Current Status of the Multiwell Experiment

Northrop, D.A.; Sattler, A.R.; Mann, R.L.; Frohne, K.H.

doi:10.2523/12868-ms

Cited by 8 publications

(3 citation statements)

References 2 publications

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“…The MWX consists of three closely spaced wells on a site in the Piceance basin of western Colorado near Rifle. 1 The stratigraphic unit targeted for research in the MWX is the Cretaceous Mesaverde group. The Mesaverde consists of nearly 5,000 ft [1525 m] of clastic sedimentary rocks at the MWX site and is divided into three formations.…”

Section: Introductionmentioning

confidence: 99%

“…The tight sandstone units in the MWX were characterized by several different methods, including wireline logging, seismic surveys, interference testing, and a comprehensive core analysis program. 1 criteria: cores were chosen from sandstone intervals determined by well logs to be gas-bearing, and the samples selected were from the portion of each gas-bearing interval that exhibited the lowest gamma ray response. These criteria were applied to ensure that the rocks investigated would consist of samples from zones in the MWX wells that had the greatest potential for gas production.…”

Section: Introductionmentioning

confidence: 99%

“…6 All 44 MWX plug samples were run in the CORAL after being dried in the relative-humidity oven to baseline water saturation. Parameters measured on these dry cores consisted of (1) porosity to gas at initial reservoir net confining stress, (2) PV compressibility measured for a I,OOO-psi (6.89-MPa) step that ended with the cores at net confining stress equivalent to the midpoint of reservoir drawdown, (3) permeability as a function of pore pressure at constant net stress for the calculation of the Klinkenberg 7 parameters k 00 and B from the equation k=koo(1 +Blp), and (4) the confiningstress. dependence of permeability at constant pore pressure.…”

Section: Introductionmentioning

confidence: 99%

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Porosity, Permeability, and Pore Structure of the Tight Mesaverde Sandstone, Piceance Basin, Colorado

Soeder

Randolph

1987

SPE Formation Evaluation

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Special core analyses on 44 tight Mesaverde sandstone samples from the U.S. DOE Multiwell Experiment (MWX) were combined with petrographic investigations to relate the porosity and permeability of the cores to the pore structure of the rocks. Core analysis was performed on I-in. [2.54-cm] -diameter horizontal plug samples with a computerized steady-state-flow measuring device that routinely measures gas flow rates with a resolution of better than 10 -6 std cm 3 /s. All samples were selected from intervals expected to be gas-productive on the basis of wireline well logs and were taken from the portion of the interval that showed the lowest gamma ray log response. The core plugs were measured for dry permeability to gas, relative permeability at various water saturations, porosity to gas, and PV compressibility. Petrographic samples were taken directly off the plug ends and were analyzed with both an optical microscope and a scanning electron microscope (SEM). The petrographic study was explicitly directed toward observing the flow paths and pore structure deduced from the core analysis data.Petrographic observations revealed that the pore geometry of tight sandstone falls into three general categories: grain-supported primary pores, secondary solution pores connected by narrow intergranular slots (the most common pore structure in the Mesaverde), and matrix-supported grains. Reservoir properties measured from core analysis correlated fairly well with the observed pore geometry and showed trends associated with various depositional environments in the formation.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Porosity, Permeability, and Pore Structure of the Tight Mesaverde Sandstone, Piceance Basin, Colorado

Soeder

Randolph

1987

SPE Formation Evaluation

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Pressure Core Measurements in Tight Sandstone Lenses During the Multiwell Experiment

Sattler

Heckes

Clark

1988

SPE Formation Evaluation

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A pressure coring operation was performed in two tight sandstone lenses of the Mesaverde group during the drilling of one well of DOE's Multi-Well Experiment. The goals were:to obtain accurate water saturation data;to measure the amount and composition of gas on a foot-by-foot basis; andto recover fluids for water chemistry analysis. This application of pressure coring bad not been tried before; it was felt to be the best approach for accurate water saturation measurements in tight sandstone core. Several changes to usual pressure coring procedures were adopted. These included the procedures were adopted. These included the development of an organic noninvasive coring fluid, compatible with the oil-based drilling fluid used, that would help preserve water saturation. Three 15-ft pressure cove barrels were taken in two sandstone lenses 20 and 30 ft thick; all three barrels were filled with sandstone. Goals 1 and 2 were met. Water saturation values are reported and discussed. The type and duration of the water extraction processes ave shown to be very important in determining water saturations in tight sands. Gas species and amount are available on a foot-by-foot basis. Introduction The Multi-Well Experiment (MWX) is a research-oriented field laboratory and it is the major production technology activity of the Department of Energy sponsored Western Gas Sands Project. The overall MWX objectives are to Project. The overall MWX objectives are to thoroughly characterize lenticular gas sand reservoirs and evaluate technology for their production. A major activity of the Multi-Well production. A major activity of the Multi-Well Experiment is the core program. This paper deals with one major aspect of the M" core program, the design and execution of a pressure core operation in tight sands with accompanying pressure core analysis. The effect of water saturation is extremely important in tight sands; permeability is very strongly dependent upon water saturation. For example, water saturations of 15%, 30%, 40% and 50% reduced the permeabilities of a Multi-Well Experiment core sample by factors of 0.61, 0.33, 0.25 and 0.05 respectively. Thus, an unambiguous technique to accurately measure water saturation becomes extremely important. There is general concern with the accuracy of water saturations measured in core because fluids may be excluded when core is brought to the surface. Additionally, drilling fluids may penetrate into the cove, especially if water-based penetrate into the cove, especially if water-based fluids are used. It was believed that pressure coring would circumvent the first problem and the core could be brought to the surface intact with all its fluids. The use of organically based drilling fluids, with suitable tagging, would alleviate the second problem. Therefore, a pressure coring operation was undertaken in the tight sandstone of the Mesaverde group in the second well, MWX-2, of the Multi-Well Experiment. At the time it was undertaken it was felt to be the best approach for water saturation measurements in tight sandstone core. This application of pressure coring had not been tried before. Specifically, the goals of the project were to:obtain accurate water saturation data.obtain both the amount and species of gas foreach foot of pressure core taken.Obtain fluids from the thawing of the pressurecore for water chemistry analysis. P. 229

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The Multiwell Experiment Core Program, II

Sattler

1984

All Days

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An unprecedented core analysis program is under way as part of DOE's Multi-Well Experiment (MWX). MWX is a research-oriented field laboratory whose objectives are to thoroughly characterize lenticular tight gas sands and to develop technology for their production. Over 4100 ft (1250 m) of core were taken from three wells separated by only about 115-215 ft (35-66 m) at depth. All major categories of core analysis are reviewed and results through December 1983 are included. Those include routine core analysis, restored state reservoir parameter measurements, electrical measurements, mechanical rock property data, mineralogy, organic maturation, natural fractures, and geochemistry. This paper also describes the laboratory work on core and formation invasion and the development of instruments that were used in the field processing of the core.

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Current Status of the Multiwell Experiment

Cited by 8 publications

References 2 publications

Porosity, Permeability, and Pore Structure of the Tight Mesaverde Sandstone, Piceance Basin, Colorado

Porosity, Permeability, and Pore Structure of the Tight Mesaverde Sandstone, Piceance Basin, Colorado

Pressure Core Measurements in Tight Sandstone Lenses During the Multiwell Experiment

The Multiwell Experiment Core Program, II

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