The Role of Drilled Formation in Filter Cake Properties Utilizing Different Weighting Materials

Primary Investigation of Barite-Weighted Water-Based Drilling Fluid Properties

Drilling fluid is a critical component in drilling operation due to its various functions. It consists of many elements, and one of the main components is the weighting material which controls the mud density. The weighting material type and concentration have a significant impact on the drilling fluid properties. A common weighting material used in the oil and gas industry is barite. In this work, the impact of barite concentration on water-based drilling fluid was evaluated. The investigated drilling fluid properties are density, pH value, filtration behavior, and rheological parameters. An intense investigation was carried out to evaluate the impact of barite concentration on the filtration and filter cake sealing properties. The density and pH values were measured at room temperature, filtration test was performed at room temperature, and differential pressure was equal to 100 psi. The rheological parameters were determined after hot rolling for 16 h at a temperature of 250 °F. The results showed that both the density and pH value increased linearly with barite dosage. The filtration volume, filter cake thickness, and permeability increased with the incremental increase in barite dosage, and the exponential relationship was the best in describing the relation with barite concentration. However, the filter cake porosity had an inverse proportional relation with barite dosage. In the case of rheological properties, all the investigated properties including the plastic viscosity, yield point, ratio of yield point to plastic viscosity, and gel strength at two different times (i.e., 10 s and 10 min) increased in general as the barite concentration increased.

Innovative Applications of Red Mud: Converting an Environmental Challenge to a Drilling Asset

Red mud is generated from alumina production through bauxite digestion with caustic soda. Ma'aden aluminum production estimated the abundance in a million tons as 2.65:1:2 for bauxite, alumina, and red mud, respectively. The real challenge when it comes to red mud pertains to storage capacity; many solutions have been put forward in different industries, and in this study, the utilization of the red mud waste material is presented as a potential weighting material that could be incorporated into the design of drilling fluid systems. This study provides an assessment of the utilization of red mud as a drilling fluid, and it provides directions for the use of red mud in drilling mud systems as a filtration agent and as a finely divided solid used as a weighting material to increase the density of a given drilling fluid system. This study investigates the viability of red mud as an effective additive to drilling fluid and its effect on rheology and filtration. Different techniques are employed in red mud characterization and performance evaluation. The study assesses red mud as an inert solid in a drilling fluid system by investigating the drilling fluid rheology, apparent viscosity (AV), plastic viscosity (PV), and yield point (YP) before and after hot rolling at 150 °F, in addition to filtration properties under low-pressure, low-temperature and higher-pressure, higher-temperature conditions (at 150 °F and a differential pressure of 250 psi). Also, the study highlights the red mud solid characterization, material preparation, and acid dissolution at 150 °F. This study attempts to view the red mud situation from a practical application angle (primarily in the oil and gas industry). Test results show stable drilling mud fluid properties when utilizing red mud solid additives as weighting agents. The drilling mud exhibits relatively low plastic viscosity, gel strength, excellent sag behavior, and reasonable filtration control, even under HPHT conditions in aqueous-based fluids. The material dissolves in acid. Accordingly, red mud provides a viable option for weighting agents and filtration control.

Improving the filtration properties for manganese tetroxide mud utilizing perlite particles to drill wide-range permeability sandstone formation

A required feature of any drilling formulation is to mitigate the formation damage by having an excellent filtration and filter cake properties. The key factor for preventing and limiting formation damage is to improve the sealing qualities of the planned drilling fluid. In this study, a new novel filtration agent called "perlite" was introduced for improving the manganese tetroxide mud cake ability for better sealing features. The perlite particles were loaded to formulation containing the manganese tetroxide as weighting agent. The water-based drilling mud was designed at high densities (14.25 and 17.2 ppg). Perlite was added in varied concentrations to reach the optimum performance. The filtration test conducted at reservoir temperature of 250 °F and a differential pressure of 300 psi to form the filter cake. The tests were performed using sandstone cores with two different permeability categories (low and high permeabilities) as the filtration media. This gave the full picture of perlite performance as implemented for different formation properties and considering the drilling fluid properties. The formed filter cake structure and chemical composition was evaluated using scanning electron energy-dispersive X-ray (SEM-EDS). The presented results illustrated how the perlite was compatible to be added to the manganese tetroxide weighting agents in the same formulation. In addition, it has the capacity to improve the filter cake's sealing qualities, lowering the filtration volume by 41% and the filter cake internal and external layers permeability by 58% and 25%, respectively. Moreover, the EDS analysis showed that the perlite particles are concentrated generally in the internal layer of the filter cake.

Minimizing the Barite Scale in Carbonate Formations during the Filter Cake Removal Process

The barite scale is one of the most common scales in the oil and gas industry. It can form in the reservoir or precipitate in different production equipment. The formation of such a scale will significantly minimize the capillary diameter of the flow channels and consequently shrink the well productivity. On the other hand, the production of movable barite particles causes severe erosion for the installed equipment. There are several sources of the barite scale such as mixing of incompatible brines and solid invasion of the barite weighted during drilling. In addition, the barite scale could be produced during the interaction of the chelating agent solutions with the reservoir formation during the filter cake removal process (secondary damage). The main focus of this study is to prevent the barite scale inside the carbonate formations during filter cake removal. The capability of a solution consisting of both diethylenetriamine pentaacetic acid (DTPA) and ethylenediamine tetraacetic acid (EDTA) as a novel solution to prevent barite scale formation in carbonate formations after the removal of the barite filter cake was evaluated. A series of laboratory experiments were accomplished to characterize the barite scale and evaluate the performance of the proposed solution. In particular, particle size distribution, scanning electron microscopy, X-ray diffraction, core flooding, NMR spectroscopy, solubility test, and inductively coupled plasma (ICP) spectroscopy tests were conducted for this aim. The experiments were performed using carbonate core samples. The results showed that the proposed solution was able to load 35 000 ppm barium in the presence of calcite ions. The addition of EDTA tended to inhibit the barite deposition and improve the rate of the calcite reaction. NMR results showed that a mixture of DTPA and EDTA (20%) can stimulate the macropores, resulting in an increase in the return permeability by 1.4-1.8 times of the initial value, while the precipitation that occurred in the micropores could be ignored with respect to the overall porosity improvements.

The role of overbalance pressure on mud induced alteration of sandstone rock pore system

Overbalance pressure is a very critical parameter in drilling operations. It has a great impact on formation damage, depending on other downhole parameters such as temperature, time, type and composition of mud, and rock mineralogical content. The objective of this study is to determine the degree of the impact of overbalance pressure on mud-rock interaction and the resultant effects on the rock pore system. This research presents an experimental study for the interaction of a Berea Buff sandstone and barite water-based under different overbalance pressure (300, 700, and 1000 psi) under the same temperature and interaction time. The experiments involved the use of the scanning electron microscope and nuclear magnetic resonance relaxation measurements to monitor changes in the pore system of the rock samples. A modified filtration cell was used to accommodate the rock samples and mud at different overbalance pressures. The obtained results showed that the filtration properties, rock flow characteristics (rock permeability, pore throat radius, and pore system scale type) are all affected by increasing the overbalance pressure. The filtration properties increased in terms of mud cake thickness and filtrate volume by 111% and 36% respectively when the overbalance pressure was increased from 300 to 1000 psi. The total rock porosity showed a decrease from 21.6% (pre-mud interaction) to 17.6, 15.2, and 14.2% under 300, 700, and 1000 psi, respectively. The rock permeability decreased by 75% under 1000 psi overbalance pressure while pore throat radius decreased by 45%. However, the rock pore type remains on the same scale (Macro) after interaction with the mud. Statistical analysis showed that the rock porosity and permeability decreased with the overbalance pressure increase through a polynomial relationship with a high determination coefficient of 0.99. Analysis of the internal pore system by the scanning electron microscope showed that the formation damage is mainly attributed to the precipitations of mud solids as overbalance pressure is increased.