RIASSUNTO
Abstract
A high inclination directional drill hole was designed as a conduit to carry a fresh water pipeline from an intermediate pump station to the south rim of the Grand Canyon. This use of directional drilling technology was judged superior to an external pipeline for reasons of worker safety, aesthetics, pipeline protection and costs. The hole was designed to meet Park Service criteria: sufficient diameter to contain 8"" water line and exit point accessibility.
The hole was drilled to a maximum inclination of 70 deg. True vertical depth was 2800 ft (855 m) and horizontal displacement was 3800 ft (1160 m). Measured depth along the wellbore was 5075 ft. (1555 m).
A ""build-and-hold"" pattern was employed from below surface casing, using positive displacement motors, tricone bits and ""build"" type rotary drilling assemblies. An air and mist circulating system was employed. Modifications of mud drilling equipment were made for air service.
Primary directional measurement was performed with magnetic singleshot instruments. Three confirmation/comparison gyro runs were made. The visibility and accessibility of the exit point afforded an opportunity to compare downhole surveying techniques with surface systems of known and verifiable accuracy.
Drilling problems encountered included: loss of circulation, fractures, solution cavities, severe torque and drag, severe drill string damage, hole cleaning, and sealing and cementing of an open-ended annulus. Solutions considered and implemented are discussed.
Introduction
There is no major water source on the South Rim of the Grand Canyon National Park, site of the majority of tourist facilities. In 1983 the National Park Service determined the existing water supply and distribution system to be inadequate to serve the Park's approximately 2-3 million yearly visitors. The yearly demand was approaching the maximum supply, and peak supply rate, causing for improvements of the existing system, which had grown in stages as the Park's popularity had grown.
In the 1930's an unreliable spring of approximately 300 gpm (1100 1pm) was tapped at Indian Gardens (Point D of Figure 1.). An external pipeline was built to permit pumping of water from Indian Gardens directly into the distribution system on the rim. ( This line is not indicated on the Figure.)
In the 1960's the water of Roaring Springs was tapped and delivered by means of the Transcanyon Pipeline (F and E respectively on Figure 1) to Indian Gardens, a distance of approximately 15 miles (24 Km) at a maximum rate of 700 gpm 2650 1pm). The water was then pumped through the external pipeline to the rim.
The overall improvement of the water system called for installation of additional pumping capacity at Indian Gardens, an additional pipeline from Indian Gardens to the South Rim, and a continuation of that pipeline to the surface storage facilities. It was a conduit for the Indian Gardens to the South Rim pipeline that the drill hole was designed.
P. 1047^