Industry and academia are teaming up to pump up productivity in the Mississippian of the Midcontinent United States.
The three-year project, launched in November, weaves together the expertise of 11 domestic and international oil and gas companies and the Oklahoma State University Boone Pickens School of Geology.
Despite substantial production over the last four decades from more than 14,000 vertical wells, Mississipian resource plays are the least understood of any in North America, said AAPG member Michael Grammer, OSU professor and project director.
The interdisciplinary project’s purpose is to describe the lower Mississippian carbonates based on depositional environment/geometry and modern sequence stratigraphy, and define the diagenetic overprint in order to understand and predict more accurately reservoir characteristics, controls and distribution, Grammer said.
Grammer said low-porosity limestones – so-called unconventional reservoirs – “may be significant producers in this interval and ... a detailed understanding of the geology will enhance horizontal drilling applications in this unit.”
He estimates hydrocarbons in the interval at five billion to six billion barrels of oil equivalent in place, calling it a “huge domestic resource ... virtually in our own backyard.”
The Mississippian covers much of northern Oklahoma and southern Kansas and is part of the Silurian-Devonian-Mississippian petroleum system consisting of rich source rocks (Woodford Shale) encased in limestones and dolomites, he said.
It is a thick carbonate sequence of complex reservoirs consisting of fractured limestones, tripolitic cherts and porous dolomites. In addition to multiple reservoir types, there are multiple fluid levels that effect productivity in these oil prone reservoirs, he said.
The OSU team includes five faculty members and 11 graduate students. Their general areas of responsibility are:
Companies initially involved include Chesapeake Energy, Devon Energy, Marathon Oil, Newfield Exploration, SandRidge Energy, Longfellow Energy, Red Fork Energy, Tip Top Energy (Sinopec), Chaparral Energy, Unit Corporation and SM Energy.
“Technical work will be performed primarily by OSU with input from consortium members to high-grade needs or to help establish additional questions to be addressed, and possibly through access to some of their analytical capabilities,” Grammer said. “Some of the consortium members will be sharing data for a reduction in membership subscription.”
Membership is for two years minimum, at $35,000 per year.
“It is already scheduled for at least three years,” Grammer continued. “The minimum two-year buy-in will allow the original members to get third-year data and interpretations at no cost.”
Benefits are expected to flow both ways, Grammer said.
“Graduate students will be intimately involved with the research and will be presenting their findings both at annual meetings for the consortium members to be held here at OSU, but also will be presenting at professional venues such as regional and national AAPG meetings and geological societies,” he said.
“Students will be exposed to real-world issues with firm deadlines and will be utilizing real-world data and state-of-the-art analytical and modeling approaches, equipment – and software,” he said.
“The project as developed is basically a regional exploration to development scale reservoir characterization of several zones in the ‘Mississippian,’ so OSU students will be exposed to all facets of this type of project in a similar manner to what they will be doing in their professional oil and gas careers,” he said.
Grammer provided the following project goals:
♦ Characterization of reservoir types – Establish a comprehensive understanding of the reservoir rock framework through core, sample and outcrop analysis with litho-descriptions, thin sections, SEM, XRD, porosity, permeability and rock mechanics measurements.
♦ Depositional model – Based on rock data define and map depositional facies to understand facies-porosity controls and potential reservoir distribution in the subsurface.
♦ Stratigraphic framework – Establish a sequence stratigraphic framework for the basis of regional correlation and recognition of unconformities that control paleokarst and mineral diagenesis.
♦ Petrophysics – Characterize petrophysical signatures, including sonic velocity measurements for both reservoir and seal facies to establish the predictability of reservoir and non-reservoir facies in the subsurface.
♦ Reservoir development – Evaluate key early and late diagenetic processes that produce or occlude reservoir porosity and permeability; characterize microporosity and nanoporosity, and fracture density.
♦ Reservoir geometry – Map key reservoir zones in relation to unconformities and the Mississippian subcrop.
♦ Geofluids analysis – Determine the timing of generation and migration of petroleum and other geofluids relative to reservoir development.