James W. Castle

Chemical and physical characterization of produced waters from conventional and unconventional fossil fuel resources

Characterization of produced waters (PWs) is an initial step for determining potential beneficial uses such as irrigation and surface water discharge at some sites. A meta-analysis of characteristics of five PW sources [i.e. shale gas (SGPWs), conventional natural gas (NGPWs), conventional oil (OPWs), coal-bed methane (CBMPWs), tight gas sands (TGSPWs)] was conducted from peer-reviewed literature, government or industry documents, book chapters, internet sources, analytical records from industry, and analyses of PW samples. This meta-analysis assembled a large dataset to extract information of interest such as differences and similarities in constituent and constituent concentrations across these sources of PWs. The PW data analyzed were comprised of 377 coal-bed methane, 165 oilfield, 137 tight gas sand, 4000 natural gas, and 541 shale gas records. Majority of SGPWs, NGPWs, OPWs, and TGSPWs contain chloride concentrations ranging from saline (>30000 mg L(-1)) to hypersaline (>40000 mg L(-1)), while most CBMPWs were fresh (<5000 mg L(-1)). For inorganic constituents, most SGPW and NGPW iron concentrations exceeded the numeric criterion for irrigation and surface water discharge, while OPW and CBMPW iron concentrations were less than the criterion. Approximately one-fourth of the PW samples in this database are fresh and likely need minimal treatment for metal and metalloid constituents prior to use, while some PWs are brackish (5000-30000 mg Cl(-) L(-1)) to saline containing metals and metalloids that may require considerable treatment. Other PWs are hypersaline and produce a considerable waste stream from reverse osmosis; remediation of these waters may not be feasible. After renovation, fresh to saline PWs may be used for irrigation and replenishing surface waters.

Sedimentology and Fractal-Based Analysis of Permeability Data, John Henry Member, Straight Cliffs Formation (Upper Cretaceous), Utah, U.S.A.

Interpretation of depositional environments combined with field measurement of permeability for a portion of the Upper Cretaceous Straight Cliffs Formation near Escalante, Utah, provides new results for understanding and modeling facies-dependent perme- ability variations. Offshore, transition-lower shoreface, upper shore- face, and foreshore environments are interpreted for part of the John Henry Member on the basis of outcrop investigation. Using a newly designed drillhole minipermeameter probe, permeability was measured for two of the facies within this unit: lower-shoreface bioturbated sand- stone and upper-shoreface cross-bedded sandstone. Approximately 500 permeability measurements at a sample spacing of 15 cm were made along four vertical profiles and three horizontal transects o na6m 3 21 m outcrop. Permeability ranges from 41 to 1,675 millidarcies (md) in the bio- turbated sandstone facies, which is massive-bedded, moderately to well-sorted, and very fine- to fine-grained. In contrast, permeability ranges from 336 to 5,531 md in the moderately to moderately well sorted, fine- to medium-grained, cross-bedded sandstone facies. A high degree of variability in permeability of the cross-bedded facies is caused by small-scale variations in grain size and structure related to depositional processes. The geometric mean permeability in the bio- turbated sandstone is 253 md, compared with 1,395 md in the cross- bedded facies. While the facies-dependent differences in permeability (k) are ap- parent and related to depositional and biological processes, fractal- based statistical analysis of the horizontal ln( k) increments yields near- ly identical results for the bioturbated facies and the cross-bedded fa- cies, possibly suggesting an underlying statistical commonality in the formation of both facies. Increment distributions from both facies ap- pear similar with peaking around the mean. Ln(k) increments from the smaller vertical data set appear similar also, but with a variance approximately 3.7 times larger than the horizontal value. Variance scaling analyses of horizontal and vertical data both yield a Hurst co- efficient near 0.26, which is characteristic of negative spatial correla- tion of the increments. The methodology developed herein offers a po- tential high-resolution alternative to existing methods for understand- ing and characterizing subsurface properties.

Recognition of Facies, Bounding Surfaces, and Stratigraphic Patterns in Foreland-Ramp Successions: An Example from the Upper Devonian, Appalachian Basin, U.S.A.

ABSTRACT A detailed stratigraphic study of the Upper Devonian Lock Haven Formation in the Appalachian basin provides new interpretations applicable to understanding sedimentation and stratigraphic architecture in the foreland-ramp setting. The common occurrence of graded beds, hummocky cross stratification, and shell lags indicates that storm processes played an important role in deposition. Gradational-based, coarsening-upward shoreface sequences of interbedded sandstone and mudstone formed during gradual fall in relative sea level. In contrast, sharp-based regressive sequences consist of laminated sandstone facies overlying a submarine erosion surface that developed in response to more rapid fall in relative sea level. Transgressive sequences become finer grained upward from conglomerate lag, which was deposited on a basal transgressive surface, to heterolithic facies and mudstone facies. A combination of eustasy and tectonic subsidence of the foreland ramp produced changes of relative sea level. These fluctuations provided a means for transporting sand onto the ramp and for producing repetition of stratigraphic patterns in the Lock Haven Formation. The Upper Devonian clastic succession, which includes both the Lock Haven Formation and the Catskill Formation, represents northwestward progradation of shoreline to nonmarine environments as sediment supply to the foreland ramp exceeded the rate of formation of accommodation. Compared to passive-margin shelves, thick fine-grained successions such as the Lock Haven Formation are more likely to form in foreland basins, where tectonic subsidence provides a mechanism for creating accommodation. Sediment influx from uplifted areas and absence of a slope break on the foreland ramp results in a higher rate of fine-grained clastic sedimentation than occurs on shelves of passive margins.

Performance of a pilot-scale constructed wetland system for treating simulated ash basin water

A pilot-scale constructed wetland treatment system (CWTS) was designed and built to decrease the concentration and toxicity of constituents of concern in ash basin water from coal-burning power plants. The CWTS was designed to promote the following treatment processes for metals and metalloids: precipitation as non-bioavailable sulfides, co-precipitation with iron oxyhydroxides, and adsorption onto iron oxides. Concentrations of Zn, Cr, Hg, As, and Se in simulated ash basin water were reduced by the CWTS to less than USEPA-recommended water quality criteria. The removal efficiency (defined as the percent concentration decrease from influent to effluent) was dependent on the influent concentration of the constituent, while the extent of removal (defined as the concentration of a constituent of concern in the CWTS effluent) was independent of the influent concentration. Results from toxicity experiments illustrated that the CWTS eliminated influent toxicity with regard to survival and reduced influent toxicity with regard to reproduction. Reduction in potential for scale formation and biofouling was achieved through treatment of the simulated ash basin water by the pilot-scale CWTS.

Foreland-basin sequence response to collisional tectonism

As structural salients and recesses evolved from reentrants and promontories along the collisional continental margin associated with the Taconic orogeny, cross- strike structural features provided a mechanism for transferring zones of relative subsidence and uplift across the Appalachian foreland basin. The regional distribution of Lower Silurian clastic sequences reflects this tectonic influence. Thick, aggradational sequences formed in areas corresponding to salients in response to high rates of sediment supply and creation of sediment accommodation. As the rate of sediment supply exceeded the rate of accommodation added, shoreline progradation onto the distal foreland ramp produced upward-coarsening sequences. In areas of structural recesses, accommodation was created by erosion during sea-level fall and lowstand. Upward-fining sequences formed as the topographic lows were filled during subsequent sea-level rise. Results from this investigation indicate that predictable variations in foreland-basin deposition and in the resulting stratigraphic pattern occur along regional tectonic strike as well as in the dip direction. The thickness of foreland-ramp sequences is greater in areas of salients than in recesses, whereas the ratio of sandstone to total thickness is greater in the recesses. Aggradational sequences grading laterally into upward-coarsening progradational sequences of the distal ramp characterize areas of relative subsidence, which provides a mechanism for creating sediment accommodation. In contrast, deep erosion, common unconformities, and incised valley fills are present in areas corresponding to recesses, where the rate of eustatic fall commonly exceeds the subsidence rate. These along-strike stratigraphic variations in response to collisional tectonism should be considered in the interpretation of other foreland-basin successions.

A risk assessment approach to identifying constituents in oilfield produced water for treatment prior to beneficial use.

A risk assessment approach incorporating exposure pathways and calculated risk quotients was applied to identifying constituents requiring treatment prior to beneficial use of oilfield produced water (OPW). In this study, risk quotients are ratios of constituent concentrations in soil or water to guideline concentrations for no adverse effects to receptors. The risk assessment approach is illustrated by an example of an oilfield water produced from non-marine geologic strata of a rift basin in sub-Saharan Africa. The OPW studied has the following characteristics: 704-1370 mg L(-1) total dissolved solids (TDS), 45-48 mg L(-1) chloride, and 103.8 mg L(-1) oil and grease. Exposure pathways of constituents in OPW used for irrigation include: ingestion of plant tissue, ingestion and direct contact of irrigated soil by livestock, inhalation of aerosols or volatilized constituents, and ingestion of OPW directly by livestock. Applying risk quotient methods for constituents in soil and water, constituents of concern (COCs) identified for irrigation and livestock watering using the OPW studied include: iron (Fe), manganese (Mn), nickel (Ni), zinc (Zn), and oil and grease. Approximately 165,000 barrels d(-1) (26,233 m(3) d(-1)) of OPW from the study site are available for use. Identification of COCs and consideration of water quantity allows for development of reliable treatment design criteria to ensure effective and consistent treatment is achieved to meet guideline levels required for irrigation, livestock watering, or other uses. This study illustrates the utility of risk assessment for identifying the COCs in OPW for treatment, the level of treatment required, and viable options for use of the treated water.

Local and regional tectonic control on sedimentology and stratigraphy in a strike-slip basin: Miocene Temblor Formation of the Coalinga area, California, USA

Abstract Sedimentological study of the Lower to Middle Miocene Temblor Formation in the Coalinga area of the San Joaquin basin (California, USA) provides new results applicable to understanding patterns of sedimentation and stratigraphic architecture in strike-slip basins along tectonically active margins. Detailed investigation of surface outcrops on the Coalinga anticline is integrated with description of cores from an adjacent oil field. This approach yields information on lateral variability of facies as well as vertical sequences, which contributes to deciphering the facies geometry and stratigraphic pattern. Five facies tracts are identified in the Temblor Formation (in ascending order): incised valley, estuarine, tide- to wave-dominated shoreline, diatomite, and subtidal. The vertical succession of facies tracts represents overall relative rise in sea level punctuated by episodes of non-deposition and exposure. Sediment accommodation was produced initially by incision of topography into the underlying Kreyenhagen Shale during relative sea-level fall and lowstand. Incised valley and estuarine facies tracts were deposited during subsequent rise in sea level. As additional accommodation was created by tectonic subsidence, tide- to wave-dominated, diatomite, and subtidal facies tracts were deposited. Periods of relative sea-level fall produced depositional hiatuses, some of which are overlain by distinctive shell-lag beds. The Temblor Formation represents deposition in an area influenced by along-strike tectonic variability associated with transform motion between the Pacific and North American plates. Stratigraphic study suggests that subsidence and uplift related to the transform boundary played a key role in deposition of the formation. Stratigraphic variations reflect the combination of basinal subsidence caused by regional extension and local uplift related to plate movement along the San Andreas transform zone. It is likely that strata deposited along other transform boundaries record similar tectonic effects.

Treatment of oil and grease in produced water by a pilot-scale constructed wetland system using biogeochemical processes.

Constructed wetland treatment systems (CWTSs) can effectively remove many constituents that limit beneficial use of oilfield produced water. The objectives of this investigation were: (1) to assess the effect of mass loadings of oil and grease (O & G) on treatment performance in pilot-scale subsurface flow and free water surface CWTS series having sequential reducing and oxidizing cells, and (2) to evaluate effects on treatment performance of adding a pilot-scale oil-water separator. Increase in O & G mass loading from 5 to 20 mg min(-1) caused decreases in both dissolved oxygen concentration and sediment redox potential, which affected treatment performance. Biogeochemical pathways for removal of O & G, iron, and manganese operate under oxidizing conditions, and removal rate coefficients for these constituents decreased (0.905-0.514 d(-1) for O & G, 0.773-0.452 d(-1) for iron, and 0.970-0.518 d(-1) for manganese) because greater mass loading of O & G promoted reducing conditions. With increased mass loading, removal rate coefficients for nickel and zinc increased from 0.074 to 0.565 d(-1) and from 0.196 to 1.08 d(-1), respectively. Although the sequential reducing and oxidizing cells in the CWTS were very effective in treating the targeted constituents, an oil-water separator was added prior to wetland cells to enhance O & G removal at high inflow concentration (100 mg L(-1)). The oil-water separator removed approximately 50% of the O & G, and removal extents and efficiencies approximated those observed at 50 mg L(-1) inflow concentration during treatment without an oil-water separator.

Petrophysics of Lower Silurian sandstones and integration with the tectonic-stratigraphic framework, Appalachian basin, United States

Petrophysical properties were determined for six facies in Lower Silurian sandstones of the Appalachian basin: fluvial, estuarine, upper shoreface, lower shoreface, tidal channel, and tidal flat. Fluvial sandstones have the highest permeability for a given porosity and exhibit a wide range of porosity (2–18%) and permeability (0.002–450 md). With a transition-zone thickness of only 1–6 m (3–20 ft), fluvial sandstones with permeability greater than 5 md have irreducible water saturation (Siw) less than 20%, typical of many gas reservoirs. Upper shoreface sandstones exhibit good reservoir properties with high porosity (10–21%), high permeability (3–250 md), and low Siw (20%). Lower shoreface sandstones, which are finer grained, have lower porosity (4–12%), lower permeability (0.0007–4 md), thicker transition zones (6–180 m [20–600 ft]), and higher Siw. In the tidal-channel, tidal-flat, and estuarine facies, low porosity (average 6%), low permeability (average 0.02 md), and small pore throats result in large transition zones (30–200 m; 100–650 ft) and high water saturations.The most favorable reservoir petrophysical properties and the best estimated production from the Lower Silurian sandstones are associated with fluvial and upper shoreface facies of incised-valley fills, which we interpret to have formed predominantly in areas of structural recesses that evolved from promontories along a collisional margin during the Taconic orogeny. Although the total thickness of the sandstone may not be as great in these areas, reservoir quality is better than in adjacent structural salients, which is attributed to higher energy depositional processes and shallower maximum burial depth in the recesses than in the salients.

Key Aspects for Successful Design and Implementation of Passive Water Treatment Systems

Introduction Water treatment has been implemented for decades to treat water supplies as well as “wastewater” from a variety of sources. Noteworthy are successes treating challenging contaminated waters, including industrial sources, mining influenced waters, and oil and gas produced waters. Passive water treatment is a process of simultaneously or sequentially mitigating contaminants and/or acidity and physicochemical properties in a man-made system. This is achieved by capitalizing on biological, geochemical, and coupled biogeochemical reactions, followed by the physical removal and sequestration of constituents. In its truest form, a passive water treatment system (PWTS) does not require power or chemicals after construction and can be designed as a sustainable system lasting for decades or longer with minimal intervention or maintenance. For waters that contain constituents of concern that are not amenable to treatment by naturally occurring biological, physical, or chemical pathways (e.g. sodium, chl...