Fracturing and Testing Case Study of Paludal, Tight, Lenticular Gas Sands

Abstract

This paper is a case study of the stimulation and testing of tight, lenticular sands in the paludal interval of the Mesaverde group in the Piceance basin at DOE's Multiwell Experiment (MWX) site in Colorado. Topics discussed include geologic data, stress test results, well testing, laboratory core studies, stimulation and stimulation analyses, and postfracture operations.

Altered-Stress Fracturing

“…19 5. Some mechanism is needed to obtain high treatment pressures in the offset wells; High pressures may be attained as a result of reservoir features, such as good stress contrasts, or induced features, such as a screenout in the offset-well fracture.…”

Aplikasi Kurva Derivative Dalam Penentuan Batas Reservoir Pada Sistem Reservoir Lensa

“…Reservoir dengan tipe lensa telah banyak ditemukan dan populer terutama di Amerika Serikat. Berbagai penelitian (Warpinski, et al, 1985;Lorenz, 1985;Boardman & Knutson, 1981;Evans & Carroll, 1981;Craig & Brown, 1999;Zubari & Abdulwahab, 1999) telah dilakukan untuk dapat mengenali lebih dalam sifat dan karakter dari reservoir tersebut.…”

The Multiwell Experiment - A Field Laboratory in Tight Gas Sandstone Reservoirs

“…92 The high pressures may be caused by high stresses in the confining lithologies, backstresses, multiple fracturing, or the presence of thin, high-stress stringers in the reservoir. Single well test 'Generally after 10 days of production.…”

“…After 20 months of shut-in beneath a bridge plug while other operations were conducted uphole, this paludal zone was reentered and tested; it averaged 320 Mcf/D [9100 std m 3 /d] over 7 weeks. 92,97 No liquids were produced initially, but after 5 days of flowing, water production began and increased rapidly to about 35 BID [5.6 m 3 / d]. Re-entry results of the paludal zone show that the damage after the fracture was reversible and was probably caused by water and gel blockage of the natural fractures.…”

“…The five complete stimulation experiments executed in the fully characterized MWX reservoirs provided much information on fracturing performance in the lenticular Mesaverde sandstones. [20][21][22]92,104,105 Stimulation effectiveness was evaluated with a combination of state-of-the-art fracture design and execution under controlled conditions, fracture diagnostic instrumentation, core-based laboratory studies of the interaction of fracture fluids and proppants with the formation, and pre-and postfracture production performance testing'. This systems approach to analyzing the experiments demonstrated that fracture fluid compatibility with the stimulated formation, and the possible effects of formation damage, plays a large part in the performance of hydraulic fracturing in tight naturally fractured sandstones.…”