Petroleum explorationists have commonly assumed, based on the presence of volcanic and/or volcaniclastic rock, that regions such as northcentral Oregon do not hold potential as petroleum basins. The typical argument has been that volcanic flows have no effective porosity or permeability and poorly sorted volcaniclastic sediments contain a high percentage of mineralogically unstable grains which are too easily and rapidly altered into clays and zeolites for any significant or effective porosity to be retained.
The objective of this study was to determine if potential petroleum reservoir rocks do exist in north-central Oregon. Through field and laboratory study and by comparing this region with petroleum producing basins with volcanic and volcaniclastic reservoirs, I have determined that the potential volcanic and volcaniclastic reservoirs of this area cannot be entirely \"judged\" by the \"rules\" of average siliciclastic reservoirs. Secondary dissolution and fracture porosity is extremely important in these reservoirs and is the natural consequence of hydration reactions, the formation of organic acids during thermal maturation of associated organic rich source rocks, high geothermal gradients which increase the rate of dissolution of some grains, the flushing of dissolution products out of the reservoirs during diagenesis, and the development of fracture porosity in a tectonically active area. As a result of this study, I have concluded that north-central Oregon does in fact have good potential petroleum reservoir rocks.
","abstract_html":"<p>Petroleum explorationists have commonly assumed, based on the presence of volcanic and/or volcaniclastic rock, that regions such as northcentral Oregon do not hold potential as petroleum basins. The typical argument has been that volcanic flows have no effective porosity or permeability and poorly sorted volcaniclastic sediments contain a high percentage of mineralogically unstable grains which are too easily and rapidly altered into clays and zeolites for any significant or effective porosity to be retained.</p> <p>The objective of this study was to determine if potential petroleum reservoir rocks do exist in north-central Oregon. Through field and laboratory study and by comparing this region with petroleum producing basins with volcanic and volcaniclastic reservoirs, I have determined that the potential volcanic and volcaniclastic reservoirs of this area cannot be entirely "judged" by the "rules" of average siliciclastic reservoirs. Secondary dissolution and fracture porosity is extremely important in these reservoirs and is the natural consequence of hydration reactions, the formation of organic acids during thermal maturation of associated organic rich source rocks, high geothermal gradients which increase the rate of dissolution of some grains, the flushing of dissolution products out of the reservoirs during diagenesis, and the development of fracture porosity in a tectonically active area. As a result of this study, I have concluded that north-central Oregon does in fact have good potential petroleum reservoir rocks.</p>","abstract_has_math":false,"creators":["Riddle, Alfred J."],"institution":null,"degree_name":"Master of Science (MS)","degree_level":"Thesis","degree_discipline":"Geology","degree_department":null,"school":null,"contributors":["Lanny H. Fisk","H. Paul Buchheim","Ivan G. Holmes"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1990,"date_issued":"1990-08-01T07:00:00Z","date_published":"1990-08-01T07:00:00Z","updated_at":"2026-07-24T02:53:20Z","subjects":["Geology","Petroleum -- Geology -- Oregon; Petroleum -- Reserves -- Oregon; Rocks, Igneous"],"languages":["English"],"rights":["This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights."],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://scholarsrepository.llu.edu/etd/767","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Lanny H. Fisk","H. Paul Buchheim","Ivan G. Holmes"]},{"key":"dc:creator","label":"Author","values":["Riddle, Alfred J."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"thesis:degree_discipline","label":"Discipline","values":["Geology"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science (MS)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Geology","Petroleum -- Geology -- Oregon; Petroleum -- Reserves -- Oregon; Rocks, Igneous"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["English"]},{"key":"dc:rights","label":"Dc Rights","values":["This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://scholarsrepository.llu.edu/etd/767"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Petroleum explorationists have commonly assumed, based on the presence of volcanic and/or volcaniclastic rock, that regions such as northcentral Oregon do not hold potential as petroleum basins. The typical argument has been that volcanic flows have no effective porosity or permeability and poorly sorted volcaniclastic sediments contain a high percentage of mineralogically unstable grains which are too easily and rapidly altered into clays and zeolites for any significant or effective porosity to be retained.
The objective of this study was to determine if potential petroleum reservoir rocks do exist in north-central Oregon. Through field and laboratory study and by comparing this region with petroleum producing basins with volcanic and volcaniclastic reservoirs, I have determined that the potential volcanic and volcaniclastic reservoirs of this area cannot be entirely \"judged\" by the \"rules\" of average siliciclastic reservoirs. Secondary dissolution and fracture porosity is extremely important in these reservoirs and is the natural consequence of hydration reactions, the formation of organic acids during thermal maturation of associated organic rich source rocks, high geothermal gradients which increase the rate of dissolution of some grains, the flushing of dissolution products out of the reservoirs during diagenesis, and the development of fracture porosity in a tectonically active area. As a result of this study, I have concluded that north-central Oregon does in fact have good potential petroleum reservoir rocks.
"]},{"key":"dc:title","label":"Title","values":["Potential Petroleum Reservoir Rocks of North-Central Oregon"]}]}],"canonical_facts":{"dc:contributor":["Lanny H. Fisk","H. Paul Buchheim","Ivan G. Holmes"],"dc:creator":["Riddle, Alfred J."],"dc:description.abstract":["Petroleum explorationists have commonly assumed, based on the presence of volcanic and/or volcaniclastic rock, that regions such as northcentral Oregon do not hold potential as petroleum basins. The typical argument has been that volcanic flows have no effective porosity or permeability and poorly sorted volcaniclastic sediments contain a high percentage of mineralogically unstable grains which are too easily and rapidly altered into clays and zeolites for any significant or effective porosity to be retained.
The objective of this study was to determine if potential petroleum reservoir rocks do exist in north-central Oregon. Through field and laboratory study and by comparing this region with petroleum producing basins with volcanic and volcaniclastic reservoirs, I have determined that the potential volcanic and volcaniclastic reservoirs of this area cannot be entirely \"judged\" by the \"rules\" of average siliciclastic reservoirs. Secondary dissolution and fracture porosity is extremely important in these reservoirs and is the natural consequence of hydration reactions, the formation of organic acids during thermal maturation of associated organic rich source rocks, high geothermal gradients which increase the rate of dissolution of some grains, the flushing of dissolution products out of the reservoirs during diagenesis, and the development of fracture porosity in a tectonically active area. As a result of this study, I have concluded that north-central Oregon does in fact have good potential petroleum reservoir rocks.
"],"dc:identifier":["https://scholarsrepository.llu.edu/etd/767"],"dc:language":["English"],"dc:rights":["This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights."],"dc:subject":["Geology","Petroleum -- Geology -- Oregon; Petroleum -- Reserves -- Oregon; Rocks, Igneous"],"dc:title":["Potential Petroleum Reservoir Rocks of North-Central Oregon"],"thesis:degree_discipline":["Geology"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["Master of Science (MS)"]},"updated_at":"2026-07-24T02:53:20Z"}