Ilmenite Inclusion: A Solution towards Solid Sagging for Hematite-Based Invert Emulsion Mud

The sagging tendency of hematite in drilling mud is a common challenge occurring at high-pressure and high-temperature (HP/HT) applications. This work studies the performance of hematite-based invert emulsion mud for HP/HT conditions and provides a solution to prevent the hematite settlement using a combination of ilmenite with hematite. Practical mud formulation was utilized over a range of ilmenite/hematite ratios (0/100, 20/80, 40/60, and 50/50%) to study sagging behaviour. From the sag tests, the optimum combination proportion was determined. Thereafter, the density, emulsion stability, rheological and viscoelastic properties, and filtration conduct for the formulated mud were evaluated. The experiments were conditioned as per the standards of the American Petroleum Institute. The obtained results of sagging experiments indicated that including 50% of ilmenite mitigated the hematite settling and reduced the sag tendency towards the safe range. A slight drop (4%) in mud weight was noticed upon adding the ilmenite, whereas the emulsion stability was enhanced from 551 to 574 volts with the 50% ilmenite content. The rheology and viscoelasticity measurements showed that 50/50% combination improved the yield point (YP) by 50% with a trivial 1 cP increment on plastic viscosity (PV), hence enhancing the YP/PV ratio by 46%. Also, the gelling strength was enhanced resulting in flat rheology and better gel structure. The filtration behaviour of 50% ilmenite mud was improved compared to blank hematite as it resulted in 21, 15, and 17% reduction on the filtrated volume, filter cake weight, and thickness, respectively. This study provides a solution for hematite sagging issue at HP/HT using combined weighting agents, which contributes to enhancing the mud stability and avoiding several well control issues and related operational and technical challenges that eventually will economize the drilling cost and time.

Use Of Sugarcane Biomass In Brazil

Recently, the use of biomass energy has been growing worldwide on an accelerated trajectory, with the prospect of staying among the main renewable energy sources for the coming decades, along with wind and solar energy. Brazil is the largest producer of sugarcane on the planet and the second-largest producer of ethanol. But in addition to sugar, first-generation ethanol, and vinasse (for ferti-irrigation), other by-products and process residues from the plants (such as bagasse, filter cake, vinasse, straw, and sugarcane tip) can be used for the production of thermal and electric energies and also second-generation ethanol and biogas fuels. In this context, this paper presents the current scenario of sugarcane biomass in Brazil, discussing issues involving the use of sugar-alcohol by-products for bioenergy and biofuel production. Furthermore, a study on the reuse of sugarcane bagasse fibers for the production of eco-composite material is also presented. Finally, the concepts of biomass energy are described from a bibliographic survey and the previous experiences of the authors.

A review of the various treatments of oil-based drilling fluids filter cakes

Treatment of the filter cake layer after drilling is essential for better cement integrity and to retain the original reservoir permeability. Compared to water-based filter cake, oil-based mud filter cake removal is more sophisticated as oil encloses the filter cake’s particles. Therefore, oil-based mud clean-up requires wettability alteration additives (mutual solvents and/or surfactants) for permitting acid/filter cake reaction. With an appropriate acid, microemulsions were reported to be very efficient in cleaning oil-based filter cakes, due to their low interfacial tension and high acid solubility. The objective of this paper is to provide an overview of the different techniques and treatment solutions utilized in oil-based filter cake clean-up. Furthermore, a synopsis of the various treatments for drilling fluids densified with different weighting materials is presented. Subsequently, the research limitations and opportunities have been highlighted for future work. In the light of the review that has been presented in this paper, it's recommended to conduct further investigation on some areas related to filter cake removal. The removal of filter cake formed from weighting materials other than barite, calcium carbonate, ilmenite, and manganese tetroxide needs to be investigated thoroughly. Additionally, the overall efficiency of oil-based mud removal needs to be studied under wide ranges of temperature, salinity, and pH. The utilization of surfactant-free microemulsions in filter cake treatment could also be investigated.

Chemical and technological attributes of sugarcane as functions of organomineral fertilizer based on filter cake or sewage sludge as organic matter sources

Sugarcane is one of the main alternative sources of biomass for the biofuel sector, and its large-scale production has considerable environmental impact. Organomineral fertilizers formulated with potential environmental contaminants, such as filter cake and sewage sludge, positively influence plant growth and development. The objective of the present study was to evaluate the chemical and physical characteristics of sugarcane fertilized with pelletized organomineral fertilizers based on filter cake or sewage sludge. Eight field treatments were applied, based on three organomineral fertilizer compositions (50%, 100%, and 150%) associated with two organic matter (OM) sources (filter cake or sewage sludge), in addition to a control with 100% mineral fertilizer application, and a no-fertilization control (0%). Sugarcane attributes were evaluated during two consecutive harvests. The weights of stalks per hectare (ton ha-1), sugarcane productivity (ton ha-1), quantity of sugar per hectare (TSH, ton ha-1), and physicochemical properties of sugarcane juice (pol [%], Brix [%], purity [%], and fiber [%]) were evaluated. There were no significant differences in the attributes between OM sources or organomineral fertilization treatments and the exclusive mineral fertilization. The organomineral fertilizer application rate recommended for maximum quantitative and qualitative sugarcane in the first sugarcane harvest was between 2 and 9% above the regular recommendation for mineral fertilizer, regardless of the OM source. In the second harvest, the sewage sludge source increased total sugar and sugarcane per hectare by 4.68 and 4.19%, respectively, compared to the sugarcane filter cake source. Sewage sludge and sugarcane filter cake are viable alternatives for organomineral composition and could improve economic returns and minimize negative environmental impacts in sugarcane cultivation systems.

Minimization of Ultra-High Temperature Filtration Loss for Water-Based Drilling Fluid with ß-Cyclodextrin Polymer Microspheres

Due to the rapid degradation of conventional biopolymer or synthetic polymeric additives at high temperature (HT) or ultra-high temperatures (ultra-HT), effective control of water-based drilling fluid filtration in HT or Ultra-HT environment is still a great challenge in drilling operation. β-cyclodextrin polymer microspheres (β-CPMs), generally using for drug release and waste water treatment, are evaluated as environmentally friendly ultra-HT filtration reducer. The impact of the microspheres on water-based drilling fluids’ properties including rheology and filtration prior to and after hot rolling at different temperatures ranging from 120 to 240°C was investigated. The high temperature and high pressure (HTHP) filtration properties of the microspheres compared to several commercial high temperature filtration reducers were conducted according to the API recommended procedures. The filtration controlling mechanism was analyzed from zeta potential measurement, particle size distribution measurement, and scanning electron microscope observation of filter cake. The results indicated that the β-CPMs exhibited peculiar filtration behavior differently from conventional additives. When the hot rolling temperature was below 160℃, β-CPMs performed a 30% filtration reduction at 1 w/v% content in comparison with control sample. Once the hot rolling temperature was above 160℃, the capacity of filtration control was further improved with increasing temperatures. This is contrast with conventional filtration reducers that the filtration control capacity deteriorate with increasing temperatures. The microspheres still exhibited superior filtration control after exposure to 240℃. Furthermore, β-CPMs showed little effect on the drilling fluid's rheology. When the temperature was below 160℃, the filtration reduction was obtained by water absorption and swelling of β-CPMs. When the temperature was above 160℃, hydrothermal reaction occurred for β-CPMs. Numerous micro- and nano-sized carbon spheres formed, which bridge across micro and nanopores within filter cake and reduce the filter cake permeability effectively. When the temperature was higher than 160℃, hydrothermal reaction occurs. Carbon spheres generated by the hydrothermal degradation of the β-CPMs, which are responsible for the effective filtration control. The hydrothermal reaction changes the adverse effect of high temperature into favorable improvement of filtration control, which provides a novel avenue for HT and ultra-HT filtration control. The β-CPMs show potential application in deep well drilling as environmental friendly and high temperature filtration reducers.

Associative Microgels, New Self Adaptive Systems to Control Fluid Loss in Well Cementing

Fluid loss control additives are critical constituents in a cement slurry formulation to ensure even cement placement and ultimately satisfactory zonal isolation. Many technological options have been developed over the past decades to design fluid loss control additives for cementing. The most popular technologies as of today are either based on water soluble polymers or colloidal particles like latexes. As an alternative approach, in this paper we introduce a new technology based on associative or "sticky" microgels. These microgels are able to associate with one another at elevated concentration but, more surprisingly, are also able to associate under shear in the dilute regime during a filtration process. As a consequence these additives demonstrate outstanding performance as fluid loss control agents. This study focuses first on standard API filtration tests using sticky microgels, and on how their behavior in application differs from traditional systems, in particular water-based soluble polymers such as cellulosic derivatives or synthetic polymers. Our investigations then focus on the working mechanism of the microgel system by analyzing adsorption on the cement surface, rheology, and filter cake structure using Mercury Intrusion Porosimetry (MIP). Finally the behavior of sticky microgels in model filtration tests is explored with either filtration against porous ceramic discs or using microfluidic chips allowing a direct visualization of microgels during filtration. This study demonstrates that associative microgels are not controlling fluid loss through a simple size match between particles and pores within the filter cake but rather through shear-induced aggregation. Microfluidic observations reveal that aggregation occurs irreversibly as microgels are forced through the pores as the filtration process occurs. The shear-induced associated gels are particularly effective at reducing dramatically the filter cake permeability and allowing gas migration control. Interestingly the shear-induced aggregation of associative μgels seems to confer self-adaptive properties of the fluid loss additives with respect to the pore network to be clogged. Indeed, formation of shear aggregated gels larger than the individual microgels can be used to limit fluid loss even if the pore sizes are much larger than the individual microgels.

Tensile Failure and Fracture Width of Partially Permeable Wellbores with Applications in Lost Circulation Material Design

Summary Estimation of near-wellbore fracture widths remains central to designing the particle size distribution (PSD) and composition of lost circulation material (LCM) blends. Although elastic rock models are often used for this purpose, they fall short in capturing the substantial effect of pore fluid pressure on the fracture width. The problem is addressed in this paper by incorporating the poroelastic back stress in width estimation of axial fractures nearby an inclined wellbore. The poroelastic back stress is caused by a nonideal drilling fluid filter cake allowing for fluid pressure communication between the wellbore and pore space of the rock surrounding the wellbore. In this aspect, a proper definition of the filter-cake efficiency is made in terms of the wellbore pressure, far-field pore fluid pressure, and pore fluid pressure of the rock surrounding the wellbore. The value of this parameter is estimated from the standard drilling fluid filtration test results, as well as the formation rock permeability. The filter-cake efficiency is next used to develop the long-time, asymptotic analytical solution for the poroelastic stress of an inclined wellbore. By accounting for the obtained poroelastic back stress, an improved estimation of the wellbore tensile limit that depends on the filter-cake efficiency parameter is developed. For wellbore pressures beyond the wellbore tensile limit, the width of the near-wellbore fractures is estimated. The fracture width estimation is made through an analytical, dislocation-based fracture mechanics solution to the integral equation describing the nonlocal stress equilibrium along the fracture faces. The commonly practiced scheme for geometric design of LCM blends is enhanced by using the presented improvement in estimation of the near-wellbore fracture width. A case study is used to demonstrate the substantial effect of drilling fluid filtration properties and the resulting poroelastic back stress on the wellbore tensile limit, estimated fracture width, and consequently, composition of the recommended LCM blend.

Application of Cellulosic Fibrous Material from Agro Waste as Filtrate Loss Modifier in Aqueous Mud-Morphology at HTHP Conditions

Controlling the filtration characteristics of any drilling fluid does not only include the control of the filtrate volume penetrating into the formation; but also the ability of the mud to deposit a thin low-permeability filter cake on the wall of the wellbore quickly. The permeability of the filter cake is very dependent on the particle size because when small size particles are used, the permeability decreases, because of the fact that colloidal particles get packed very tightly. This study investigated the filtration and filter cake characteristics of water-based mud (WBM) using fibrous cellulose from Tiger Nut waste and the guar gum. American Petroleum Institute (API) Recommended Practice Standard Procedure for Field Testing Drilling Fluids, API RP 13B-1 was applied during the analysis. Statistical analysis of the experimental data was conducted and the R2 value (0.99) showed that the experimental method adopted was replicable. Mud samples B2 and C2 gave an optimum result and their mud cakes developed under High-Temperature High-Pressure (HTHP) condition were dried and further analyzed with scanning electron microscope (SEM). The results showed that the filter cakes SEM structure for cellulosic fibrous from agro waste and guar gum exhibits similar characteristics; and the mud cakes was firm after soaking with 15% HCl for thirty minutes but started dissolving after one hour. The SEM analysis inferred that the filter cake morphology shows a good particle-pore interlocking for sample C2 than B2.