Gevirtz, J., & Ovalle, A. (2017, February 15). Lithofacies Classification for Earth Modeling: Letting the Data Speak For Itself
The new approach to rock typing presented in this paper is compatible with modern earth modeling methods and can improve drilling success by highlighting areas with more favorable rock properties. The sequence in which individual methods are applied is important in this workflow. Assumptions regarding distributional properties of the individual data elements are not required. Experience shows that this workflow provides improved understanding of lithological variation over the volume of interest, increasing the probability of better well performance.
Alcoser, L. A., Ovalle, A., & Parsons, M. C. (2012, January 1). The Bakken: Utilizing a Petroleum System Based Analysis to Optimally Exploit One of the World Largest Basins
The following paper presents an encompassing methodology for analysis of Bakken shale play. This analysis includes; examining reservoir characterization and resource assessments, and evaluating project economics as well as current operators activities. These characteristics and assessments are then used to better understand and put context around the current drilling and completion best practices as well as water handling and operational constraints. The paper thoroughly analyzes the prolific Bakken petroleum system and describes the successful application of technologies and efficient operating practices that have enabled current Bakken production to increase to the cusp of the 500,000 BOPD mark.
Ronderos, J. R., & Ovalle, A. P. (2010, January 1). Geomechanical Modeling Techniques Applied to Waste Injection Process
This paper explains the engineering Waste Injection (WI) assurance process and shows examples where its application successfully supports the development of major drilling projects where WI was a critical part of the operation. The methodology followed by the process gives the tools to manage responsible and safely a permanent disposal of the drilling waste while maintaining drilling pace and schedules. The process begins with a full feasibility study FEED where accurate geomechanical modeling is required to define the optimal operational conditions to achieve success during the injection, disposal formation, containment zones, capacity, and operational parameters are defined in the study. The next stage is the calibration of the model with a full injectivity test into the target formation. Once the injection operation begins, monitoring injection and decline pressures allows total control and verification of the injection parameters to maintain control of the waste disposal domain. Injection pressure analysis, during and post injection, determines how the fracture system is behaving as WI progresses. Recalculation of the main geomechanical formation parameters based on the formation pressure response needs to be conducted in order to obtain accurate forecast of the disposal domain and formation capacity. As conclusion, more than 28 MM bbls of waste have been successfully injected worldwide, reducing considerably the impact to the environment compared to conventional disposal options.
Ovalle, A. P., Ronderos, J. R., & Simmons, S. L. (2009, January 1). Waste Injection: The Environmentally Safe and Cost-Effective Solution for Ultimate Waste Disposal
Waste Injection (WI) into sub-surface formations has proven to be the most effective technology for final disposal of wastes from oil and gas drilling and production that provides a secure operation achieving zero discharge. WI achieves this by storing the injected material several meters below surface in hydraulically created fractures, avoiding surface environmental risks and future liabilities for operating companies. This paper presents the methodology based on risk analysis, supported by successful worldwide case histories, to prepare an operational and cost-efficient operation that continuously analyzes information and provides fit-for-purpose recommendations to achieve a seamless injection process. The Assurance Waste Injection process permits the detection and identification of potential risks giving mitigation options to prolong the life of the injector.
Ji, L. L., Shokanov, T. A., Fragachan, F. E., Ovalle, A., & Ronderos, J. (2009, January 1). Multi-Fracture Complexities In Drilling Waste Injection: Wagon-Wheel Uniform Disposal Domain Or Secondary Fracture Branching
This paper presents a mathematical study of stress changes in principal horizontal and vertical stresses around the fracture due to an existing fracture using the Sneddon and Illiott model. The study shows that significant stress changes only occur in a localized near-fracture region, and far-field stresses have been minor influenced. Wellbore pressures to initiate a fracture at different potential locations and orientations are analyzed, too. The analysis shows the potential location of fracture opening/propagation is reopening of or branching from the old fracture away from wellbore. Wagon-wheel multi-fracture disposal domain is mathematically confirmed as impractical by computational investigation on stresses increase or fracture width around the wellbore for two types of assumed wagon-wheel (uniform strain and uniform width) multi-fractures. Creation of wagon-wheel multi-fractures would either require an impractical wellbore pressure to overcome the extreme stress due to existing fractures or the fracture width would vanish at the wellbore. This paper also reanalyzes the data from large-scale Mounds experiments of a series of cuttings reinjection and identifies that vertical fracture growth and branching from old fractures away from the wellbore occur more possibly according to the most microseismic events and tiltmeter patterns. This also confirms the above theoretical analysis and conclusions.
Ovalle, A. P., Simmons, S. L., Shokanov, T. A., Ronderos, J. R., & Benelkadi, S. (2009, January 1). Improved Waste Injection Monitoring and Modified Operational Procedures: The Keys to Prolong the Well Storage Capacity
This paper presents the unique and technically challenging injection monitoring and pressure interpretation experience attained in different WI projects worldwide, where the in-depth interpretation of fracture behavior helped as a risk-prevention tool with mitigation options applied to operational parameter well specifics. The continuous monitoring of injection data and parameters assists in developing a well history and a prediction mechanism for well storage capacity, extending the life of the injector and maximizing efficiency for the development of the field.
Fetsenets, R., Ovalle, A., Still, V., Blyus, D., Shokanov, T. A., & Anokhin, V. V. (2009, January 1). Meeting the Challenges of Waste Disposal in the Mainland of Russia - Successful Design and Implementation of the First Full-Scale Drilling Waste Injection Project in Western Siberia
A joint effort between a major oil company in Russian and a waste management service company selected Waste Injection (WI) technology as the most efficient, economical and environmentally friendly way to handle the drilling waste in the field. Waste Injection is a relatively new waste disposal methodology used in Russia, although the first injection job on a worldwide basis was in 1991. The first Russian WI operation was successfully implemented in 2004 on offshore projects near Sakhalin Island. Since that time and until October 2008, WI had only been used on several offshore platforms. The need of a robust technology for waste management on the South Priobskoe field was the departure point for implementing WI in mainland Russia. The following paper describes the steps taken to implement WI on land projects in Russia as the technology that allows for zero discharge, ensuring a safe and permanent drilling waste disposal performed under strict regulations and minimizing associated transportation and cost risks.
Gumarov, S., Ovalle, A. P., Shokanov, T. A., Park, G., & Simmons, S. L. (2009, January 1). Evaluation of Extended Seawater Injections Impact on Waste Injection Pressure Response and Waste Disposal Capacity
This paper introduces a new approach to a regular seawater injection by investigating the relationship between pressure behavior and seawater injection. Displacement of slurry from the tubing by seawater over flush is carried out routinely in WI operations worldwide. However, never before it was considered as a pressure maintenance tool. The authors describe the impact of continuous seawater injection on injection pressure through the lifetime of three waste injectors. The injection pressure behavior before, during and after continuous seawater injection was reviewed using downhole measured data. It was noticed that regular seawater over-displacements during the continuous time periods between slurry injections reduced injection pressure considerably. Consequently, a thorough evaluation was initiated to investigate the impact of extended seawater injection on in-situ stresses and its potential advantage in maintaining the injection pressure within lower limits. Considering the novelty and value of study for expanding worldwide WI operations, this paper presents the new approach to seawater injection as an injection pressure and disposal capacity maintenance tool.
Shokanov, T., Still, V., Hernandez, E., Anokhin, V., Ovalle, A., & Fragachan, A. (2008, January 1). Subsurface Drilling Waste Injection: Real-time Waste Domain Characterization Using Injection Monitoring and Pressure Interpretation (Russian)
This paper presents the unique and technically challenging injection monitoring and pressure interpretation experience attained in different waste injection projects in the CIS region, where the in-depth interpretation of fracture behavior and waste domain monitoring helped to minimize subsurface risks and to provide an adequate level of subsurface assurance. Continuous monitoring of injection data and parameters by a group of geo-mechanical experts in close collaboration with the operational team helps to identify and minimize the sub-surface risks and generate appropriate recommendations and mitigation procedures to avoid potential injectivity failures. Currently more than one and a half million barrels of drilling waste have been successfully contained through various waste injection projects in the CIS region.
Ovalle, A. P., Shokanov, T. A., Simmons, S. L., & Ronderos, J. (2008, January 1). Field Implementation of Sub-Surface Waste Injection: An integrated approach for field disposal perspective
As the world faces new challenges to protect the environment from all human-generated wastes, self-imposed industry policies as well as governmental regulations support new green policies towards implementing best, not necessarily least costly, practices to prevent any environmental damage due to spillage during operations. Waste Injection (WI) has been selected as the preferred methodology of final disposal of oilfield wastes, including cuttings, produced water, drilling fluids and tank bottoms, etc., by many operators and legislators because it achieves zero discharge in a safe and efficient manner at a lesser operating cost than comparable proven technologies. This may be particularly true for large-scale projects. Mexico, Argentina, Azerbaijan, USA, UK, Norway, Russia and other countries have strategically implemented WI operations in field developments because they comply with local laws and they avoid future liabilities as wastes are permanently isolated and stored below surface. The development and implementation of such technology in large-scale projects is carefully designed using a risk-based analysis that is comprised of fracturing studies of the area of injection, technologies integration, logistics, equipment specification and process monitoring, all with the aim of performing a seamless and risk-free operation. The following paper addresses planning and implementation methodology for WI operations with real examples that demonstrate the value of proper preparation and integration of various technologies to attain maximum efficiency under QHSE standards.
Ovalle, A. P., Lenn, C. P., & McCain, W. D. (2007, December 1). Field Implementation of Sub-Surface Waste Injection: An integrated approach for field disposal perspectiveTools To Manage Gas/Condensate Reservoirs; Novel Fluid-Property Correlations on the Basis of Commonly Available Field Data
Certain fluid properties are required for studies related to management of gas/condensate reservoirs or prediction of condensate reserves. Often these studies must begin before laboratory data become available, or possibly when laboratory data are not available. Correlations to estimate values of these properties have been developed that are based solely on commonly available field data. These properties are the dewpoint pressure of the reservoir fluid, changes in the surface yield of condensate as reservoir pressure declines, and changes in the specific gravity of the reservoir gas as reservoir pressure declines. No correlations based solely on field data have been published for any of these properties. The field data required are initial producing gas/condensate ratio from the first-stage separator, initial stock-tank liquid gravity in °API, specific gravity of the initial reservoir gas, reservoir temperature, and selected values of reservoir pressure. The dewpoint pressure correlation is based on data of 615 samples of gas condensates with worldwide origins. The other two correlations are based on 851 lines of constant-volume-depletion data from 190 gas-condensate samples, also with worldwide origins.
Guo, Q., Geehan, T., & Ovalle, A. P. (2007, June 1). Increased Assurance of Drill Cuttings Re-Injection - Challenges, Recent Advances and Case Studies
This paper describes the challenges faced in CRI projects, along with recent advances and experiences gained in tackling these challenges through modeling, cuttings slurry and operational procedure design, monitoring and verification. For example, much progress has been made recently in slurry rheology design and operational procedure selection such as suspension/displacing to avoid loss of injectivity and to maximize disposal capacity and minimize HSE issues. The authors also will present a risk-based approach, which integrates deterministic software and tools, available data, knowledge and experience, for modeling of geological and operational uncertainties and potential risks to increase the quality assurance. Case examples will be presented to illustrate the value of this integrated approach. Best practice guidelines and recommendations will be provided on data collection, design and engineering, operation and monitoring.
Shokanov, T. A., Nolte, K. G., Fragachan, F. E., Ovalle, A. P., & Geehan, T. (2007, January 1) Waste Subsurface Injection: Pressure Injection and Decline Analysis. Society of Petroleum Engineers
This paper describes the results of pressure analysis conducted in injection wells, successfully utilized for Cuttings Re-Injection (CRI) and disposal of produced water because of a close monitoring of pressure injection and decline, in spite of the risky conditions. Abnormal pressure increases, and restrictions observed during injection were mitigated via engineered diagnostics. This paper also describes the interpretation and methodology implemented to maintain safe injection assurance via regular pressure analysis until pressures reached values above overburden indicating need for associated risk assessment, including potential breach to the surface. Characterizing the disposal domain using injections monitoring and in-depth pressure analysis is a major step to enhance mitigation of waste environmental protection risks posed by CRI. Past interpretations of waste domain, appear to be in conflict with rock mechanics, hydraulic fracturing and general physics principles.
Alba Rodriguez, A., Fragachan, F. E., Ovalle, A., & Shokanov, T. A. (2007, January 1) Environmentally Safe Waste Disposal: The integration of Cutting Collection, Transportation and Re-Injection
This paper addresses the success of integrating methodologies for containing, handling, and transporting drill cuttings from several drill sites to a unique CRI well, where wastes are injected for final and responsible disposal. Case histories of several sites around the world are presented as they used different process configurations to achieve the common final objective: a cost-effective and environmentally friendly solution for waste management.
Fragachan, F. E., Shokanov, T. A., Ovalle, A. P., & Nolte, K. G. (2007, January 1) Mitigating Risks From Waste Subsurface Pressure Injection and Decline Analysis
This paper describes the solution and detailed pressure monitoring methodology implemented to main safe injection assurance via regular disposal fracture diagnostics. Timely identification and a thorough evaluation of non-ideal pressure signatures observed during injection and post shut-in period provided critical information required to detect subsurface risks identification and characterization. The application of comprehensive fracture-mapping techniques is a major step in mitigating the environmental risks posed by waste. Waste mapping represents valuable information, not only in the overall planning of drilling operations, but in the fundamental and invaluable need to provide sound engineering for waste location and fracture containment assurance, thus minimizing environmental impact. Previous, oversimplified interpretations of multiple fracturing systems (or so-called uniform disposal domain) and new fracture initiation process are demonstrated to be in apparent conflict with fracture mechanics, stress calculations and the general principles of physics.
Fragachan, F. E., Ovalle, A. P., & Shokanov, T. A. (2006, January 1) Pressure Monitoring: Key for Waste Management Injection Assurance
This paper describes the outcome of pressure analysis successfully used for Cuttings Re-Injection (CRI) and disposal of produced water resulting from closely monitoring pressure injection and decline. It addresses proper root-cause engineering diagnostic processes that were implemented during abnormal pressures increases and restrictions observed during annulus injection in North Sea projects. Severe risks were mitigated with injection pressures observed, on occasion above overburden, to maintain safe injection assurance. A methodology was developed and implemented, as a result of process mapping based on signature pressures from pressure decline. Their characterization represents a major step in mitigating risks posed by waste injection, providing not only engineering understanding valuable to overall drilling operations planning, but also minimizing potential environmental impact with sound engineering subsurface waste management.
Ovalle, A. P., Lenn, C. P., & McCain, W. D. (2005, January 1) Tools To Manage Gas/Condensate Reservoirs: Novel Fluid-Property Correlations Based on Commonly Available Field Data
Certain fluid properties are required for studies related to management of gas condensate reservoirs or prediction of condensate reserves.Often these studies must begin before laboratory data become available or possibly when laboratory data will not become available.Correlations to estimate values of these properties have been developed based solely on commonly available field data. These properties are (1) the dewpoint pressure of the reservoir fluid, (2) changes in the specific gravity of the reservoir gas as reservoir pressure declines, and (3) changes in the surface yield of condensate as reservoir pressure declines.No correlations for any of these properties based on field data have been published. The field data required are initial producing gas-condensate ratio from the first stage separator, initial stock-tank liquid gravity in oAPI, specific gravity of the initial reservoir gas, reservoir temperature, and selected values of reservoir pressure. The dewpoint pressure correlation is based on data of 615 samples of gas condensates with worldwide origins.The other two correlations are based on 851 lines of constant volume depletion data from 190 gas condensate samples, also with worldwide origins.
Guo, Q., Geehan, T., & Ovalle, A. (2004, January 1) Increased Assurance of Drill Cuttings Re-Injection - Challenges, Recent Advances and Case Studies
This paper describes the challenges faced in CRI projects, along with recent advances and experiences gained in tackling these challenges through modeling, cuttings slurry and operational procedure design, monitoring and verification. For example, much progress has been made recently in slurry rheology design and operational procedure selection such as suspension/displacing to avoid loss of injectivity and to maximize disposal capacity and minimize HSE issues. The authors also will present a risk-based approach, which integrates deterministic software and tools, available data, knowledge and experience, for modeling of geological and operational uncertainties and potential risks to increase the quality assurance. Case examples will be presented to illustrate the value of this integrated approach. Best practice guidelines and recommendations will be provided on data collection, design and engineering, operation and monitoring.