A Significant MWD Tool Signal Strength Improvement: Another Advantage of Using a Treated Micronized Barite Drilling Fluid System

Abstract

An order of magnitude increase in the Measurement While Drilling (MWD) signal strength was achieved while using a treated micronized barite (TMB) drilling fluid system. The MWD transmits downhole data critical for real-time data acquisition, geosteering, and formation evaluation.The MWD signal strength is one of the core variables that must be considered when drilling wells with increased measured depth. By displacing the conventional drilling fluid with the TMB System, the Acquisition System was able to recognize a ten-fold increase in signal strength from 0.1-0.2 psi to 1-2 psi. In addition, a 50% torque reduction was recorded and barite sag was not an issue. These performance characteristics make the TMB system a viable candidate for drilling high inclined wellbores and other critical wells.This paper covers a successful field trial showing the comparable MWD signal strength data with a treated micronized barite drilling fluid system carried out in the 8½-in. section of an HTHP exploration well offshore Brazil. IntroductionWith the ever increasing need to drill wells deeper and more pressure and temperature challenges, it is becoming crucial to have a drilling fluid system that can handle these adverse conditions. However, the drilling environment includes not only adverse downhole conditions, but also the fluid and equipment that must work in harmony. Drilling fluids must not only provide the necessary properties to manage the downhole conditions (e.g., prevent fluid influxes, promote wellbore stability), but also assist the functions of the drillstring and tools (e.g., cool and lubricate the bit, carry cuttings out of the hole).A common part of drilling fluid is the weight materials which are used to increase the density of drilling fluids and control subsurface wellbore pressures in many wells. Ground barite, a dense mineral, is the most common choice of weighting agent, especially for wells requiring higher mud weights. For a drilling fluid density of 2.0 g/cm 3 (16.7 lb/gal), 33 to 35 vol% of the drilling fluid is barite (Prebensen et al. 2009a). At this high loading level, the impact of barite on the rest of the drilling operation is important.A critical issue with API-grade barite and alternative high density weighting agents is their propensity to settle and separate from the fluid. Treated Micronized Barite (TMB) was designed to mitigate this sag. The extremely small particle size of TMB in which the majority of particles are less than 2 microns diameter, enables low-rheology non-aqueous fluids (NAF) to be formulated with considerably reduced risk of barite sag and settlement compared to fluids formulated with APIgrade barite which can be up to 75 microns in size (Taugbøl et al. 2005).

Nanomaterial-Based Drilling Fluids for Exploitation of Unconventional Reservoirs: A Review

“…(1) Using treated micronized barite (TMB), which is significantly smaller than regular API barite (2 micron as compared to <75 micron) to reduce the potential of sag of barite [112]. Benefits of TMB are: improvement of ECD management in narrow hydraulic operating margin (reducing the pump pressure for the same ECD and reducing the risk of ECD induced losses), improvement in pressure while drilling (PWD), logging while drilling (LWD) and measurement while drilling (MWD) signal, and reduced swab, surge, and circulating pressure [113]. (2) Replacing barite with a new weighting agent that is heavier than barite, more stable at high temperature, and can address the ECD challenges at reasonable cost [114].…”