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Innovative Manganese Tetroxide/CaCl2 Water-Based Drilling Fluids for HP/HT Wells

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Calcium carbonate (CaCO3) has been used to make high-density drilling muds. However, when drilling 5⅞-in. hole, sticking occurs because of the high concentration of CaCO3 required. To minimize sticking, barite (BaSO4) is added to reduce the amount of solids needed. However, barite is damaging because it does not dissolve in commonly used acids. Drilling fluids have been developed at a wide range of densities using calcium chloride (CaCl2) salt with manganese tetroxide (Mn3O4). The small particle size, spherical shape, and high specific gravity of Mn3O4 make it good weighting material to reduce solids loading and settling compared with CaCO3 and BaSO4.

Introduction

Several factors need to be considered when designing drilling fluids. For example, formation permeability determines filtration characteristics. Temperature- or water-sensitive formations determine the type of polymer and type of drilling fluids needed. Important considerations in designing drilling fluids include rheological properties to provide good carrying capacity and minimum filtration control loss.

Different polymers are used for filtration control, viscosity modification, and shale stabilization. Different types of polymers can provide different performances in rheology and filtration. Some polymers, such as xanthan gum and starch, lose viscosity at high temperatures because of degradation and instability at harsh conditions. Some polymers are not effective in salt solutions because salt inhibits hydration of polymers, affecting their functions. Other polymers are less sensitive to salt drilling fluids. Polymer compatibility with drilling fluids is important to achieve good suspension, rheology, and filtration control to ensure good hole cleaning and less formation damage.

Designing drilling fluids depends heavily on the selection of the suitable size of weighting materials that will work as bridging materials as well. Once the solids invade the formation, they cannot be removed by natural flow.

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 169315, “Innovative Manganese Tetroxide/CaCl2 Water-Based Drilling Fluids for HP/HT Wells,” by Abdullah S. Al-Yami, SPE, Abdullah Al-Nimer, SPE, Abdulaziz Bubshait, SPE, Omar Al-Fuwaires, SPE, and Ali Al-Wabari, SPE, Saudi Aramco, prepared for the 2014 SPE Latin American and Caribbean Petroleum Engineering Conference, Maracaibo, Venezuela, 21–23 May. The paper has not been peer reviewed.
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Innovative Manganese Tetroxide/CaCl2 Water-Based Drilling Fluids for HP/HT Wells

01 November 2014

Volume: 66 | Issue: 11

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