The impact of weighting materials on carbonate pore system and rock characteristics

Abstract

The infiltration of the drilling fluids into the drilled formation causes significant alterations in the rock properties due to the interaction between the drilling fluid and the rock pore system. The objective of this study is to evaluate the impact of the most common weighting materials used in water‐based mud (WBM) on carbonate pore system and rock characteristics. Rock‐mud interaction was imposed by using a customized high‐pressure high‐temperature (HPHT) filtration test cell under 2068 kPa differential pressure and 93°C temperature to simulate downhole conditions. For filtration properties, ilmenite WBM showed the maximum values (10.9 cm3 filtrate volume and 8.7 mm thickness), while baryte recorded the lowest filtrate volume (6.2 cm3) and thickness (4.2 mm). Nuclear magnetic resonance (NMR) profiles illustrated the changes in the rock pore system due to two aspects: precipitation and dissolution. A general porosity reduction was recorded with all formulations, namely 7.5% and 10.1% for hematite and ilmenite, respectively. The rock permeability showed severe damage after mud exposure that caused the rock average pore size to decrease from macro to meso‐porous. After the mud invasion, the rock electrical resistivity showed alterations with all drilling fluids. Compressional wave velocities (Vp) showed an increasing trend that ranged from 2.52% increase for baryte‐WBM to 6.35% increase by Micromax‐WBM. A general reduction was found for shear wave velocities (Vs) after mud exposure, Micromax‐WBM showed no changes in Vs, while hematite and ilmenite showed the largest decreases of 6.71% and 5.56%, respectively.

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

“…A similar sequence was followed for sandstone formation in ref , which was used for comparison. A detailed description of the tests and equipment used are available in refs and .…”

“…The chemical composition in terms of the elemental analysis by X-ray fluorescence spectroscopy for the weighting materials is shown in Table . The main elements from the mineralogy perspective for Micromax are manganese (Mn), iron (Fe) and titanium (Tn) for ilmenite, and barium (Ba) and sulfur (S) for barite, while hematite consists mainly of iron. , The shape of the weighting agent’s particles was determined using a high-resolution SEM image. The results are shown in Figure .…”

“…The utilized core samples are sandstone and carbonate with different properties for each type, and the weighting materials used include barite, hematite, ilmenite, and Micromax. This work is an extension of the work of Gamal et al , focusing on the filter cake properties in carbonate and comparing the role of the formation properties in filter cake properties with different weighting materials. The investigated filter cake properties include filter cake thickness, porosity, permeability, and filtration volume.…”

“…Different studies were conducted to assess the impact of the different weighting materials on the formation characteristics. Gamal et al studied the change in the pore system and the rock characterizations for sandstone and carbonate formation. , They used barite (BaSO 4 ), Micromax (Mn 3 O 4 ), ilmenite (FeTiO 3 ), and hematite (Fe 2 O 3 ) as weighting materials. Moreover, Bageri et al investigated deeply the effect of the same weighting materials on mud rheology and the filtration properties for the sandstone .…”

Preface for the Special Issue Honouring Professor Hisham Nasr‐El‐Din

“…The Canadian Journal of Chemical Engineering is acknowledged for dedicating this special issue to the living memory of Dr. Nasr‐El‐Din. This acknowledgment is also extended to the authors who contributed to this special issue [ 1–28 ] as well as the guest editors:…”