Academic Affiliation: University of Puerto Rico at Mayagüez
Luis G. Montalvo Lliteras is a native of Puerto Rico and grew up in the southwest coast of the island in a town called Cabo Rojo. His academic interests are in carbonate sedimentology, diagenesis, dolomitization and the effects of sea level changes throughout geologic time. During the summer of 2011, Luis participated in a joint internship between RESESS and Shell Western Exploration and Production (SWEPI LP), working in Houston, TX. This was an exciting new experience for him in which he worked with many geologists and engineers on analyzing the distribution of hazardous drilling events in shales using mud logs and drilling reports for an area in northwestern Louisiana. Luis loves hiking, camping, and snorkeling. He creates music beats and complete tracks using various music software programs, and sometimes works as a d.j. in night clubs.
2010- Diagenetic history of the Ellenburger Group in the Fort Worth Basin, Texas
The Ellenburger group on the subsurface of the Fort Worth Basin, Texas, has undergone several episodes of diagenesis during karstification and burial, which resulted in various phases of dolomitization. Identifying the evolution pattern of the diagenetic processes is required for upcoming studies regarding hydrocarbon exploration and natural gas productivity in the Fort Worth Basin. Core samples used in this study were divided into five different lithologies: dolostone, dolostone breccia, dolomitic mudstone, dolomitic ooid grainstone, and dolomitic wackestone-packstone. Five types of dolomites were also identified using petrography (polarizing microscopy, reflected light microscopy and cathodoluminesence). Dolomite type 1 is characterized by the very fine crystalline dolomite and the preservation of primary sedimentary structures. It was interpreted as forming shortly after deposition of lime mud. After deposition, karstification developed vugs, cavities, and collapse breccias. Freshwater resulted in extensive calcification followed by silicification. Shallow burial of the Ellenburger developed fractures, dissolution seams, and stylolites that were later filled or replaced by dolomite types 2 and 3. Dolomite type 2 is found associated with dissolution seams. Dolomite type 3 is found in fractures and stylolites within the calcites. Type 4 dolomite replaces earlier dolomites and is usually found in dolostones. Type 4 was interpreted as a deep burial dolomite. Dolomite type 5 is a cementing dolomite found in veins and vugs. It is characterized by saddle dolomite that formed at slightly elevated temperatures. A paragenetic sequence (figure 1) that summarizes the events recorded in the core samples was constructed based on the petrographic observations. The resulting paragenesis is consistent with what has been reported from the Permian Basin.
2011- Evaluation of drilling events in the Haynesville and Bossier Shale, Magnolia, NW Louisiana
The Magnolia field in NW Louisiana has been a potential target for the drilling of gas wells by Shell Exploration and Production and Encana since 2007. Data taken from drilling reports and mudlogs was used to create geohazard maps for the Haynesville and Bossier shales in the Magnolia AMI (area of mutual interest). Three types of drilling events were identified: gas shows (circles in figure), circulation loss (crosses in figure) and failed Formation Integrity Test (LOT) (crosses in figure). An evaluation was done using reports and mudlogs to explain the genesis of each of these events in two categories: lithology related or fracture related events (includes faults). Using the software, Schlumberger Petrel 2009.2, well sections were used to plot the stratigraphic location of these events, and geohazard maps were generated to analyze their aerial distributions. Correlation of events was possible in some areas and three hazard zones were found in the Lower Bossier stratigraphic layer. The Lower Bossier is the stratigraphic interval with the largest amount of gas shows due to a slight change in permeability making it easier to expel gas while drilling. This is consistent with the estimated amount of generated gas found on the Lower Bossier by other studies. The Upper Bossier is the depth at which the larger amount of circulation losses was detected. Fewer events where found at the Haynesville, which is the present target for gas production. Geohazard maps were developed and compared with data for Estimated Ultimate Recoveries (EUR) to correlate drilling events with the production of Shell and Encana wells. No correlation is found because gas shows are happening on nonproducing intervals and the amount of gas shows can be affected by drilling parameters.
Diagenetic history of the Ellenburger Group in the Fort Worth Basin, Texas
Evaluation of drilling events in the Haynesville and Bossier Shale, Magnolia, NW Louisiana