Speaker: Lou Mazzullo
Topic: Development Strategies for the Morrow Formation
Synopsis: DEVELOPMENT STRATEGIES FOR THE MORROW FORMATION
Louis J. Mazzullo, Mazzullo Energy Corp., Denver, Colorado
Reservoir under-development of oil and gas resources of the lower Pennsylvanian Morrow Formation is a pervasive problem wherever the Morrow is productive, and it is related to several factors, both geological and logistical. On the logistical side, there are certain areas where the Morrow cannot be developed conventionally because of land use restrictions or resource development conflicts (e.g., Walsh, AAPG Bull. 91, pp. 1217-1229). On the geological side, there are depositional, tectonic, and diagenetic factors that make prediction of reservoir trends difficult in some places.
The Morrow records a cyclic sequence of clastics and associated, coeval carbonates in the Permian Basin of southeastern New Mexico, as it similarly does in the Denver Basin. As I will demonstrate for the Permian Basin, at least part of the Morrow Formation was affected by recurrent tectonic movement that continued after the initial late Mississippian event, which locally uplifted and eroded earlier Morrow sediments, and in other places provided accommodation space for Morrow sedimentation. Deposition of later Morrow sediments occurred above this intraformational unconformity, creating an unusual reservoir mosaic in places. Reservoirs below this unconformity may be discontinuous or exhibit geometries that do not fit the exploration or development model being used. Glacioeustatic-imposed facies changes throughout the Morrow section at any given location also make it difficult to employ a specific exploration or development approach, as reservoir geometries can change from one horizon to the next, below or above the intraformational unconformity. Diagenetic occlusion resulting from channel abandonment or clay mineralization further modifies reservoir shapes extents, and can create localized permeability barriers that can effectively compartmentalize reservoirs, even within a specific reservoir zone. These types of effects can occur either naturally or by drilling-induced formation damage. As a result of all of these factors, reservoirs are either missed in offset wells, or inadequately drained.
Vertical wells are essential to Morrow development because often, there can be several discrete pay horizons in a given wellbore, which helps reduce risk. However, once a productive area is delineated with vertical wells, resource extraction becomes inefficient because of the number of geologic factors that can effect individual pay zones. In areas where well control is dense enough, particularly in older fields that are developed in areas where the Morrow is not very thick, it may be possible to enhance production through the use of detailed reservoir modeling and horizontal drilling. Since the better reservoirs tend to be developed in more carbonaceous-rich fluvial and transitional marine environments in the Morrow, the shales themselves may serve as both source and seal for the associated sand bodies, and can add to the resource budget in a new well. However, the geologic factors that affected those sand bodies must be thoroughly understood and reservoir geometries accurately determined before laterals can be planned. Mapping of discrete reservoir units can be done with a variety of subsurface techniques, as well as, in some cases, the use of 3D seismic. Examples from the Permian and Denver Basins will be given to illustrate these concepts.
BIOGRAPHICAL SKETCH
LOUIS J. MAZZULLO
President, Mazzullo Energy Corp., Denver, CO
Geological Consulting Services, all western U. S. Basins
Previously Senior Exploration Geologist, Brigham Oil & Gas, Austin; Geological Manager, Nearburg Producing Co., Midland
Been an independent consultant for the better part of the last 30 years
Brooklyn, NY native
B.S. Cum Laude w/honors in Geology, Brooklyn College CUNY
Masters degrees from SUNY Stony Brook (Earth & Space Sciences) and University of Chicago (Geophysical Sciences)
PBS-SEPM 1988-89, President
Rocky Mountain Section AAPG- President, 1999-2000
WTGS Member 1981- present
Dedicated Service Award, 1992-93
AAPG Member 1977- present, Certified Petroleum Geologist
Wyoming Registered Geologist #PG-974
Levorsen Award Recipient, 1990 & 1999, Southwest Section AAPG
Cheney Science Award, 2005- Southwest Section AAPG