Systematic Approach to the Design and Application of a Well-Fracturing Fluid To Ensure Deepwater Production

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractAs deepwater exploration projects in the Gulf of Mexico and other offshore areas have gained momentum, development activities in all areas of drilling, completion and production of these wells have faced significant challenges. One key area of concern in completion of these wells is the design, application and compatibility of the fracturing fluid to ensure optimum well performance. Deepwater engineering design and application of fracturing fluids are presented with some unique challenges in well depths that can exceed 20,000 ft with pore pressures greater than 20,000 psi. One major issue facing deepwater fracturing is generating enough bottomhole treating pressure to create a hydraulic fracture at the sandface without exceeding the limitations of the hydraulic equipment at the surface. In order to overcome these surface hydraulic equipment limitations and still create the needed hydraulic fracturing pressure at the sandface, weighted fracturing fluid formulations have been developed to address these issues. Furthermore, due to the increased travel distance to the sandface and the extreme temperature ranges that the fluid is exposed from the mudline to the BHT, the fracturing fluid must have flexibility to be designed to meet specific density, extended crosslink delay times, friction pressures, and compatibility specifications.This paper summarizes a study to formulate a sodium bromide weighted, delayed crosslink fracturing fluid system to meet the fluid and engineering guidelines for the fracturing application. After baseline fluid formulation studies with the weighted sodium bromide, delayed crosslink fracturing fluid system were designed, rheological performance with breakers at BHT were run, stacked cell regained conductivity lab measurements were performed and friction pressures were determined. Additional studies were also conducted with this weighted fracturing fluid to determine compatibility with the well's produced crude oil and returned permeability studies utilizing formation cores.

A Weighted Fracturing Fluid System for Deep Well Stimulation Treatment

“…At 25 ℃, density of inorganic salt aqueous solution increases with quantity of weighted agent added. When quantity of NaBr added is reach up to 46% and NaCl is up to 4% , the density of inorganic salt aqueous solution is 1.50 g/cm 3 .…”

“…E. Park, K.E. Olson etc. (2006) points out that challenges of deepwater in well depths that can exceed 20,000 ft with pore pressures greater than 20,000 psi and one major issue facing deepwater fracturing is generating enough bottomhole treating pressure to create a hydraulic fracture at the sandface without exceeding the limitations of the hydraulic equipment at the surface.…”

“…(2006) points out that challenges of deepwater in well depths that can exceed 20,000 ft with pore pressures greater than 20,000 psi and one major issue facing deepwater fracturing is generating enough bottomhole treating pressure to create a hydraulic fracture at the sandface without exceeding the limitations of the hydraulic equipment at the surface. [3] D.V. Satya Gupta etc(2009) poits out that ultra-deep wells usually have pressured or over-pressured formations and require heavyweight brines to control hydrostatic pressures.…”