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Johnson, Andrew C. (Schlumberger) | Miles, Jeffrey (Schlumberger) | Mosse, Laurent (Schlumberger) | Laronga, Robert (Schlumberger) | Lujan, Violeta (Schlumberger) | Aryal, Niranjan (Schlumberger) | Nwosu, Dozie (Schlumberger)
Abstract Formation water saturation is a critical target property for any comprehensive well log analysis program. Most techniques for computing saturation depend heavily on an analyst’s ability to accurately model resistivity measurements for the effects of formation water resistivity and rock texture. However, the pre-requisite knowledge of formation water properties, particularly salinity, is often either unknown, varying with depth or lateral extent, or is difficult to derive from traditional methods. A high degree of variability may be present due to fluid migration from production, water injection, or various geological mechanisms. In unconventional reservoirs, the complexity of the rocks and pore structure further complicates traditional interpretation of the available well logs. These factors introduce significant uncertainties in the computed fluid saturations and therefore can substantially affect final reserves estimates. A novel technique in geochemical spectroscopy has recently been introduced to distinguish the chlorine signals of the formation and borehole. The new, quantitative measurement of formation chlorine enables a direct calculation of bulk water volume for a given formation water salinity. When integrated into a multi-physics log analysis workflow, the chlorine-derived water volume can provide critical information on fluid saturations, hydrocarbon-in-place, and producibility indicators. This additional information is especially useful for characterizing challenging and complex unconventional reservoirs. We present the new technique through several full petrophysical evaluation case studies in organic shale formations across the U.S., including the Midland, Delaware, Marcellus, and DJ basins. We solve for formation-specific water salinity and bulk water volume through an optimization that combines chlorine concentration with resistivity and dielectric measurements. These outputs are integrated into comprehensive petrophysical evaluations, leveraging a suite of advanced well log measurements to compute final fluid and rock properties and volumetrics. The evaluations include geochemical mineralogy logs, 2D NMR analyses, dielectric dispersion analyses, basic log measurements, and multi-mineral models. The results underscore the utility of the new spectroscopy chlorine log to reduce petrophysical model uncertainties in an integrated workflow. While this workflow has been demonstrated here in several U.S. organic shale case studies, the fundamental challenges it addresses will make it a valuable solution for a range of unconventional reservoirs globally.
Colorado oil production is surging to record levels, outpacing the other major producing US states in year-over-year gains on the backs of the steady-and-predictable Denver-Julesburg (DJ) Basin and overlapping Niobrara Shale. As overall US oil output continues to surge, attention has been drawn to the Permian Basin and SCOOP and STACK plays. Operators have flocked to West Texas, southeastern New Mexico, and central Oklahoma to stake claims to land they believe will usher them into a new, leaner era for the industry. The expansive Permian alone, which covers more than 75,000 sq miles, has accounted for the bulk of US oil production increases and mergers and acquisitions over the last couple of years. Although they are intertwined and together encompass parts of Colorado border states Wyoming, Nebraska, and Kansas, the DJ and Niobrara offer a fraction of the acreage and prospective resources of the Permian.
Years in the making, the recent steady rise in drilling in the Powder River Basin of northeast Wyoming is generating excitement reminiscent of the early days of currently more-established US onshore oil plays. The upturn in activity is resulting in double-digit production growth. Wells are bubbling over with oil, and operators are bubbling over with enthusiasm. This has been most evident in recent industry presentations, where decision makers from the basin's exclusive club of operators have gushed over what is becoming a core asset in their portfolios. Given the basin's oil richness, multiple stacked horizons, and well performance and economics, "we think it's comparable and competitive with the big-name basins--whether it's the Permian, SCOOP, or STACK," Joseph DeDominic, president and chief operating officer of Anschutz Exploration, said at a recent SPE Gulf Coast Section meeting on the basin.
Colorado voters soundly defeated a measure 6 November that would have restricted the vast majority of new development in the country's fifth largest oil-producing state. The outcome was a big relief for the oil and gas industry, but its existential fight in the state hasn't ended. Proposition 112 would have required new oil and gas development in Colorado to be at least 2,500 ft from areas considered "vulnerable," including homes, schools, and waterways. The current minimum setback is 500 ft. With more than 90% of precincts reporting, about 57% of the electorate voted against the measure.
Pei, Yanli (The University of Texas at Austin) | Yu, Wei (The University of Texas at Austin / Sim Tech LLC) | Sepehrnoori, Kamy (The University of Texas at Austin) | Gong, Yiwen (Sim Tech LLC / The Ohio State University) | Xie, Hongbin (Sim Tech LLC) | Wu, Kan (Texas A&M University)
The extensive depletion of the development target has triggered the demand for infill drilling in the upside target of multilayer unconventional reservoirs. To optimize the hydraulic fracturing design of newly drilled wells, we need to investigate the stress changes in the upside target induced by parent-well production. In this work, an integrated parent-child workflow is presented to model the spatial-temporal stress evolution and propose the optimal development strategy for the upside target using a data set from the Permian Basin. The stress dependence of matrix permeability and fracture conductivity is determined based on available experimental data and incorporated in our reservoir simulation with the aid of an embedded discrete fracture model (EDFM). With calibrated reservoir properties from history matching of an actual well in the development target (i.e., 3rd BS Sand), we run the finite element method (FEM) based geomechanics simulator to predict the 3D spatial-temporal evolution of the local principal stresses. A displacement discontinuity method (DDM) hydraulic fracture model is then applied to simulate the multi-cluster fracture propagation in the upside target (i.e., L2BSSh) with the updated heterogeneous stress field. Numerical results indicate that stress field redistribution associated with parent-well production not only occurs within the development target but also vertically propagates to the upside target. A smaller parent-child horizontal offset induces a severer deviation of child-fractures towards the parent wellbore, resulting in more substantial well interference and less desirable oil and gas production. The parent-child fracture overlapping ratio in our study is in 0.6 ~ 0.8 for the 400 ft horizontal offset and 0.2 ~ 0.5 for the 600 ft horizontal offset. Varying the parent-child vertical offset gives the same trend as we change the horizontal offset. But with a delayed infill time, placing child-well in different layers causes more significant variation in the ultimate recovery. Moreover, infill operations at an earlier time are less affected by parent-well depletion because of the more homogeneous stress state. The candidate locations to implement infill-wells are suggested in the end for different infill timing by co-simulation of the parent-child production. With the reservoir-geomechanics-fracture model, this work provides a general workflow to optimize the child-well completion in multilayer unconventional reservoirs. The conclusions drawn from this study are of guiding significance to the subsequent development in the Permian Basin.
The story of the US shale revolution is well known. Hydraulic fracturing techniques were executed by Mitchell Energy in vertical Barnett Play gas wells in the early 2000's, vertical wells matured into horizontal multi-stage frac wells, and one of the largest land leasing campaigns in history exploded as operators chased high gas prices.
As the natural gas market became saturated, the industry started to strip the natural gas liquids (NGLs) out of the gas stream to take advantage of the ever-rising oil pricing. When gas prices tumbled in 2011, and oil prices climbed north of $100/bbl, the industry looked to the liquid rich/oil plays, such as the Williston Basin, the DJ Basin, and the Permian Basin.
The turning point came in November 2014 when oil prices fell rapidly. As prices bottomed out at $22/bbl in February 2015, the industry saw a large exodus of operators and capital from the gas rich plays around the US to the liquid rich Permian. The Permian proved to be the haven for oil and gas development with its multiple pay zone targets, high EURs, low break-even costs, friendly regulatory environment, and access to markets. The rush for land, once again ensued, with the hope of an oil price rebound and promise of high returns to capital investors.
The rapid ramp up in activity from 2015–2018 did not come without challenges as it put strain on the availability of services and people, access to pipelines and markets, and access to frac sand/water. This drove up costs and resulted in mixed results for many companies. In addition, operators soon saw that with higher-than-expected gas and water production, expenses to manage these by-products sky-rocketed. Water handling and disposal became a huge portion of operating expenses and with gas export facilities at full capacity, companies started to flare gas in large volumes. Associated gas became a waste product, causing operators needed remove the gas and associated liquids from the revenue stream, and in some cases pay a high cost for flaring permits, rather than shutting in wells.
By 2019, a shift in the investment community was well underway. The days of growth-focused investment were coming to an end, and investors wanted to see returns on their investments. As prices still hovered around the $55/bbl range, investors were getting anxious to recover their capital invested in the industry, and throughout 2019 operators all talked about the ability to generate free cash flow. This paper analyses the free cash flow for three key unconventional basins across the US and discusses the associated economic impacts in each basin.
Rosenhagen, Nicolas M. (Colorado School of Mines) | Nash, Steven D. (Anadarko Petroleum Corporation) | Dobbs, Walter C. (Anadarko Petroleum Corporation) | Tanner, Kevin V. (Anadarko Petroleum Corporation)
Abstract The volume of stimulation fluid injected during hydraulic fracturing is a key performance driver in the horizontal development of the Niobrara formation in the Denver-Julesburg (DJ) Basin, Colorado. Oil production per well generally increases with stimulation fluid volume. Often, operators normalize both production and fluid volume based on stimulated lateral length and investigate relationships using "per-ft" variables. However, data from well-based approaches commonly display such wide distributions that no useful relationships can be inferred. To improve data correlations, multivariate analysis normalizes for parameters such as thermal maturity, depth, depletion, proppant intensity, drawdown, geology and completion design. Although advancements in computing power have decreased cycle times for multivariate analysis, preparing a clean dataset for thousands of wells remains challenging. A proposed analytical method using publicly available data allows interpreters to see through the noise and find informative correlations. Using a data set of over 5000 wells, we aggregate cumulative oil production and stimulation fluid volumes to a per-section basis then normalize by hydrocarbon pore volume (HCPV) per section. Dimensionless section-level Cumulative Oil versus Stimulation Fluid Plots ("Normalization" or "N-Plot") present data distributions sufficiently well-defined to provide an interpretation and design basis of well spacing and stimulation fluid volumes for multi-well development. When coupled with geologic characterization, the trends guide further refinement of development optimization and well performance predictions. Two example applications using the N-Plot are introduced. The first involves construction of predictive production models and associated evaluation of alternative development scenarios with different combinations of well spacing and completion fluid intensity. The second involves "just-in-time" modification of fluid intensity for drilled but uncompleted wells (DUC's) to optimize cost-forward project economics in an evolving commodity price environment.
CNOOC’s “Major Find” In North Sea Is Biggest In 11 Years
Trent Jacobs, JPT Digital Editor
The Chinese National Offshore Oil Corporation (CNOOC) discovered a gas and condensate reservoir at the state-owned company’s Glengorm prospect in the UK North Sea. The resource, located 118 miles east of Aberdeen, is estimated to hold close to 250 million bbl BOE.
CNOOC tapped the reservoir in a water depth of 282 ft with a jackup rig. Total depth of the exploration well was just over 16,500 ft and gas and condensate pay zones were found with a thickness of 123 ft. The company had previously tried and failed to drill two prospect wells in 2017.
Xie Yuhong, executive vice president of CNOOC, said the “Glengorm discovery demonstrates the great exploration potential” for the offshore block and that the company is “looking forward to further appraisal.” CNOOC is the operator of the field with a 50% interest. French supermajor Total owns a 25% stake in the field and Euroil holds the remaining 25%.
Chesapeake Teams with Analytics Firm to Improve Asset Performance
Matt Zborowski, Technology Writer
Chesapeake Energy is partnering with RS Energy Group to improve operational efficiency and capital discipline by employing advanced analytics and machine learning.
RS Energy is a Calgary-based energy research firm founded in 1998 covering more than 150 operators in the major North American and international oil and gas regions, including the US shale plays. It provides technical analysis of basins, including completions and production, as well as asset evaluations for operators considering acreage additions. All of this is done within the context of shifting capital markets.
Chesapeake announced the pact fresh off its $4-billion merger with WildHorse Resource Development, which bolstered its position in the Eagle Ford Shale of South Texas. The Oklahoma City-based independent has overhauled its portfolio in recent years and now is focused on just a few major US basins, increasing its companywide share of oil production, and reducing debt.
Noble Energy Touts Output Gains, Potential from “Row Development” Concept
Matt Zborowski, Technology Writer
“Row development” is in full swing on Noble Energy’s operated acreage in Colorado’s DJ Basin, and now the company is beginning to apply the approach to its Delaware Basin acreage in West Texas.
The first completed row in Noble’s 75,000-acre Mustang project in the DJ Basin produced 26,000 BOE/D, of which 60% was oil, during fourth quarter 2018, the independent reported in its year-end earnings call. The row consists of 31 wells.
“We expect that momentum to continue into 2019,” said Brent Smolik, Noble president and chief operating officer. Bolstered in part by row development, the firm’s overall DJ oil and gas output increased 10% during the quarter and 15% for the year.
EIA Adds New Plays to Shale Gas, Tight Oil Reports
Stephen Whitfield, Senior Staff Writer
The US Energy Information Administration (EIA) has added new play production data to its shale gas and tight oil reports. Last December, US shale and tight plays produced approximately 65 Bcf/D of natural gas and 7 million B/D of crude oil, accounting for 70% and 60% of US production in those areas, respectively. These totals represent a significant jump in the last 10 years: shale gas and tight oil accounted for 16% of total US gas production and approximately 12% of US total crude oil production, according to EIA statistics.
EIA updated its production volume estimates to include seven additional shale gas and tight oil plays, increasing the share of shale gas by 9% and tight oil by 8% compared with previously estimated shale production volumes. The change captures increasing production from new, emerging plays as well as from older plays that had previously been in decline, but are now rebounding because of advancements in horizontal drilling and hydraulic fracturing.
Devon Pulls Up Its Roots, Goes All In on US Oil
Stephen Rassenfoss, JPT Emerging Technology Senior Editor
Devon Energy will be shedding its holdings in the Barnett and the Canadian oil sands as part of a program to shrink the company to focus on four US unconventional oil plays.
The program announced along with earnings is the last step in a series of asset sales to create a “New Devon,” which also promises to reduce annual costs by $780 million by 2021, with most of that done by the end of this year.
The “sustainable cost reductions” will target expenses in field operations, drilling, and completions. It did not specifically mention job reductions, but the list of cost-saving steps includes “better aligning personnel with the go-forward business.”
Brazil’s Lula Field a Step Closer to Producing 1 Million B/D
Petrobras, alongside partners Shell and Galp, has launched production from the seventh Lula field floating production, storage, and offloading (FPSO) vessel, bringing the consortium a step closer to reaching 1 million B/D of oil from the prolific Lula hub offshore Brazil.
Hydrocarbons are flowing to the P-67 FPSO as part of the Lula North deepwater project in the pre-salt Santos Basin. The vessel, which has a capacity of 150,000 B/D of oil and 6 million cu m/day of natural gas, sits in 2130 m of water on the BM-S-11 concession 260 km off Rio de Janeiro state.
P-67 will be connected to nine production wells and multiple injection wells. Oil will be offloaded to lifting vessels and gas will be sent through pre-salt gas pipelines.
Years in the making, the recent steady rise in drilling in the Powder River Basin of northeast Wyoming is generating excitement reminiscent of the early days of currently more-established US onshore oil plays.
The upturn in activity is resulting in double-digit production growth. Wells are bubbling over with oil, and operators are bubbling over with enthusiasm. This has been most evident in recent industry presentations, where decision makers from the basin’s exclusive club of operators have gushed over what is becoming a core asset in their portfolios.
Given the basin’s oil richness, multiple stacked horizons, and well performance and economics, “we think it’s comparable and competitive with the big-name basins—whether it’s the Permian, SCOOP, or STACK,” Joseph DeDominic, president and chief operating officer of Anschutz Exploration, said at a recent SPE Gulf Coast Section meeting on the basin.
“This is what really gets us excited—the fact that you have 5,000 ft of stacked pay which is very similar to what you see in the other basins,” generating a high-dollar amount per acre, said Aaron Ketter, vice president of Devon’s Rockies business unit, during the same event. Formations are “highly economical” at $50/bbl and under, he said, with the heart of the Turner zone sometimes breaking even in the high $30s/bbl.
Traditionally known for its prolific coal production, the Powder River Basin’s potential for oil became a stronger point of focus in the industry about a decade ago. Operators began moving in on the region, rigs in tow, collecting limited but valuable data on its formations. When the commodity price downturn struck the industry during 2014–2016, operators pulled back investment, resulting in the basin’s failure to launch.
In its current state as an oil play, the basin is still underdeveloped. While lots of vertical wells have been drilled there in the past, “the truth is, when you look at horizontal development, and even using modern completions, it’s really brand new. We’re just getting started,” said Joseph A. Mills, Samson Resources II president and chief executive officer. “Delineation is what’s happening today and that’s probably what’s going to go on for another couple of years.”
Companies that are now ahead of the curve arrived early in the basin, secured operatorships, began drilling years ago, held onto their acreage—and its accompanying data—through the downturn, and patiently waited for oil prices to rise and costs to fall.
“What’s unique about the Powder is just the areal extent of some of these zones aren’t the same magnitude as you see in the Permian or the Midcontinent. So zip code really matters,” said Ketter.
Current Lay of the LandDevon, Anschutz, and EOG Resources have the largest positions in the Powder River at around 400,000 net acres each. Chesapeake Energy and Anadarko Petroleum each has around 300,000 net acres, with the latter firm having just spent some $100 million to expand its position.
Abstract Unconventional completions in North America have seen a paradigm shift in volumes of proppant pumped since 2014. There is a clear noticeable trend in both oil prices and proppant volumes – thanks to low product and service costs that accompanied the oil price crash in early 2015. As the industry continues to recover, operators are reevaluating completion designs to understand if these proppant volumes are beyond what is optimal. This paper analyzes trends in completion sizes and types across all major unconventional oil and gas plays in the US since 2011 and tracks their impact on well productivity. Completion and production data since 2011 from more than 70,000 horizontal wells in seven major basins (Gulf Coast, Permian, Appalachian, Anadarko, Haynesville, Williston and Denver Julesburg basins) and 11 major oil/gas producing formations were analyzed to examine developments in proppant and fluid volumes. Average concentration of proppant per gallon of fluid pumped was used to understand transitional trends in fracturing fluid types with time. Production performance indicators such as First month, Best 3 or Best 12 months of oil and gas production were mapped against completion volumes to evaluate if there are added economic advantages to pumping larger designs. In general, all major basins have seen progressive improvements in average well performance since 2011, with the Permian Basin showing the highest improvement, increasing from an average first-six-months oil production of 25,000 bbl in 2011 to 75,000 bbl in 2017. The Gulf Coast basin, where the Eagle Ford formation is located, has seen a 6-fold increase in proppant volumes pumped per foot of lateral since 2011 while the Permian and Appalachian basins hit peak proppant volumes in 2015 and 2016 respectively. In Permian and Eagleford wells, higher proppant volumes in general have resulted in better production up to a certain concentration. In Williston and Denver basins, most operators are moving away from gelled fluids, and reduced average proppant concentration per fluid volume pumped shows inclination toward hybrid or slickwater designs. While some of these observations are tied to reservoir quality, proppant volumes have begun to peak as operators have either reached an optimal point or are in the process of reducing volumes. Demand for proppant is expected to nearly double by 2020. As oil prices continue to recover, well AFEs continue to increase, despite multiple efforts to improve capital efficiency. The need for enhanced fracture conductivity and extended half-lengths on EURs are been discussed by combining actual observed production data and sensitivities using calibrated production models. The industry is moving toward large-volume slickwater fracturing operations using smaller proppants, but he operating landscape is expected to see a correction when such designs become less economical.