New Drilling-Fluid Solution for Unconventional Sand Wells in the San Juan Area

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractDuring the last several years, drilling deviated wells through highly bentonitic shallow formations and unconventional coal bed gas sands in the San Juan area of the Rocky Mountains has indicated the need for fluids as inhibitive as a 7% KCl/polymer system. Operators have experienced advantages with this type of system in terms of wellbore stability, penetration rates, wellbore workability and well productivity. However, increasing environmental restraints in the area make the economics of this system less desirable in terms of hauloff and disposal costs. Core samples of reactive shales in the area were analyzed to determine if a freshwater-based system could be formulated to achieve similar performance to what was previously achieved with the 7% KCl system. Several different freshwater-based muds were tested in the lab, including some high performance water-based fluids. This paper describes criteria that enables a fluid to be called a high performance fluid and reviews the data that yielded a "fit-forpurpose" high performance fluid designed for the specific clay mineralogy of the San Juan area. A field trial was initiated to decide if the lab results could be verified by actual drilling data. Performance data from the trial wells are reviewed and compared directly against the previous successful system. The paper illustrates how a fit-for-purpose high performance water-base mud can help the economics of unconventional gas sand drilling.

Drilling for Coalbed Methane in the San Juan Basin With Coiled Tubing: Results, Learnings, and a World First

“…However, the hybrid concept is not new, as rigs of similar construction have successfully drilled and completed over 450 wells on Alaska's North Slope as well as many vertical wells in Canada. 9,14,15 The layout was similar to most land drilling rigs ( Fig. 2) and all of the main rig components were trailer mounted.…”