Report of Investigations No. 131 Origin and Diagenesis of Cap Rock, Gyp Hill and Oakwood Salt Domes, Texas

UT Librarie

Steerable filters generated with the hypercomplex dual-tree wavelet transform

The use of wavelets in the image processing domain is still in its infancy, and largely associated with image compression. With the advent of the dual-tree hypercomplex wavelet transform (DHWT) and its improved shift invariance and directional selectivity, applications in other areas of image processing are more conceivable. This paper discusses the problems and solutions in developing the DHWT and its inverse. It also offers a practical implementation of the algorithms involved. The aim of this work is to apply the DHWT in machine vision. Tentative work on a possible new way of feature extraction is presented. The paper shows that 2-D hypercomplex basis wavelets can be used to generate steerable filters which allow rotation as well as translation.</p

Report of Investigations No. 123 Petroleum Potential of the Palo Duro Basin, Texas Panhandle

UT Librarie

A machine vision extension for the Ruby programming language

Dynamically typed scripting languages have become popular in recent years. Although interpreted languages allow for substantial reduction of software development time, they are often rejected due to performance concerns. In this paper we present an extension for the programming language Ruby, called HornetsEye, which facilitates the development of real-time machine vision algorithms within Ruby. Apart from providing integration of crucial libraries for input and output, HornetsEye provides fast native implementations (compiled code) for a generic set of array operators. Different array operators were compared with equivalent implementations in C++. Not only was it possible to achieve comparable real-time performance, but also to exceed the efficiency of the C++ implementation in several cases. Implementations of several algorithms were given to demonstrate how the array operators can be used to create concise implementations.</p

State Lands Energy Resource Optimization Project

Project SLERO, for which The University of Texas at Austin Bureau of Economic Geology was the lead contractor and coordinating institution, was a five-university consortium study of hydrocarbon resources on Texas State Lands. The five universities are The University of Texas at Austin, Texas A&M University, the University of Houston, Texas Tech University, and Lamar University, and the entire program was aided by the cooperation of the Texas General Land Office. This 4-year project was funded through the Office of the Governor of Texas. Project personnel included geologists, petroleum engineers, geophysicists, and chemists. The interdisciplinary nature of this project was directed toward a more thorough understanding of the geologic controls on production and the development of appropriate recovery technologies to address the specific needs of State Lands reservoirs. Transfer of these technologies to industry, in particular to independent operators, is expected to result in increased efficiency of hydrocarbon recovery from State Lands and increased revenue to the Texas Public School Fund. The project was divided into three parts: (1) play analysis and resource assessment, (2) reservoir characterization, and (3) development of advanced extraction technology.Bureau of Economic Geolog

Diagenesis and Burial History of the Lower Cretaceous Travis Peak Formation, East Texas: Controls on Permeability in a Tight Gas Sandstone

Petrographic and geochemical studies were used to determine the diagenetic and burial history of Travis Peak sandstones in East Texas and to relate the diagenesis to permeability variations within the formation. Permeability in much of the formation has been reduced to less than 0.1 md by compaction, cementation, and minor pressure solution. Travis Peak sandstone is quartzarenite and subarkose, having an average composition of Q95F4R1. The first authigenic cements to precipitate were illite, which coated detrital grains with tangentially oriented crystals, and dolomite. Next, extensive quartz cement, averaging 17% of the rock volume in well-sorted sandstone, occluded much of the primary porosity. Quartz is most abundant in the lower Travis Peak, in well-connected sandstone beds that were deposited in braided streams. Dissolution of orthoclase and albitization of plagioclase followed quartz cementation and occurred prior to mid-Cretaceous movement of the Sabine Uplift. Illite, chlorite, and ankerite precipitated after feldspar diagenesis. Oil migrated into Travis Peak reservoirs in the Late Cretaceous from Jurassic source rocks. Later deasphalting of the oil filled much of the remaining porosity in some zones near the top of the formation with reservoir bitumen.Bureau of Economic Geolog

Travis Peak Formation, East Texas

Sandstone in the Travis Peak (Hosston) Formation has been extensively modified by burial diagenesis. Permeability in much of the formation has been reduced to less than 0.1 md as a result of compaction extensive precipitation of authigenic minerals, and minor pressure solution. Thin zones of higher porosity and permeability occur mainly near the top of the formation: porosity and permeability decrease with depth below the top. The Travis Peak Formation in East Texas is approximately 2,000 ft (600 m) thick; depth to the top of the formation ranges from 5,800 ft (1,770 m) to 9,400 ft (2,870 m). Travis Peak sandstone is fine- to very fine-grained quartzarenite and subarkose having an average composition of Q₉₅F₄R₁. Plagioclase feldspar is more abundant than orthoclase, and chert and low-rank metamorphic rock fragments are the most common lithic components. The first authigenic cement to precipitate was illite, which coated detrital grains with tangentially oriented crystals. Next, extensive quartz cement, averaging 17% of the rock volume in well-sorted sandstone, occluded much of the primary porosity. Quartz cement is most abundant in the lower Travis Peak, in well-connected sandstone beds that were deposited in braided streams. Oxygen-isotopic composition of quartz overgrowths indicates that they precipitated from meteoric fluids at temperatures of 130° to 165°F (55° to 75°C). These temperatures equate to depths of 3,000 to 5,000 ft (900 to 1,500 m). Dissolution of orthoclase and albitization of plagioclase followed quartz cementation and occurred prior to mid-Cretaceous movement of the Sabine Uplift. An abrupt loss of orthoclase occurs at 1,200 ft (365 m) below the top of the Travis Peak, and albitization is more extensive deeper in the formation. Illite (a second generation), chlorite, and ankerite precipitated after feldspar diagenesis; these late authigenic phases incorporate ferrous iron released by thermal reduction of iron compounds. Ankerite was derived primarily from early dolomite cement, but it incorporated some light carbon from maturation of organic matter and radiogenic strontium from feldspar dissolution. The oxygen-isotopic composition of pore fluids evolved during ankerite precipitation from -4 o/oo to +3 o/oo (SMOW); +3 o/oo is the present composition of Travis Peak water. Oil migrated into Travis Peak reservoirs about 65 mya from shale in the Bossier Formation. Later deasphalting of the oil filled much of the remaining porosity in some zones near the top of the formation with reservoir bitumen.Geological Science

Diagenetic Controls on Reservoir Properties of Low-Permeablity Sandstone, Frontier Formation, Moxa Arch, Southwest Wyoming

The Upper Cretaceous Frontier Formation, a low-permeability gas reservoir along the Moxa Arch in southwest Wyoming, comprises marine and nonmarine facies deposited in a fluvial-deltaic depositional system. The Second Frontier interval is present along the entire Moxa Arch and contains the most prolific Frontier gas reservoirs. Clean sandstone in the Second Frontier commonly occurs in marine upper-shoreface facies and fluvial channel-fill facies. According to petrographic examination of 199 thin sections, Frontier sandstones are fine- to medium-grained litharenites and sublitharenites having an average composition of 64 percent quartz, 6 percent feldspar, and 30 percent rock fragments. Clean sandstones contain an average of 1.6 percent primary intergranular porosity and 4.4 percent secondary porosity, which formed by dissolution of feldspar, chert, and mudstone clasts. Microporosity, estimated as the difference between porosimeter and thin-section porosity, averages 6 percent. Calcite, quartz, mixed-layer illite-smectite, and illite are the most abundant cements. Authigenic mixed-layer clays consist of about 80 percent illite layers, suggesting that clays may be only moderately sensitive to fresh water. On the basis of petrographic evidence, the relative order of occurrence of the major events in the diagenetic history of Frontier sandstones were (1) mechanical compaction by grain rearrangement and deformation of ductile grains, (2) formation of illite and mixed-layer illite-smectite rims, (3) precipitation of quartz overgrowths, (4) precipitation of calcite cement, (5) generation of secondary porosity by dissolution of calcite cement and detrital feldspar, chert, and mudstone, and (6) chemical compaction by intergranular pressure solution and stylolitization. Low permeability in Frontier sandstones is caused by (1) loss of porosity due to compaction, (2) occlusion of pores by cements, particularly calcite and quartz, and (3) lining of primary pores by fibrous illite. Unstressed permeability to air averages 0.21 md in 56 upper-shoreface sandstones (porosity = 15 percent), 0.14 md in 121 fluvial channel-fill sandstones (porosity = 10 percent), and 0.08 md in 279 lower-shoreface sandstones (porosity = 12 percent).Bureau of Economic Geolog