Browse Prior Art Database

Improved GeoBalance Barrier Pill Part II

IP.com Disclosure Number: IPCOM000240641D
Publication Date: 2015-Feb-13
Document File: 5 page(s) / 387K

Publishing Venue

The IP.com Prior Art Database

Abstract

The use of a high-density “mud cap” tripping pill to provide sufficient hydrostatic pressure down-hole for appropriate well control is a common practice on Managed Pressure Drilling (MPD) and Underbalanced Drilling (UBD) Operations. However, placing a high-density tripping fluid on top of a lower density drilling fluid often results in large volumes of the two fluids commingling/mixing and requires corrective action to achieve a constant fluid density through the system before drilling ahead. Weighting up or increasing the viscosity of the drilling fluid before tripping are options but introduce several disadvantages that have resulted in greater cost, lost rig time, increased risk of formation fracture, and the need for additional storage capacity. The potential new formulation material: A processed waste stream from oil based drilling fluids. A solids laden drilling fluid with high (>10%) low gravity colloidal solids is subjected to the removal of water until approximately 1-2% water remains. The resultant oily product (Sludge) has highly thixotropic flow properties that make it suitable as a geo-balance pill for water based fluid applications. Successful laboratory GBP placements/barrier tests were performed with various water-based and oil-based fluids. In the water based cases, it was possible to keep a 10.2 ppg drilling fluid separated from an 18 ppg high-density “mud cap” tripping pill.

This text was extracted from a Microsoft Word document.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 27% of the total text.

Improved GeoBalance Barrier Pill Part II

Jessica Paola Ramirez Angulo

William Walter Shumway

Timothy N. Harvey

Introduction

The use of a high-density “mud cap” tripping pill to provide sufficient hydrostatic pressure down-hole for appropriate well control is a common practice on Managed Pressure Drilling (MPD) and Underbalanced Drilling (UBD) Operations. However, placing a high-density tripping fluid on top of a lower density drilling fluid often results in large volumes of the two fluids commingling/mixing and requires corrective action to achieve a constant fluid density through the system before drilling ahead.

Weighting up or increasing the viscosity of the drilling fluid before tripping are options but introduce several disadvantages that have resulted in greater cost, lost rig time, increased risk of formation fracture, and the need for additional storage capacity.    

The potential new formulation material: A processed waste stream from oil based drilling fluids. A solids laden drilling fluid with high (>10%) low gravity colloidal solids is subjected to the removal of water until approximately 1-2% water remains. The resultant oily product (Sludge) has highly thixotropic flow properties that make it suitable as a geo-balance pill for water based fluid applications. Successful laboratory GBP placements/barrier tests were performed with various water-based and oil-based fluids. In the water based cases, it was possible to keep a 10.2 ppg drilling fluid separated from an 18 ppg high-density “mud cap” tripping pill.

Traditional Method and Issues

The drilling fluid used for MPD operations is of a lower density than that required for normal Overbalanced Drilling. This means that the Hydrostatic Pressure from the drilling fluid is lower than the formation pore pressure; when circulating through the surface choke equipment back pressure is applied to control the actual bottomhole pressure at the desired level.  Because of this, when static, a hydrostatic overbalance is required when tripping to avoid a kick. This is often accomplished by using a high density mud cap on top of the underbalanced drilling mud, resulting in the desired total bottomhole Hydrostatic Pressure. The major shortcoming of the mud cap design is the risk of comingling of the costly mud cap with the drilling fluid beneath it, contaminating both.

This contamination can result in undue and excessive operational delays as both fluids must be circulated and conditioned back to specifications. The contaminated portion of the lighter drilling fluid may be isolated and captured for disposal. This also increases the costs related to the use and cleaning of additional trucks and tanks to transport and store the material, and the associated costs for proper disposal.

Current technology often relies on a casing Fluid Loss Control Valve (FLCV) to isolate the exposed formations from the upper wellbore. Unfortunately, the FLCV technology has a poor performance history, and a...