When methane is found in water wells near an unconventional well, fingers point to fracturing as the likely suspect. But a study of wells in the Utica Shale named other sources. The Texas Supreme Court ruled late in April that the Railroad Commission of Texas, the state’s oil and gas regulator, does not have exclusive jurisdiction over environmental contamination cases, which can be settled in court.
When methane is found in water wells near an unconventional well, fingers point to facturing as the liklely suspect. But a study of wells in the Utica Shale named other sources. In unconventional plays, comparing the effect of different completion designs or well-management strategies on well performance remains a challenge because of the relatively brief production history and lack of long-term field analogs of these plays.
When fracturing slowed last year in the Marcellus, companies holding produced water they did not need for fracturing paid other operators to take it. It provided a cheap source of fracturing water then, and in the future, water trading could reduce the high cost of shipping water. Antero Resources has built a huge plant to turn waste water into fresh water and salt for sale. The $275-million investment in West Virginia is the most tangible indication of how operators in the Marcellus are pushing water reuse. In this work, the authors perform automatic decline analysis on Marcellus Shale gas wells and predict ultimate recovery for each well.
When methane is found in water wells near an unconventional well, fingers point to facturing as the liklely suspect. But a study of wells in the Utica Shale named other sources. Methane monitoring using improved methods is detecting more gas in the atmosphere, increasing the need for better ways to eliminate releases. With the API and a multi-operator group passing separate programs aimed at reducing methane emissions, the discussions on what defines an acceptable level of regulation continues within the industry. Three experts from different sectors discussed the challenge of methane and regulation at the first panel session of the 2017 SPE Health, Safety, Security, Environment, and Social Responsibility Conference–North America in New Orleans.
The Italian operator reported positive appraisal and exploration results from wells drilled some 10,000 km apart. UK operator Trident Energy is entering Brazil while Australian firm Karoon Energy is expanding its position in the country. Both will try to boost output from already-producing assets. Findings from Kayrros suggest the average Permian well is both less productive and more expensive than reflected in public data. Mexican President Andrés Manuel López Obrador is prioritizing investment in Pemex over foreign participation as a means to boost the country’s shrinking oil output.
The shale sector is studying the results of a 23-well experiment in the southeastern corner of New Mexico to learn what the wider implications might be. Researchers from the Federal Reserve Bank of Dallas quantified the economic impact of the US shale revolution for the first half of this decade. The green light for Santos Energy’s drilling program in the McArthur Basin comes after a moratorium on hydraulic fracturing in the Northern Territory was lifted in 2018. Findings from Kayrros suggest the average Permian well is both less productive and more expensive than reflected in public data. Permian Basin operators and service companies met to discuss completions diagnostics, flowback strategies, water management, and artificial lift strategies.
One of the most important environmental issues of openpit mining is the closure of mine pit lakes. This article from Mining Engineering provides an account by Gerry Stephenson, who was chief mining engineer of Canmore Mines and was instrumental in the reclamation of Canmore Creek Mine pit lakes. With oil and gas facing a talent gap in the wake of the Great Crew Change, the industry finds itself competing for young talent looking for innovative, purpose-driven work. How can energy foster the culture of innovation needed to attract the new workforce, and how does it sell that culture? The updated document offers an introductory overview of the broad topics of oil spill preparedness and response and provides signposting and hyperlinks to a full range of materials from IPIECA and the International Association of Oil and Gas Producers. This paper details the methodology adopted to monitor gas-pipeline leakages using distributed fiber-optic sensing, using an optical fiber as a linear sensor to provide valuable measurement information from all along the fiber itself. It is “one of the world’s largest greenhouse gas mitigation projects ever undertaken by industry,” Chevron said in a news release.
Almost simultaneously, advances were made in understanding both the processes within the source rock organic matter that accompany the generation and expulsion of hydrocarbons and in the acquisition, processing, and quantitative interpretation of 3D seismic data. In particular, as organic matter in shales in unconventional plays generates and expels hydrocarbons, porosity is formed in the organic matter and the organic matter becomes more dense and more brittle. As these changes are occurring at a micro-scale, extraction of hundreds of different attributes from a well-imaged 3D seismic volume has made it possible to observe changes at a macro-scale in seismic lines and horizons within that volume. Seismic attributes derived from pre-stack inversions yielding rock mechanical properties from shear (Vs) and compressional (Vp) velocities and density, when calibrated with well log and/or core measurements, can be combined to calculate TOC, pore pressure, rigidity, and compressibility because these properties cause fundamental changes in how seismic waves travel through the rock.
Equally important, the escalation in computing power via methods such as machine learning, neural networks, and multivariate statistics has made it possible to interpret large amounts of data. All of these innovations have contributed to better identification of sweet spots within unconventional plays. Such sweet spots include areas with elevated TOC values, enhanced porosity, and zones that can be targeted for fracking.
One of the primary advantages of seismic data is that it provides information in those areas in between control points/wells. This information in turn helps operators to better select targets for wells and for landing zones. Carefully tied 3D seismic inversion and integration with petrophysical and rock data further allow for detailed characterization of unconventional reservoirs. The enhanced ability to identify the best potential drilling targets has significant economic implications in terms of risk reduction and improved chances to find economic prospects.
While 3D seismic data is being used routinely by numerous companies to predict the mechanical properties, density, and associated TOC of many formations, there is yet to be a direct link made between TOC loss, kerogen conversion, and the associated changes in rock properties. This work documents the importance of TOC loss during maturation and its effects on rock properties like porosity, density, brittleness, and how those advances coupled with the advances in quantitative interpretation of 3D seismic data are enabling the unconventional operators to predict location, thickness, landing zone, and sweet spots with appropriately acquired, processed, and interpreted 3D seismic. Meticulously calibrated 3D seismic inversion and integration with petrophysical and rock data permit detailed reservoir characterization of unconventional reservoirs.
Updated methods for the back calculation of original TOC have been developed using well logs, rock measurements, and 3D basin modeling to assist in locating and developing unconventional reservoirs. In addition, petrophysical measurements that reflect TOC and porosity and are related to fundamental properties controlling the seismic response can be extracted from the seismic reflection data. In turn, seismic attributes derived from pre-stack inversions yielding rock mechanical properties from shear (Vs) and compressional (Vp) velocities and density, when calibrated with well log and/or core measurements, can be combined to estimate TOC, pore pressure, rigidity, and compressibility because these properties cause basic modifications in how seismic waves travel through the rock.
This study shows advancements in studies of: 1) TOC loss with increased thermal maturation, 2) how this loss affects the development of organic porosity, 3) how kerogen becomes denser, harder, and more brittle with increasing maturity, and 4) how recent developments in quantitative interpretation workflows for 3D seismic data facilitate estimation of TOC and determination of rock mechanical properties from shear (Vs) and compressional (Vp) velocities and density. Further integration of geochemical, geomechanical, and geophysical technologies and measurements will provide improved estimates of present-day TOC that can in turn be extended to relative maturity and percent conversion.
Examples provided in this work illustrate prediction of present-day TOC, porosity, density, and mechanical properties extracted from high fidelity pre-stack inversion. Pre-stack inversion along with machine learning can be used to predict rock properties such as porosity, TOC, organic matter quality, rigidity, and pressure and to correlate those properties back to well productivity for improved execution. Relating present TOC estimated from seismic to TOC loss and kerogen property changes with increasing maturity is possible by combining the results of these technologies.
Though analysis and inversion of painstakingly acquired modern 3D seismic data is capable of estimating porosity, TOC, matrix strength, and pore pressure, the latest work on rock property changes as hydrocarbons mature and are expelled isn't typically addressed in most studies. Increasing communication between disciplines might improve estimation of these properties and extend the capability to assess the extent of TOC loss during maturation and the porosity increases that accompany it. This ability is especially important in the intra-well regions where the potential of 3D seismic to extend data between control points enables better reserve estimates and high grading of acreage. After carefully calibrating a quantitative 3D seismic interpretation with a 3D basin modeling analysis of the source rock potential and maturity, an operator is better prepared to high grade acreage and attain the most economic development of unconventional resources.
The escalation in computing power means there are hundreds of different attributes that can be extracted or calculated from a well-imaged 3D seismic volume. Using quantitative calibration of fundamental geochemical measurements such as TOC, pyrolysis, and petrographic measurements of vitrinite reflectance that yield the quantity, quality, and maturity of organic matter in combination with well log and seismic data creates a model for identifying sweet spots and the areas in the target formation that exhibit high TOC, high porosity, and elevated brittleness. Further integration and calibration of changes occurring at the micro-level in organic matter in unconventional plays with their impact on the signatures of data at the macro-level can provide information on the types of hydrocarbons most likely to be found in these sweet spots as well as identifying which zone(s) in the target formation are most likely to be amenable to fracking. Used together, the advances outlined here result in a technological evolution that could have a substantial impact on: 1) the approach to and 2) the economics of the exploration and production of unconventional plays.