerate prepared was found to be fine, amorphous and free flowing. Starch valerate exhibited good swelling in water with swelling index (125.2%). The study of starch valerate was shown by fourier transform infrared spectra (FTIR). The drug content (200±5%), hardness (3.5–4 kg/sq. cm), and friability (<0.15%) has been effective with regard to all the formulated fast dissolving tablets employing starch valerate. The disintegration time of all the formulated tablets was found to be in the range of 14±0.04 to 25.7±0.02 sec. The optimized formulation F4 had the least disintegration time i.e., 12.8±0.02 sec. The wetting time of the tablets was found to be in the range of 76±0.21 to 217±0.17s. The In vitro wetting time was less (i.e., 28±0.02s) in optimized formulation F4. The water absorption ratio of the formulated tablets was found to be in the range of 46±0.12 to 100±0.27%. The percent drug dissolved in the optimized formulation F8 was found to be 99.93% in 5 min. Conclusion: Starch valerate, when combined with sodium starch glycolate, croscarmellose sodium, with aceclofenac, was found to be an effective super disintegrant which improved the dissolution efficiency and could therefore be used in the formulation of quick dissolving tablets to provide immediate release of the contained drug within 5 min.

OPTIMIZATION OF STARCH CROTONATE AS A NOVEL SUPERDISINTEGRANT IN THE FORMULATION OF FAST DISSOLVING TABLETS THROUGH 23 FACTORIAL DESIGN

Objective: To synthesize, characterize and evaluate starch crotonate as a superdisintegrant in the formulation of Piroxicam fast dissolving tablets by employing 23 factorial design. Methods: Starch crotonate was synthesized and its physical and micromeritic properties were performed to evaluate it. The fast dissolving tablet of Piroxicam were prepared by employing starch crotonate as a superdisintegrant in different proportions in each case by direct compression method using 23 factorial design. Results: The starch chrotonate prepared was found to be fine, free flowing and amorphous. Starch crotonate exhibited good swelling in water with swelling index (50%). The study of starch crotonate was shown by fourier transform infrared spectra (FTIR). The drug content (100±5%), hardness (3.6–4 kg/sq. cm), and friability (<0.15%) have been effective with regard to all the formulated fast dissolving tablets employing starch crotonate. The disintegration time of all the formulated tablets was found to be in the range of 18±03 to 66±03 sec. The optimized formulation F8 had the least disintegration time i.e., 18±03 sec. The wetting time of the tablets was found to be in the range of 49.92±0.11 to 140±0.18s. The In vitro wetting time was less (i.e., 74±0.37s) in optimized formulation F8. The water absorption ratio of the formulated tablets was found to be in the range of 27.58±0.01 to 123.07±0.33%. The percent drug dissolved in the optimized formulation F8 was found to be 99.83% in 10 min. Conclusion: Starch crotonate, when combined with sodium starch glycolate, croscarmellose sodium, with Piroxicam was found to be an effective super disintegrant which improved the dissolution efficiency and could therefore be used in the formulation of quick dissolving tablets to provide immediate release of the contained drug within 10 min.

Results of experimental studies of integrated physico-chemical impact in carbonate reservoirs

The article highlights the experimental studies results of carbonate rock dissolution kinetics in order to develop effective methods of slowing down the acid reaction rate in the heterogeneous structures. It was found that the intensity of carbonate reservoirs leaching process with the addition of hydrocarbon solvents such as dioxanes increases due to the acetals transition to the oil phase, dissolution of highly active oil components and more intense penetration of an aqueous solution of hydrochloric acid to the carbonate matrix of the reservoir rock, which intensifies the process of leaching. The technology of complex physico-chemical impact on carbonate reservoirs has been developed. It is shown that the use of a aqueous hydrochloric acid solutions mixture and an organic solvent leads to an increase in the dissolution efficiency to 88% and the reaction rate increases by a factor of 3.5.