{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/54550"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/54550","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Depositional and Diagenetic History of the Permian Unayzah A Reservoir, South Haradh, Saudi Arabia with Implications for Deep Gas Exploration and Development","abstract":"The Early Permian Unayzah A member in the Ghawar area of east-central Saudi Arabia is a prolific gas producer but is characterized by significant reservoir heterogeneity related to complex interbedding, on the scale of 5 meters or less, of eolian dune, sand sheet, interdune and ephemeral (playa) lake facies. Diagenetic products in Unayzah A developed during a continuum of eogenetic and mesogenetic reactions. Early or eogenetic cements are dominated by clay rims that formed at temperatures below 70oC. Oil migration along stylolites probably from Silurian source rocks occurred during the early mesogenetic stage followed by barite, quartz and carbonate cementation. Oil degradation at temperatures between 150o and 225oC produced acidic pore fluids that caused dissolution of earlier formed carbonates to generate secondary intragranular, moldic and micro pores. Thin, early clay and hydrocarbon rims as well as possible early microquartz cements inhibited cementation of primary intergranular pores that are only partially filled with quartz outgrowth crystals. Total porosity, including primary open pores, secondary pores, and bitumen-coated and filled pores ranges up to 27 percent. Reservoir quality and heterogeneity are a function of depositional environment and diagenesis in which eolian dune and sand sheet facies contain the highest total porosities and hence the best reservoir properties. Some previously recognized Stoke's surfaces are characterized by higher concentrations of quartz cement further compromising reservoir interconnectivity.","abstract_html":"The Early Permian Unayzah A member in the Ghawar area of east-central Saudi Arabia is a prolific gas producer but is characterized by significant reservoir heterogeneity related to complex interbedding, on the scale of 5 meters or less, of eolian dune, sand sheet, interdune and ephemeral (playa) lake facies. Diagenetic products in Unayzah A developed during a continuum of eogenetic and mesogenetic reactions. Early or eogenetic cements are dominated by clay rims that formed at temperatures below 70oC. Oil migration along stylolites probably from Silurian source rocks occurred during the early mesogenetic stage followed by barite, quartz and carbonate cementation. Oil degradation at temperatures between 150o and 225oC produced acidic pore fluids that caused dissolution of earlier formed carbonates to generate secondary intragranular, moldic and micro pores. Thin, early clay and hydrocarbon rims as well as possible early microquartz cements inhibited cementation of primary intergranular pores that are only partially filled with quartz outgrowth crystals. Total porosity, including primary open pores, secondary pores, and bitumen-coated and filled pores ranges up to 27 percent. Reservoir quality and heterogeneity are a function of depositional environment and diagenesis in which eolian dune and sand sheet facies contain the highest total porosities and hence the best reservoir properties. Some previously recognized Stoke's surfaces are characterized by higher concentrations of quartz cement further compromising reservoir interconnectivity.","abstract_has_math":false,"creators":["Althani, Lulwah Faisal"],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Geosciences","degree_department":"Geosciences","school":null,"contributors":[],"advisors":[],"committee_chairs":["Eriksson, Kenneth A."],"committee_members":["Melvin, John","Romans, Brian W."],"year":2014,"date_issued":"2014-01-17","date_published":"2014-01-17","updated_at":"2026-07-22T22:18:52Z","subjects":["sandstone diagenesis","reservoir characteristics","Unayzah A"],"languages":[],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:2120"],"render_values":[{"text":"vt_gsexam:2120","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/54550","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Eriksson, Kenneth A."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Melvin, John","Romans, Brian W."]},{"key":"dc:contributor.department","label":"Department","values":["Geosciences"]},{"key":"dc:creator","label":"Author","values":["Althani, Lulwah Faisal"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2015-07-12T06:00:08Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2015-07-12T06:00:08Z"]},{"key":"dc:date.issued","label":"Date","values":["2014-01-17"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Geosciences"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["sandstone diagenesis","reservoir characteristics","Unayzah A"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:2120"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/54550"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The Early Permian Unayzah A member in the Ghawar area of east-central Saudi Arabia is a prolific gas producer but is characterized by significant reservoir heterogeneity related to complex interbedding, on the scale of 5 meters or less, of eolian dune, sand sheet, interdune and ephemeral (playa) lake facies. Diagenetic products in Unayzah A developed during a continuum of eogenetic and mesogenetic reactions. Early or eogenetic cements are dominated by clay rims that formed at temperatures below 70oC. Oil migration along stylolites probably from Silurian source rocks occurred during the early mesogenetic stage followed by barite, quartz and carbonate cementation. Oil degradation at temperatures between 150o and 225oC produced acidic pore fluids that caused dissolution of earlier formed carbonates to generate secondary intragranular, moldic and micro pores. Thin, early clay and hydrocarbon rims as well as possible early microquartz cements inhibited cementation of primary intergranular pores that are only partially filled with quartz outgrowth crystals. Total porosity, including primary open pores, secondary pores, and bitumen-coated and filled pores ranges up to 27 percent. Reservoir quality and heterogeneity are a function of depositional environment and diagenesis in which eolian dune and sand sheet facies contain the highest total porosities and hence the best reservoir properties. Some previously recognized Stoke's surfaces are characterized by higher concentrations of quartz cement further compromising reservoir interconnectivity."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["ETD"]},{"key":"dc:title","label":"Title","values":["Depositional and Diagenetic History of the Permian Unayzah A Reservoir, South Haradh, Saudi Arabia with Implications for Deep Gas Exploration and Development"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Eriksson, Kenneth A."],"dc:contributor.committeemember":["Melvin, John","Romans, Brian W."],"dc:contributor.department":["Geosciences"],"dc:creator":["Althani, Lulwah Faisal"],"dc:date.accessioned":["2015-07-12T06:00:08Z"],"dc:date.available":["2015-07-12T06:00:08Z"],"dc:date.issued":["2014-01-17"],"dc:description.abstract":["The Early Permian Unayzah A member in the Ghawar area of east-central Saudi Arabia is a prolific gas producer but is characterized by significant reservoir heterogeneity related to complex interbedding, on the scale of 5 meters or less, of eolian dune, sand sheet, interdune and ephemeral (playa) lake facies. Diagenetic products in Unayzah A developed during a continuum of eogenetic and mesogenetic reactions. Early or eogenetic cements are dominated by clay rims that formed at temperatures below 70oC. Oil migration along stylolites probably from Silurian source rocks occurred during the early mesogenetic stage followed by barite, quartz and carbonate cementation. Oil degradation at temperatures between 150o and 225oC produced acidic pore fluids that caused dissolution of earlier formed carbonates to generate secondary intragranular, moldic and micro pores. Thin, early clay and hydrocarbon rims as well as possible early microquartz cements inhibited cementation of primary intergranular pores that are only partially filled with quartz outgrowth crystals. Total porosity, including primary open pores, secondary pores, and bitumen-coated and filled pores ranges up to 27 percent. Reservoir quality and heterogeneity are a function of depositional environment and diagenesis in which eolian dune and sand sheet facies contain the highest total porosities and hence the best reservoir properties. Some previously recognized Stoke's surfaces are characterized by higher concentrations of quartz cement further compromising reservoir interconnectivity."],"dc:description.degree":["Master of Science"],"dc:format.medium":["ETD"],"dc:identifier.other":["vt_gsexam:2120"],"dc:identifier.uri":["http://hdl.handle.net/10919/54550"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["sandstone diagenesis","reservoir characteristics","Unayzah A"],"dc:title":["Depositional and Diagenetic History of the Permian Unayzah A Reservoir, South Haradh, Saudi Arabia with Implications for Deep Gas Exploration and Development"],"dc:type":["Thesis"],"thesis:degree_discipline":["Geosciences"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:18:52Z"}