Petrotechnical Resources of Alaska, LLC (PRA) is an integrated oil and gas consulting firm in Anchorage, Alaska, specializing in oil and gas exploration and development projects all over Alaska. PRA is recognized as having great strengths in many aspects of oil and gas activities, including: geology; geophysics; petrophysics; drilling, completion, production, facilities, process; and civil engineering. We also have tremendous strength in the areas of regulatory process, including permitting, compliance, and stakeholder relations. PRA’s consultants have extensive contemporary experience and knowledge of permitting, planning and executing complex and diverse projects throughout Alaska, with particular focus on the North Slope. PRA is highly respected in the industry, native community, and government agencies for maintaining the highest level of professional, technical and ethical standards attainable.
PRA is recognized as a partner and major contributor, capable of enabling cooperative and valuable solutions to diverse client needs. Summaries of a number of PRA projects are described in detail below.
Methane Hydrate Research on the North Slope
(North Slope Borough, AK)
DOE, NETL, USGS, JOGMEC
Petrotechnical Resources of Alaska (PRA) is in the distinctive position of having worked on the implementation of the plan to conduct a Methane Hydrate Long-Term Production Test on the Alaska North Slope since April 2015. Collaboratively with the United States Department of Energy (DOE), National Energy Technology Laboratory (NETL), the United States Geological Survey (USGS) and the Japan Oil, Gas and Metals National Corporation (JOGMEC), PRA successfully planned and executed the drilling of the Stratigraphic Test Well (Hydrate-01) at the Prudhoe Bay Unit (PBU) 7-11-12 gravel pad site. Hydrate-01 was completed with downhole sensors (Distributed Temperature Sensors and Distributed Acoustic Sensors) and continues to serve as the first of two monitor wells for the Project. Significant geologic, seismic and reservoir studies conducted by PRA led to the completion of Hydrate-01, which established the 7-11-12 site as “world-class” for a gas hydrate-bearing reservoir.
Within this project, PRA acquired the data license for the available seismic in the area. The PRA team has combined experience of over 40 years in the study and drilling of hydrate wells on the North Slope of Alaska and has collectively worked on every hydrate study in the State of Alaska over the last 20 years.
North Slope Borough Gas Field
North Slope Borough (NSB)
PRA managed a major gas field upgrade project for the North Slope Borough (NSB), including the design, permitting, procurement, and construction management for five new horizontal gas production wells, and facility upgrades for the East Barrow Gas Field and Walakpa Gas Field in Barrow Alaska. This work involved extensive reservoir modeling prior to design of the upgrades to increase gas field production capacity. PRA gathered all available seismic data covering the fields and interpreted and integrated the seismic data with well log data from the two fields in order to create a detailed reservoir characterization model. Dynamic reservoir modeling was completed for the history match, and predictive modeling was completed to demonstrate the benefit of additional wellbore capacity. Material balance and decline curve analysis were also incorporated in the study to understand the influence of in-situ methane hydrate saturation and dissociation in the two fields. Ongoing studies include regular pressure monitoring and associated decline curve analysis to estimate remaining reserves in the two fields.
The most significant component of this project, for the Alaska Gas Hydrate Production Test Well Design and Test Plan, was the research program funded jointly by the U.S. Department of Energy- NETL and the NSB. The objective was to prepare a research management plan; establish a context for the study based on prior and ongoing research; model the hydrate stability zone associated with the three Barrow Gas fields; characterize the reservoir properties; model production characteristics of the fields; and select an optimum hydrate test well location in Barrow. Modeling work was completed supporting the existence of methane hydrates in association with the gas fields. The project included sampling and analysis of produced gas; determination of temperature and pressure gradient; and modeling of hydrate stability. Although the DOE, due to the financial crisis, had to pull funding prior to the execution phase, a detailed reservoir characterization was completed: supporting the simulation of hydrate production methodologies, quantifying the hydrate resource, and facilitating the selection of an optimum location for a methane hydrate test well.
Placer Exploration (North Slope Borough, AK)
Arctic Slope Regional Corporation (ASRC)
The drilling of the Placer well on the North Slope of Alaska is another example of PRA's ability to design and execute an exploration program in a remote location. On behalf of our client, Arctic Slope Regional Corporation (ASRC), PRA's multi-discipline team of oil and gas professionals designed and implemented the successful program over a very limited drilling window and did so under budget. Additionally, the project required the construction of a 12-mile ice road. At the completion of the drilling component, the PRA team designed and implemented a field production facility to accomplish a well test that led to the certification of the exploration well with the State of Alaska.
A key design issue faced by this project was a high-pressure shallow interval. The wells penetrated the Kuparuk Formation at the Placer Unit, and to get to the reservoir interval, the wellbores had to pass through the higher pressure Miluveach Shale. The seismic analysis of the extent and thickness of this shallow drilling hazard was a key component leading to the success of the drilling program.
(Cook Inlet, AK)
PRA technical professionals have extensive experience working on the Cook Inlet Natural Gas Storage Alaska (CINGSA) Project, a natural gas storage facility constructed to provide peaking capacity for the energy utilities in Southcentral Alaska. The facility utilizes a 26 BSCF depleted natural gas reservoir in the Cook Inlet Basin, known as the Sterling C Fm. in the Cannery Loop Unit. PRA was engaged by CINGSA to design and manage drilling and completion of the five horizontal gas wells used for injection and offtake of natural gas from the reservoir. After successful drilling and completion of the wells and construction of the facility, PRA has supported surveillance and modeling of the reservoir, constructing and maintaining detailed reservoir characterization and simulation models for the field. This work has supported operation of the facility, as well as strategic planning for expansion and wellwork options to optimize injection/offtake capacity.
The CINGSA gas storage facility is penetrated by 17 wells: 12 legacy exploration and development wells, and the 5 dedicated gas injection/offtake wells. PRA has built a sophisticated reservoir model integrating well log, seismic, and reservoir surveillance data characterizing the field. PRA professionals used the Landmark GeoGraphix Discovery Suite for well log and seismic interpretation and modeling, supplemented by Hampson-Russel amplitude versus offset (AVO) modeling tools for characterization of depositional and pore fluid geometries. PRA utilized Roxar RMS 3D modeling software to integrate well log and seismic interpretation models into a three-dimensional reservoir model. This model is updated as new information becomes available (updates to well logs, updated seismic volumes or interpretation, reservoir surveillance information). The RMS model is used in reservoir simulation modeling for history match and predictive modeling. PRA currently uses Computer Modeling Group's CMG-STARS for this reservoir simulation.
Shallow Drilling Hazards
(North Slope, AK)
PRA executed a seismic analysis to identify potential shallow drilling hazards for the proposed WINX-1 well location in the North Slope of Alaska. This is a key analysis that will be necessary in the planning of The Project.
The Nanuq 3D seismic data was processed through Pre-Stack Time Migration (PSTM). The Nanuq-3D reflectivity volume, the full stack volume, angle stack volumes, and similarity (coherence) volumes were used to investigate structure, faulting, and offset amplitude behavior in the shallow section above 1000ms. Drilling history and mud weight vs. depth data from the Cronus-1 well were used in reviewing shallow gas risk and estimating pore pressure for the WINX-1 well location.
Three potential areas were identified in the shallow section as potential drilling hazards.
- A potential shallow fault at 490ms (1650ft)
- The shallow hazards risk for loss fluids during was considered `low'
- Chaotic Channel Fill of Mid Schrader Bluff Channel at 590ms (2090ft)
- The shallow hazards risk at this level was considered `low to moderate'
- High amplitude soft sands at 680ms (2460ft)
- Soft channel sands are associated with a fine grained, low energy marine highstand system were deemed unlikely to cause major losses, however due to the high amplitudes it is possible there may be shallow gas associated with these sands; the shallow hazard risk at this level was considered to be `low to moderate'
This study highlights the strengths of the PRA geophysical team integrated with a strong understanding of potential drilling hazards and mitigation planning.
Petrotechnical Resources of Alaska (PRA), acting as an agent for the native Corporation Ahtna, designed, drilled, and completed a well in the Glennallen Basin in Central Alaska. This exploration project was an attempt to find gas for local energy consumption. The drilling location was remote and involved logistical challenges. The design of the drilling project had to account for very challenging high-pressure intervals.
This project, like all of the PRA design and drilling programs, required all of the pertinent permits and approvals under State of Alaska regulations. Our diverse multi-technical teams have extensive knowledge and experience in every facet of designing and implementing a drilling and production facility program. Our key engineering personnel are registered, licensed engineers with the State of Alaska, as well as PRA is a licensed Petroleum Engineering firm.
Linc Energy Ltd
PRA designed and drilled two exploration wells for Linc Energy Ltd in the winter season of 2013 and 2014. The remoteness of the Umiat oil field combined with the reservoir's complex geology and the shallow formation made this project a challenge. The interval of interest, the Grandstand, occurs in the base of and below the permafrost. PRA successfully drilled the first horizontal well ever drilled in the remote field. The complex design of the completion strategy in combination with the horizontal wellbore opened this field to the possibility of achieving development.
The drilling experience, in the base of the permafrost is another example of PRA's experience with shallow formations on Alaska's North Slope. Our learnings and successes of drilling and producing in the North Slope's permafrost interval gives PRA a unique North Slope understanding. Additional to the drilling, seismic interpretation of the reservoir in and below the permafrost was required. Further PRA petrophysical studies of this unique near frozen reservoir helped the client understand and propose a development plan.
(North Slope, AK)
Oil Search Alaska (OSA)
PRA performed studies for Oil Search Alaska (OSA) to determine first: the viability of sourcing water for waterflooding the Nanushuk reservoir from initial production through end of field life, and second: to evaluate disposal well options for the drilling phase of development of Pikka.
The water sourcing study exemplified PRA's ability to assemble a team of geologists, geophysicists, petrophysicists and petroleum engineers to execute screening studies. The results identified source water options within the client's leases and in the surrounding areas based on a best fit from a geological and petrophysical analysis. The team performed significant work with modeling rate potential, volumetric estimates, analog review, development planning, and completion design for potential sources. The team further integrated a core flood study highlighting that significant incremental recovery could be realized through low salinity flooding. Mapping of the depth of the permafrost, and depths to top Ugnu and West Sak Fm., was conducted to determine how far east unfrozen low salinity source water was available with high production rate and volumetric potential. This work, overlaid on surface roads, pads, pipelines, and facilities maps, provided convergence on a suitable location for water source wells.
The disposal well study highlighted the geophysical strengths of the PRA team. A review of the shallow and deep reservoirs was undertaken for applicability of these horizons for disposal. Extensive review of the faults and their ability to seal was studied. The challenges of geophysical interpretation in shallow formations due to the layer of permafrost across the North Slope is significant. The Gas Hydrate production test well will be drilled into the permafrost horizon. The effective and precise ability to interpret seismic in and around permafrost is a key strength in PRA's portfolio.
Furie Offshore Drilling Program
(Kenai, AK - Offshore)
Furie Operating Alaska, LLC
PRA was hired to support Furie Operating Alaska, LLC in the Kitchen Lights Unit with operations to meet gas contract commitments in Cook Inlet Basin, AK. This project consisted of the planning and execution of drilling wells and completing workovers, and involved engineering, geoscience, permitting, procurement, contracting, compliance, safety, and field operations. PRA planned equipment and executed service contracts to carry out all aspects of the well-drilling operations and workover operations, up to and including well tie-in and production startup.
The project scope included conceptual design, final design and written procedures for four well programs. PRA managed the planning, procurement, permitting, operations, safety and regulatory compliance aspects of the project, and vetted invoices for Furie approval and payment.
PRA integrated the available well and seismic data for Kitchen Lights Unit in order to identify the optimal location for the KLU-A4 well, with the goal of maximizing stacked pay in the Beluga and Sterling Formations, while targeting sweet spots in the fluvial channel geometry to improve access to reserves and increase drainage area. Well workover programs for KLU-1, KLU-3, and KLU-A2A were designed, permitted, procured and completed.
The Kitchen Lights Unit is located within the Cook Inlet north of the Forelands. The closest city is Nikiski, Alaska. Drilling and workover operations utilized a mobile offshore drilling unit (a jack-up rig); the Cook Inlet regularly experiences high current during both flood and ebb tides. Logistics management included contracting boats, shore base management, and helicopter scheduling and management.
Reprocessing Vintage 2D Seismic on the North Slope
The United States Geological Survey (USGS)
PRA was awarded the contract to reprocess vintage, two dimensional (2D) seismic reflection data from the Alaska North Slope. Work included reprocessing of ~1,700-line miles of 2-D seismic reflection data collected during 1984 (dynamite and vibroseis sources) and 1985 (vibroseis source). Department of the Interior Secretarial Order 3352 directs the USGS to conduct updated assessments of undiscovered, technically recoverable oil and gas resources of the Alaska North Slope. Seismic reflection data is the main tool for interpreting subsurface geology and for evaluating the potential of the Arctic National Wildlife Refuge (ANWR). Across much of these unexplored or lightly explored areas, only vintage 2-D seismic reflection data, collected 20 to 70 years ago, is available. The United States Geological Survey (USGS) contracted PRA to reprocess selected portions of the vintage 2-D seismic reflection data with the objective to enhance the resolution of the data and facilitate improved interpretation of subsurface rock formations.
Based on discussions with USGS project owners and on the initial review of selected shot records, PRA developed a tailored processing flow diagram, with a base plan and iterative loops for QC and flow modification. PRA reviewed the acquisition parameters and built on the two prior processing projects using current state-of-the-art technologies. PRA met with the USGS team immediately upon project kick-off to ensure alignment of project objectives, schedule and workflow. PRA managed the subcontractor and provided in-house technical oversight and quality assurance.