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Exploitation and Optimization of Reservoir Performance in Hunton Formation, Oklahoma Quarterly Technical Progress Report: April-June 2005

Description: West Carney field--one of the newest fields discovered in Oklahoma--exhibits many unique production characteristics. These characteristics include: (1) decreasing water-oil ratio; (2) decreasing gas-oil ratio followed by an increase; (3) poor prediction capability of the reserves based on the log data; and (4) low geological connectivity but high hydrodynamic connectivity. The purpose of this investigation is to understand the principal mechanisms affecting the production, and propose methods by which we can extend the phenomenon to other fields with similar characteristics. In our experimental investigation section, we continue to describe the use of surfactant to alter the wettability of the rock. By altering the wettability, we should be able to change the water-gas ratio in the reservoir and, hence, improve the productivity from the well. In our Engineering and Geological Analysis section, we present our rock typing analysis work which combines the geological data with engineering data to develop a unique rock characteristics description. The work demonstrates that it is possible to incorporate geological description in engineering analysis so that we can come up with rock types which have unique geological characteristics, as well as unique petrophysical characteristics. Using this rock typing scheme, we intend to develop a detailed reservoir description in our next quarterly report.
Date: July 1, 2005
Creator: Kelkar, Mohan
Partner: UNT Libraries Government Documents Department

Exploitation and Optimization of Reservoir Performance in Hunton Formation, Oklahoma Quarterly Technical Progress Report: July-September 2004

Description: West Carney field--one of the newest fields discovered in Oklahoma--exhibits many unique production characteristics. These characteristics include: (1) decreasing water-oil ratio; (2) decreasing gas-oil ratio followed by an increase; (3) poor prediction capability of the reserves based on the log data; and (4) low geological connectivity but high hydrodynamic connectivity. The purpose of this investigation is to understand the principal mechanisms affecting the production, and propose methods by which we can extend the phenomenon to other fields with similar characteristics. In our experimental investigation section, we present the data on surfactant injection in near well bore region. We demonstrate that by injecting the surfactant, the relative permeability of water could be decreased, and that of gas could be increased. This should result in improved gas recovery from the reservoir. Our geological analysis of the reservoir develops the detailed stratigraphic description of the reservoir. Two new stratigraphic units, previously unrecognized, are identified. Additional lithofacies are recognized in new core descriptions. Our engineering analysis has determined that well density is an important parameter in optimally producing Hunton reservoirs. It appears that 160 acre is an optimal spacing. The reservoir pressure appears to decline over time; however, recovery per well is only weakly influenced by the pressure. This indicates that additional opportunity to drill wells exists in relatively depleted fields. A simple material balance technique is developed to validate the recovery of gas, oil and water. This technique can be used to further extrapolate recoveries from other fields with similar field characteristics.
Date: October 1, 2004
Creator: Kelkar, Mohan
Partner: UNT Libraries Government Documents Department

Exploitation and Optimization of Reservoir Performance in Hunton Formation, Oklahoma Technical Progress Report: October-December 2002

Description: The main objectives of the proposed study are as follows: (1) To understand and evaluate an unusual primary oil production mechanism which results in decreasing (retrograde) oil cut (ROC) behavior as reservoir pressure declines. (2) To improve calculations of initial oil in place so as to determine the economic feasibility of completing and producing a well. (3) To optimize the location of new wells based on understanding of geological and petrophysical properties heterogeneities. (4) To evaluate various secondary recovery techniques for oil reservoirs producing from fractured formations. (5) To enhance the productivity of producing wells by using new completion techniques. These objectives are important for optimizing field performance from West Carney Field located in Lincoln County, Oklahoma. The field, which was discovered in 1980, produces from Hunton Formation in a shallow-shelf carbonate reservoir. The early development in the field was sporadic. Many of the initial wells were abandoned due to high water production and constraints in surface facilities for disposing excess produced water. The field development began in earnest in 1995 by Altex Resources. They had recognized that production from this field was only possible if large volumes of water can be disposed. Being able to dispose large amounts of water, Altex aggressively drilled several producers. With few exceptions, all these wells exhibited similar characteristics. The initial production indicated trace amount of oil and gas with mostly water as dominant phase. As the reservoir was depleted, the oil cut eventually improved, making the overall production feasible. The decreasing oil cut (ROC) behavior has not been well understood. However, the field has been subjected to intense drilling activity because of prior success of Altex Resources. In this work, we will investigate the primary production mechanism by conducting several core flood experiments. After collecting cores from representative wells, we will study the ...
Date: January 1, 2003
Creator: Kelkar, Mohan
Partner: UNT Libraries Government Documents Department

Exploitation and Optimization of Reservoir Performance in Hunton Formation, Oklahoma Quarterly Technical Progress Report: April-June 2003

Description: West Carney Field produces from Hunton Formation. All the wells produce oil, water and gas. The main objective of this study is to understand the unique behavior observed in the field. We would also like to extend the analysis to other similar fields. This report specifically addresses two issues relevant to our understanding of the West Carney reservoir. In the first part, we discuss our efforts to develop the geological model which can help us understand how the depositional environment affects the producing behavior. In the previous Budget Period, we described fourteen cores. In this report, we present preliminary analysis of several additional cores and conodont work. Based on the additional data collected, it is clear that the earlier geological model is simplified and needs to be updated. The complexity in geological environment can explain some of the unusual behavior observed in the field production. The second issue deals with how to develop a model for gauging a potential success of a dewatering project. We have a developed hypothesis regarding what makes it successful, however, we need to test it against the available data. We have started collecting data from other fields producing from Hunton formation so that we can test this hypothesis. In this report, we provide the details of our effort to collect additional information.
Date: July 1, 2003
Creator: Kelkar, Mohan
Partner: UNT Libraries Government Documents Department

Exploitation and Optimization of Reservoir Performance in Hunton Formation, Oklahoma Quarterly Technical Progress Report: January-March 2005

Description: West Carney field--one of the newest fields discovered in Oklahoma--exhibits many unique production characteristics. These characteristics include: (1) decreasing water-oil ratio; (2) decreasing gas-oil ratio followed by an increase; (3) poor prediction capability of the reserves based on the log data; and (4) low geological connectivity but high hydrodynamic connectivity. The purpose of this investigation is to understand the principal mechanisms affecting the production, and propose methods by which we can extend the phenomenon to other fields with similar characteristics. In our experimental investigation section, we present the data on methane injection using huff-n-puff process. It appears that additional oil can be recovered using methane as a solvent. Additional experiments will be needed to confirm our analysis. Our engineering analysis has laid out detailed indicators to make the de-watering successful. Using those indicators, we are currently investigating potential in fill well locations in West Carney field. Our technology transfer activities continued this quarter with two presentations and one workshop.
Date: April 1, 2005
Creator: Kelkar, Mohan
Partner: UNT Libraries Government Documents Department

Exploitation and Optimization of Reservoir Performance in Hunton Formation, Oklahoma Technical Progress Report: July-September 2001

Description: The main objectives of the proposed study are as follows: (1) To understand and evaluate an unusual primary oil production mechanism which results in decreasing (retrograde) oil cut (ROC) behavior as reservoir pressure declines. (2) To develop better, produced water, disposal techniques so as to minimize lifting costs, surface separation costs and water disposal costs. (3) To improve calculations of initial oil in place so as to determine the economic feasibility of completing and producing a well. (4) To optimize the location of new wells based on understanding of geological and petrophysical properties heterogeneities. (5) To evaluate various secondary recovery techniques for oil reservoirs producing from fractured formations. (6) To enhance the productivity of producing wells by using new completion techniques. These objectives are important for optimizing field performance from West Carney Field located in Lincoln County, Oklahoma. The field, which was discovered in 1980, produces from Hunton Formation in a shallow-shelf carbonate reservoir. The early development in the field was sporadic. Many of the initial wells were abandoned due to high water production and constraints in surface facilities for disposing excess produced water. The field development began in earnest in 1995 by Altex Resources. They had recognized that production from this field was only possible if large volumes of water can be disposed. Being able to dispose large amounts of water, Altex aggressively drilled several producers. With few exceptions, all these wells exhibited similar characteristics. The initial production indicated trace amount of oil and gas with mostly water as dominant phase. As the reservoir was depleted, the oil cut eventually improved, making the overall production feasible. The decreasing oil cut (ROC) behavior has not been well understood. However, the field has been subjected to intense drilling activity because of prior success of Altex Resources. In this work, we will ...
Date: October 1, 2001
Creator: Kelkar, Mohan
Partner: UNT Libraries Government Documents Department

Exploitation and Optimization of Reservoir Performance in Hunton Formation, Oklahoma Quarterly Report: Budget Period 2

Description: Hunton formation in Oklahoma has displayed some unique production characteristics. These include high initial water-oil and gas-oil ratios, decline in those ratios over time and temporary increase in gas-oil ratio during pressure build up. The formation also displays highly complex geology, but surprising hydrodynamic continuity. This report addresses three key issues related specifically to West Carney Hunton field and, in general, to any other Hunton formation exhibiting similar behavior: (1) What is the primary mechanism by which oil and gas is produced from the field? (2) How can the knowledge gained from studying the existing fields can be extended to other fields which have the potential to produce? (3) What can be done to improve the performance of this reservoir? We have developed a comprehensive model to explain the behavior of the reservoir. By using available production, geological, core and log data, we are able to develop a reservoir model which explains the production behavior in the reservoir. Using easily available information, such as log data, we have established the parameters needed for a field to be economically successful. We provide guidelines in terms of what to look for in a new field and how to develop it. Finally, through laboratory experiments, we show that surfactants can be used to improve the hydrocarbons recovery from the field. In addition, injection of CO{sub 2} or natural gas also will help us recover additional oil from the field.
Date: February 1, 2005
Creator: Kelkar, Mohan
Partner: UNT Libraries Government Documents Department

Exploitation and Optimization of Reservoir Performance in Hunton Formation, Oklahoma Quarterly Technical Progress Report: January-March 2003

Description: West Carney Field produces from Hunton Formation. All the wells produce oil, water and gas. The main objective of this study is to understand the unique behavior observed in the field. This behavior includes: (1) Decrease in WOR over time; (2) Decrease in GOR at initial stages; (3) High decline rates of oil and gas; and (4) strong hydrodynamic connectivity between wells. This report specifically addresses two issues relevant to our understanding of the West Carney reservoir. By using core and log data as well as fluorescence information, we demonstrate that our hypothesis of how the reservoir is formed is consistent with these observations. Namely, oil migrated in water wet reservoir, over time, oil changed the wettability of some part of the reservoir, oil eventually leaked to upper formations prompting re-introduction of water into reservoir. Because of change in wettability, different pore size distributions responded differently to water influx. This hypothesis is consistent with fluorescence and porosity data, as we explain it in this quarterly report. The second issue deals with how to best calculate connected oil volume in the reservoir. The log data does not necessarily provide us with relevant information regarding oil in place. However, we have developed a new material balance technique to calculate the connected oil volume based on observed pressure and production data. By using the technique to four different fields producing from Hunton formation, we demonstrate that the technique can be successfully applied to calculate the connected oil in place.
Date: April 1, 2003
Creator: Kelkar, Mohan
Partner: UNT Libraries Government Documents Department