Kern River Research Articles

Fluvial reservoir architecture, directional heterogeneity and continuity, recognizing incised valley fills, and the case for nodal avulsion on a distributive fluvial system: Kern River field, California

Fluvial reservoir architecture, directional heterogeneity and continuity, recognizing incised valley fills, and the case for nodal avulsion on a distributive fluvial system: Kern River field, California

The Sierra Nevada (California) Is a Relict Tropical Late Cretaceous Range: A Field Guide to the Evidence

ABSTRACT: The notion of late-Cenozoic uplift was implied in 1865 by Whitney, who assumed a buried bedrock canyon lay beneath the Table Mountain latite flow and above the modern Stanislaus River canyon, with the difference between the two longitudinal profiles suggesting post-latite uplift. However, only a series of buried bedrock ridges exists and no uplift is inferred. I briefly present thirty-three key sites of about three hundred remnants in the entire Sierra Nevada, from north of the Feather River south to the Kern River. These include Late Cretaceous strata, Eocene strata, Oligocene rhyolites, Mio-Pliocene andesites, and Quaternary basalts, some remnants on canyon floors but most on lower slopes, preserving topography at the time of deposition. I found no evidence of late-Cenozoic incision, which is required under the late-Cenozoic uplift paradigm. Instead, each site contains verifiable field evidence that challenges the uplift paradigm. Moreover, the results are consistent with the range having a common uplift history: the crest elevation, drainage topography, and relief developed in the Late Cretaceous, and only minor changes occurred in post-Eocene time. This supports uplift studies in the northern Sierra based on hydrogen and oxygen isotopes on auriferous deposits, and supports pediment ages of 40+ Ma in the southern Sierra. Uplift studies based on thermochronology and numerical modeling, on cave-sediment dating and its implied incision, and on significant denudation on benchlands cannot be reconciled with verifiable field evidence. Finally, migration of giant sequoias southwest into the Sierra Nevada was possible only from late in the Cretaceous, when the Nevadaplano came into existence and the range was high, negating any Sierran late-Cenozoic uplift paradigm.

Airborne Trace Gas Remote Sensing and Surface Mobile In Situ: A Novel Tool for the Study of Structural Geological Controls from a Producing Oil Field

SummaryAccurate and representative determination of greenhouse gases (GHG) from oil and gas (O&G) production facilities requires high-spatial-resolution data, which can be acquired by airborne imaging spectrometers. However, assessment of nonmethane hydrocarbon emissions, which are far less amenable to remote sensing, requires mobile surface in-situ measurements (e.g., a mobile air quality laboratory).Field in-situ measurements and airborne thermal infrared spectral imagery were acquired for three producing California oil fields (Poso Creek, Kern Front, and Kern River) located next to each other on 14 September 2018. In addition, a profile ascending a nearby mountain collected in-situ data for the Round Mountain oilfield. Plume methane to ethane ratios were consistent within different regions of the field and differed between these fields in a manner related to field geological structures.Data acquired by an airborne thermal infrared imaging spectrometer, Mako, in 2015 and 2018 showed most emissions were from distant plumes in the Kern Front and Poso Creek fields. The spatial distribution of detected plumes was strongly related to faults, particularly active faults, which are proposed to stress infrastructure, leading to higher fugitive emissions and/or emissions from natural migration pathways (seepage). Additionally, the spatial distribution of detected plumes suggested unmapped faults. Thus, high-sensitivity imaging spectroscopy can improve understanding of reservoir geological structures that impact hydrocarbon migration and field operations, highlighting the potential for a novel reservoir management tool.

Full vs. Empty

Full vs. Empty

Using mobile surface in situ and remote sensing and airborne remote sensing to derive emissions from a producing central California oil field in complex terrain

In this study, we demonstrate how under certain wind conditions, a mobile surface in situ platform, Truck MObile trace Gas (TMOG) Surveyor, that includes a ceilometer to derive boundary layer height (BL) can derive emissions. Field in situ and airborne thermal infrared imaging spectroscopy data were acquired by the thermal infrared imaging spectrometer, Mako, for three adjacent, central California producing oil fields (Kern River, Kern Front, Poso Creek) on 14 Sept. 2018. Derived methane (CH4) and carbon dioxide (CO2) emissions from TMOG data were 46.6 ± 15 Mg dy−1 (17 ± 5.6 Gg yr−1) and 3.12 ± 1.02 Mg dy−1 (1140 ± 230 Gg yr−1), respectively, with about half the CH4 from near-field point-source plumes and half from a well-mixed far field plume. Uncertainty was 33 % from the Monte Carlo simulations. Mako data confirmed that emissions were in the far field and there were no strong, buoyant plumes. The survey vertically profiled a nearby mountain to measure winds at the boundary layer top and validate BL using in situ data.The CH4 to CO2 emissions ratio for plume matched reservoir composition to better than 10 %. The plume anomaly CH4 to ethane emissions ratio suggested ethane emissions of around 200 kg dy−1 (74 Mg yr−1). Mako data in 2015 and concurrent data in 2018 confirmed that most emissions were from distant plumes in the Poso Creek and Kern Front fields.

Early successional riparian vegetation is important for western Yellow‐billed Cuckoo nesting habitat

Western Yellow‐billed Cuckoo (Cuckoo; Coccyzus americanus) populations continue to decline in the western United States despite efforts to increase availability of riparian forest. Cuckoos have unique breeding habitat requirements such as large contiguous tracts of riparian forest (>80 ha), large estimated home ranges (20–90 ha), and dense vertical structure around the nest. However, local habitat‐scale features may be missing in landscapes of predominantly mature riparian forest that may need to be specifically managed for nesting. We used historical nest data (n = 95) from the South Fork Kern River Valley, California, from 1985 to 1996 to identify important nest site features that may be missing in current riparian forests. We found that increased canopy cover and vertical structure at all levels in the canopy greatly increased the probability of Cuckoo nesting. With smaller estimated effect sizes, the probability of Cuckoo nesting increased with increasing willows and forbs and smaller mean tree dbh. Cuckoos selected plots with disproportionately high percent willow cover relative to availability plots regardless of whether sites had low or high percent willow available. Counts of fledged young were positively related to willow percentage. No vegetation variable influenced daily survival rate which was 0.991 (LCI = 0.980, UCI = 0.996). Overall 17‐day nest success was likely high (0.86, LCI = 0.71, UCI = 0.93). In the absence of natural processes that create early successional stage forest, specific management for early successional stage forest is needed to increase the probability of Cuckoo nesting and nest productivity.

Groundwater Recharge for a Regional Water Bank

The Kern Water Bank is a semi-private groundwater bank operated by the Kern Water Bank Authority in Kern County, CA. The bank stores water from the State Water Project (SWP), Central Valley Project (CVP), and the Kern River. It is massive in scale, covering over 20,000 acres, with approximately 2.5 million acre feet diverted to the bank since 1995. The bank stores water on behalf of its member water agencies, which include both public and private water entities mainly focusing on agricultural use, along with a small number of municipal and residential customers. Water is withdrawn by the member agencies during droughts when surface water supplies from the SWP, CVP, and Kern River are insufficient to meet local demand or when member agencies elect to sell their stored water to outside third parties. In addition, the overlying land and infiltration ponds serve as habitat for some endangered and threatened species. Legal and political controversy surrounded the bank’s creation, but its unique suite of physical assets, creative enabling agreements, and clear operational rules and incentives have enabled it to use managed aquifer recharge to make significant contributions to the flexibility of regional and statewide water systems over decades of operations.

Challenging our understanding of western Yellow‐billed Cuckoo habitat needs and accepted management practices

Riparian restoration in the southwestern United States frequently involves planting cottonwood (Populus spp.) and willow (Salix spp.). In the absence of flooding and gap‐forming disturbance, planted forests often senesce without further young tree recruitment. This has largely been the case in California riparian systems that historically supported state‐endangered western Yellow‐billed Cuckoo (Coccyzus americanus; Cuckoo). A decline in Cuckoo population numbers in the past 30 years has been associated with forest maturation. Other riparian species of concern show a concomitant decline, indicating the problem is not specific to Cuckoos. Although varying hypotheses exist for recent decline, alternative management practices have not been sufficiently explored to rule out breeding ground habitat quality as a major contributing factor. Few intensive Cuckoo datasets exist to test hypotheses about breeding habitat quality due to extremely low populations in the remaining occupied sites. We used a historical (1986–1996) spot mapping dataset from the South Fork Kern River Valley, CA to identify vegetation characteristics related to Cuckoo and five other sensitive riparian bird territory densities. We found Cuckoo densities were positively associated with increased vertical vegetative structure 1–5 m above ground with a threshold for mean tree height. Sensitive species densities were also related to vertical structure and started to decline with stand height greater than 6–8 m. Naturally regenerated sites had higher densities of most sensitive bird species than planted sites. We provide ideas for restoring mature forest with little vertical structure.

Flow Profiling Using Fiber Optics in a Horizontal Steam Injector with Liner-Deployed Flow Control Devices

SummaryHorizontal steam injectors can improve the efficiency of thermal operations relative to vertical injectors. However, effective in-well and reservoir surveillance are needed to understand steam conformance. Uniform steam-chest development improves the steam/oil ratio in continuous steam injection and accelerates recovery in cyclic steam injection. The conformance of the injected steam can be achieved by flow control devices (FCDs) deployed on either tubing or liner. A new liner-deployed FCD was used in a horizontal steam injector in the Kern River field. The liner-deployed FCD is intended to replace the tubing-deployed FCDs while reducing capital costs, surveillance costs, and well intervention costs for conformance control.Fiber optics was used for surveillance, which is the most promising method in horizontal steam injectors considering reliability, accuracy, and cost. Fiber optic data enables monitoring the performance of liner-deployed FCDs as well as estimating the flow profile along the lateral length. Multimode distributed temperature sensing (DTS) optical fibers and single-mode distributed acoustic sensing (DAS) optical fibers were installed in the well for these objectives. Algorithms for interpreting DTS were improved to include a new technique, shape language modeling (SLM), and a probabilistic approach. The configuration of the FCDs was changed during the first well intervention, and it was monitored by DTS and DAS. Data from both DTS and DAS confirms the open/closed position of the sliding sleeve of FCDs initially and after the intervention. The probabilistic estimates of steam outflow in several FCD configurations match well with the theoretical outflow that is expected from the critical flow of steam through chokes installed in the FCDs.

Fluvial architecture and four-dimensional saturation modeling of a steam flood: Kern River field, California

The upper Miocene Kern River Formation at Kern River field is a thick succession of braided stream deposits. Because the oil field has been penetrated by more than 21,000 wells, with well spacing typically of 2.5 ac (104 m2), high-quality imaging of the reservoir can be accomplished using well logs. The field contains more than 650 observation wells recording temperatures and saturation, such that heating and drainage of the reservoir can be characterized over time. Oil and gas saturations in a 360-ac (1.5 × 106-m2) study area within the Kern River field were modeled in three dimensions over time, creating a four-dimensional (4-D) earth model. Static lithology and porosity properties were first created. Then, temperature, oil, and gas saturations were kriged using data from observation wells at different time increments. From these kriged models, difference models were created to show changes in oil and gas saturation with time. Changes in oil volumes in the 4-D model matched produced volumes within a 10% error. Next, categorical descriptions of net oil saturation were made (best oil, background oil, partially drained, and residual saturations), and temporal evolution of the volumes of the different categories was modeled. By characterizing the reservoir in detail using the well-log data to define a reservoir framework and the observation wells to characterize changes over time, significant challenges in steam-flood reservoir management can be addressed, including determining which parts of the reservoir are producing the most and recognizing parts of the reservoir that are not actively draining.

Groundwater quality of a public supply aquifer in proximity to oil development, Fruitvale oil field, Bakersfield, California

Due to concerns over the effects of oil production activities on groundwater quality in California, chemical, isotopic, dissolved gas and age-dating tracers were analyzed in samples collected from public-supply wells and produced-water sites in the Fruitvale oil field (FVOF). A combination of newly collected and historical data was used to determine whether oil formation fluids have mixed with groundwater used for public supply and what the potential pathways for the migration of oil formation fluids into groundwater may be. Stable isotopes of water (δ2H and δ18O) and age dating (3H, 3Hetrit, SF6 and 14C) tracers in groundwater samples were consistent with the Kern River being the main source of recharge to aquifers. The distribution of major ion concentrations and pH with distance from the Kern River indicate that natural processes were the primary controls on groundwater salinity. Two of 14 groundwater samples had δ13C-DIC values (−2.4 to +1.9 per mil) consistent with mixtures of <1 to about 9 percent oil-field water. Concentrations of TDS in groundwater samples were generally much lower (129–1,200 milligrams per liter (mg/l), median 216 mg/l) than produced water samples (586–24,930 mg/l, median 2,717 mg/l), suggesting that any mixing of oil-field water with groundwater has not significantly affected groundwater salinity. Trace concentrations of thermogenic methane were detected in three groundwater samples that did not have dissolved inorganic or isotopic indicators consistent with mixing of oil-field water, suggesting that stray gases may have migrated from the subsurface via preferential pathways such as leaky well bores into groundwater aquifers. Low concentrations of petroleum hydrocarbons were detected in samples that also contained anthropogenic VOCs and components of post- and pre-1950s recharge, indicating that petroleum hydrocarbons could have come from subsurface and/or surface sources. Overall, the results of this study indicated that groundwater currently used for public supply in the FVOF was of good quality with little, if any, effects from oil production activities. This may be due in part to the relatively rapid flushing of the aquifer system by recharge from the Kern River.

Core-periphery dynamics in the Kern River watershed

This study generates a comprehensive database of archaeological resources to evaluate Late Prehistoric (c 1500-150 cal BP) settlement and land use behaviours in the Kern River watershed of the far southern Sierra Nevada, California. These behaviours are evaluated using a habitat suitability model that relates the spatial distribution of critical subsistence resources present within the study area to suitability. Determining the habitat distribution operating in the Kern River watershed during the Late Prehistoric period is difficult using the model developed here. Settlement and land use behaviours trend towards a free distribution when evaluating all archaeological data associated with the Late Prehistoric period, but the results trend towards a despotic distribution when only incorporating lower elevation sites typically associated with more intensive residential activities. While it is difficult to identify these patterns using the model developed here, it is possible to identify several preferred areas within the study area. Preferred areas in the Kern River watershed are generally located in ecotonal habitats which contain less access to staple resources than peripheral habitats reflecting traditional Californian or Great Basin ecosystems. A settlement and land use strategy focused on ecotonal habitats at the core of the territory promotes territorial maintenance in several ways including creating a physical and social buffer against potential competitors, maintaining access to two staple resource bases and promoting long-term territorial stability among numerous ethnolinguistic populations. These results have implications for our understanding of the range of territorial behaviours practised by foraging groups, particularly low population density groups like the Tubatulabal.

Horizontal Steam Injectors in the Kern River Field

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 187258, “Design and Operational Experience With Horizontal Steam Injectors in the Kern River Field, California, USA,” by R.S. Buell, SPE, R. Gurton, J. Sims, SPE, M. Wells, G.P. Adnyana, M. Shirdel, SPE, C. Muharam, T. Gorham, SPE, E. Riege, and G.B. Dulac, Chevron, prepared for the 2017 SPE Annual Technical Conference and Exhibition, San Antonio, Texas, USA, 9–11 October. The paper has not been peer reviewed. A horizontal-steam-injection pilot project has been under way for the last 4 years in the Kern River heavy-oil field in the southern San Joaquin Valley of California. This project was designed to address a series of learning objectives for horizontal steam injection in a mobile heavy-oil reservoir. These objectives included mechanical integrity and operability, steam conformance control, steam-flow profiling, and reservoir response and long-term operability. Introduction While documented cases of continuous and cyclic horizontal steam injection in mobile heavy oil exist, these have not led to large-scale economic development of thermal heavy oil. Most thermal, mobile, heavy oil is currently produced with vertical steam injectors. The Kern River Field is a good example of this recovery technique. The primary heavy-oil reservoir in the field is 300 to 1,300 ft deep, with a reservoir thickness of up to 900 ft. During the last 50 years, most of the field has been developed with continuous vertical steam injectors, with typical pattern spacing being 2.5 acres. The pilot area is approximately 12 acres and is on the northwest flank of the field. The pilot injected steam into sand that has an average thickness of 22 ft across the pilot area. The pilot’s original configuration included two horizontal injectors, nine vertical producers, and 12 temperature-observation wells (TOWs). Of the 23 wells in the pilot area, five were existing wells and the remainder were new drills. Two types of TOW were used in the pilot: (1) injector TOWs, which have a short offset of less than 40 ft from the horizontal injectors and are intended to assist in understanding injector steam conformance, and (2) reservoir TOWs, which are more than 50 ft from injectors and producers and are intended to help understand far-field reservoir response. The pilot used horizontal continuous steam injection but is different from a bitumen steam-assisted-gravity-drainage application in that the heavy oil is mobile and will flow at reservoir conditions. Another important difference is that a horizontal producing well has not been placed 15 to 25 ft under the horizontal injector. In fact, vertical producing wells were used in the pilot area offset 140 ft from the horizontal injectors.

Geomorphic constraints on the incision history of the lower Kern River, southern Sierra Nevada, California

Geomorphic constraints on the incision history of the lower Kern River, southern Sierra Nevada, California

Quaternary basaltic volcanism in the Golden Trout Volcanic Field, southern Sierra Nevada, California

The Golden Trout Volcanic Field (GTVF) produced the only Quaternary eruptions of mafic magma within the southern Sierra Nevada block. Approximately 38×106m3 of basalt, trachy-basalt, basaltic trachy-andesite, and basaltic andesite (50.1–56.1% SiO2, 1.1–1.9% K2O, and 5.4–9.1% MgO) was erupted from four vents within a ~10km2 portion of the GTVF, which also includes rhyolite domes that are not considered in this study. The vents include, from oldest to youngest: Little Whitney Cone, South Fork Cone, Tunnel Cone, and unglaciated Groundhog Cone. Little Whitney Cone is a 120m-high pile of olivine-CPX-phyric scoria produced during a Strombolian-style eruption overlying two columnar jointed lava flows. Tunnel Cone formed through a Hawaiian-style eruption along a 400m-long north-south trending fissure that excavated at least three 25–65m-wide craters. Crater walls up to 12m high are composed of plagioclase-olivine-phyric spatter-fed flows that dip radially away from the crater center and crumble to form Tunnel Cone's steep unconsolidated flanks. South Fork Cone is a 170m-high pile of plagioclase-olivine-phyric scoria that formed during Strombolian to violent Strombolian eruptions. South Fork Cone overlies the South Fork Cone lava, a 9.5km-long flow (~12×106km3) that reached the Kern River Canyon to the west. Scoria and airfall deposits originating from South Fork Cone are located up to 2km from the vent. Groundhog Cone is a 140m-tall cinder and spatter cone breached on the north flank by a 13×106m3 lava flow that partially buried the South Fork Cone lava and extends 7.5km west to Kern River Canyon. Incompatible trace element concentrations and ratios show vent-specific trends but are unsystematic when plotted in terms of all mafic GTVF vents, implying that GTVF basalts were derived from a lithospheric mantle source and ascended through thick granitic Sierra Nevada crust as discrete batches that underwent different degrees of crustal contamination, differentiation, and magma mixing. Clinopyroxene-liquid thermobarometry calculations of the oldest and most primitive GTVF sample indicate that most clinopyroxene crystals record nucleation conditions of 1172–1196°C and 896–1115MPa. These pressures correspond to depths equivalent to, or up to 10km shallower than, the Moho in this region. Deposits from the oldest GTVF vents are more primitive and homogeneous in terms of major and trace element concentrations, phenocryst textures and compositions, and their general absence of crustal xenoliths and xenocrysts compared to younger eruptive products. The eruption rate of the GTVF (~0.05km3/Myr) is two orders of magnitude less than neighboring and contemporaneous Big Pine and Coso volcanic fields to the north and east, respectively. We interpret these differences to result from a relative lack of strain in the GTVF region of the southern Sierra Nevada block, which limits magma accumulation and ascent.

Review of Renewable Energy Technologies Utilized in the Oil and Gas Industry

In this study, applications of renewable energy technologies in the oil and gas industry were analyzed. A number of photovoltaic systems were investigated as applications for providing electric power to production facilities (i.e. the oil fields of Midway-Sunset, Kern River and Louisiana Bayou in the United States). Wind power systems were studied in the oil fields of Suizhong 36-1 (China), Beatrice (UK) and Utsira Nord (Norway). The geothermal power systems studied included the oil fields of Rocky Mountain (USA) and Fort Liard (Canada). Moreover, solar thermal systems in the oil fields of Mckittrick (USA), Caolinga (USA) and Amal (Oman) were examined as applications for providing thermal energy to production facilities. From the results, this study revealed that a variety of renewable energy technologies are currently used in the oil and gas industry. In particular, solar thermal systems are being actively studied for provision of the thermal energy required to enhance oil recovery.

Sediment provenance and dispersal of Neogene–Quaternary strata of the southeastern San Joaquin Basin and its transition into the southern Sierra Nevada, California

We have studied detrital-zircon U-Pb age spectra and conglomerate clast populations from Neogene–Quaternary siliciclastic and volcaniclastic strata of the southeastern San Joaquin Basin, as well as a fault-controlled Neogene basin that formed across the southernmost Sierra Nevada; we call this basin the Walker graben. The age spectra of the detrital-zircon populations are compared to a large basement zircon age data set that is organized into age populations based on major drainage basin geometry of the southern Sierra Nevada and adjacent ranges. We find a direct sediment provenance and dispersal link for much of the Neogene between the Walker graben and the southeastern San Joaquin Basin. In early to middle Miocene time, this link was accented by the delivery of volcaniclastic materials into the southeastern Basin margin from the Cache Peak volcanic center that was nested within the Walker graben. In late middle Miocene through early Pleistocene time, this linkage was maintained by a major fluvial system that we call the Caliente River, whose lower trunk was structurally controlled by growth faults along the Edison graben, which breached the western wall of the Walker graben. The Caliente River redistributed into the southeastern San Joaquin Basin much of the ∼2 km of volcaniclastic and siliciclastic strata that filled the Walker graben. This sediment redistribution was forced by a regional topographic gradient that developed in response to uplift along the eastern Sierra escarpment system. The Caliente River built a fluvial-deltaic fan system that prograded northwestward across the lower trunk of the Kern River and thereby deflected the Kern drainage flux of sediment into the Basin edge northward. In mainly late Miocene time, turbidites generated primarily off the Caliente River delta front built the Stevens submarine fan system of the southeastern and central areas of the San Joaquin Basin. In late Quaternary time, 1–1.8 km of Caliente River–built strata were eroded as an epeirogenic uplift that we call the Kern arch emerged along the southeastern Basin margin, in response to underlying mantle lithosphere removal. The sediment that was eroded off the arch was redistributed mainly into the Maricopa and Tulare sub-basins that are located to the southwest and northwest, respectively, of the arch.

Characterization of anthropogenic methane plumes with the Hyperspectral Thermal Emission Spectrometer (HyTES): a retrieval method and error analysis

Abstract. We introduce a retrieval algorithm to estimate lower tropospheric methane (CH4) concentrations from the surface to 1 km with uncertainty estimates using Hyperspectral Thermal Emission Spectrometer (HyTES) airborne radiance measurements. After resampling, retrievals have a spatial resolution of 6 × 6 m2. The total error from a single retrieval is approximately 20 %, with the uncertainties determined primarily by noise and spectral interferences from air temperature, surface emissivity, and atmospheric water vapor. We demonstrate retrievals for a HyTES flight line over storage tanks near Kern River Oil Field (KROF), Kern County, California, and find an extended plume structure in the set of observations with elevated methane concentrations (3.0 ± 0.6 to 6.0 ± 1.2 ppm), well above mean concentrations (1.8 ± 0.4 ppm) observed for this scene. With typically a 20 % estimated uncertainty, plume enhancements with more than 1 ppm are distinguishable from the background values with its uncertainty. HyTES retrievals are consistent with simultaneous airborne and ground-based in situ CH4 mole fraction measurements within the reported accuracy of approximately 0.2 ppm (or ∼ 8 %), due to retrieval interferences related to air temperature, emissivity, and H2O.

Modeling the trust-risk relationship in a wildland recreation setting: A social exchange perspective

We empirically tested relationships among the characteristics of trustworthiness, trust instilled in river guides, and risks perceived by whitewater recreationists that rafted a Wild and Scenic River in the Southern Sierra Nevada, CA. Drawing on a social exchange framework, we used survey data to address the following objectives: 1) investigate three dimensions of trustworthiness, including ability, integrity, and benevolence; 2) examine trust in decisions and trust in values that recreationists associated with their river guides; and 3) determine the effects of trustworthiness and trust on recreationists' beliefs that river guides minimized psychological and social risks from rafting the Kern River. Results from a latent variable path model revealed that the ability and integrity of river guides played important roles in explaining why they were trusted by recreationists, which in turn positively influenced the extent to which guides were believed to minimize risk. Contrary to previous research, we found that trust in values did not play a substantive role in predicting risk perception. A greater understanding of the trust-risk relationship will shed light on how public land management agencies can effectively navigate risk in dangerous wildland environments and provide access to otherwise inaccessible resources owned and valued by the public. Management ImplicationsOur results offer insight on how public land management agencies can negotiate risk and maintain high quality recreational opportunities afforded by wildland environments. Specifically, our study findings suggest:●Whitewater recreationists may not be able to access and/or enjoy wildland environments without trust and trustworthiness garnered from the assistance of guides.●The trust-risk relationship can be understood from a social exchange perspective.●Trustworthiness is an important mechanism for explaining trust in decisions and trust in values.●The extent to which river guides are thought to minimize risks can be predicted by the ability and integrity of a river guide and trust placed on their decisions.●The benevolence of river guides does not factor into the formation of trust or the risk perceptions of whitewater recreationists.

Technology Focus: Sand Management and Sand Control (October 2015)

Technology Focus Ours is a cyclical business. Those involved in well work (i.e., drilling, completions, and workovers) are currently feeling the effects of reduced activity. Overall, I think those involved with drilling activities are affected most. Those involved with completions and workovers are affected to a lesser degree simply because of the opportunity to optimize. Whether that optimization occurs as part of improvements to the completions processes or workover processes, similar skills are needed. For operators, the most cost-efficient barrel we produce is the next one that is produced after we optimize an already-producing well. It is the operator’s responsibility to find ways to optimize production. This is often achieved through interventions or recompletions. In challenging financial times (as with technical challenges), we need to be flexible enough to refocus our efforts in new and often uncomfortable ways. Each of the papers I have selected provides examples of how to do just that: challenge the status quo. Many of us have been so busy chasing the next well and the upcoming job that our skills in the area of optimizing our completions may have become a little rusty. Now is a great time to knock off that rust and revisit our best-laid plans. One way may be for you, alone or with your peers, to review the wells completed in your current project, or a subset of those wells, and figure out what went right and what went wrong. This deep dive into the details will often pay significant dividends in terms of understanding your current project. With that deeper understanding, you can develop an improvement plan for your current project or for your next project. The improvements required are often difficult to achieve. Operators, particularly those with inventory already on the ground and pressure to use that inventory, might not be comfortable with changing their approach. However, a significant change in direction might be exactly what is needed. In these challenging and uncomfortable times, I encourage each of you to challenge yourself and your peers to be uncomfortable and at least evaluate approaches that your organization might not have used historically. Those unfamiliar approaches might just be the right answer. The papers selected for this feature provide you, the reader, with the opportunity to learn from the efforts of others. I hope that you will be able to use one or more of their approaches to improve the economics in your assets. JPT Recommended additional reading at OnePetro: www.onepetro.org. SPE 170278 Successful Placement of an Advancing Sand- and Fines-Control Chemical as a Remedial Sand Control Using Subsea Flowlines From an FPSO by Michele Piemontese, Eni, et al. SPE 174240 Chemical Sand Consolidation as a Failed-Gravel-Pack Sand-Control Remediation in Handil Field, Indonesia by Antus Mahardhini, Total, et al. SPE 174407 A Successful Post- Completion Sand-Control Method Used in Thermal-Enhanced-Oil-Recovery Operations at the Kern River Field in Bakersfield, California by Spencer Franks, Chevron, et al.