Texas Gulf Coast Basin Research Articles

Bioturbation changing porosity, permeability, and fracturability in chalk? Insights from an Upper Cretaceous chalk reservoir (Buda Formation, Texas, USA)

The continuous rise in hydrocarbon demand, the production decline in conventional oilfields, and the remarkable improvement in extraction methods have allowed the hydrocarbon industry and subsequently, geoscientists, to turn to studies on both unconventional and mature fields with untapped potential. In such reservoirs, the application of advanced drilling, completion, and production techniques must be preceded by the identification of permeable stratigraphic intervals that favour commercial exploitation. Accordingly, bioturbated deposits can play a key role in providing permeable pathways for enhanced production. Herein, we analyse the effects of bioturbation on the porosity and permeability of the Buda Formation, a highly bioturbated, tight (low-porosity matrix) Upper Cretaceous chalk reservoir from the Texas Gulf Coast Basin, which has been commercially exploited because of the occurrence of natural fractures. Our results show that (in addition to the natural fractures) burrows (and borings) substantially increased the porosity and permeability of this formation, thus, potentially contributing to enhanced hydrocarbon (or groundwater) storage and production. These biogenic structures might also have favoured the development of natural fractures and stylolites in the Buda Formation. However, further studies are required to prove this hypothesis.

Animal–substrate interactions preserved in ancient lagoonal chalk

Trace-fossil assemblages reflect the response of the benthos to sets of paleoenvironmental conditions during and immediately after sedimentation. Trace fossils have been widely studied in pelagic shelf and deep-sea chalk deposits from around the globe but never documented from ancient lagoonal chalk successions. Here we report the first detailed ichnologic analysis of a lagoonal chalk unit, using as an example the Upper Cretaceous Buda Formation from the Texas Gulf Coast Basin. In this unit, variable interconnection with the open ocean, accompanied by marked fluctuations in physicochemical parameters inherent to lagoonal circulation (e.g., salinity, hydrodynamic energy, bottom-water oxygenation), highly influenced the resultant trace-fossil content of the chalk. These lagoonal chalk deposits contain twenty ichnotaxa, displaying a clear dominance of Thalassinoides isp. and Chondrites isp., which are present in most of the bioturbated strata. The dominance of Thalassinoides isp., both in softgrounds as an element of the Cruziana Ichnofacies and in firmgrounds as a component of the Glossifungites Ichnofacies, highlights similarities with trace-fossil assemblages from shallow-water shelf-sea chalks. In contrast to both (open) shallow-water shelf-sea chalks and deep-sea chalks, the Buda Formation chalk exhibits more diverse assemblages and sharp fluctuations in ichnodiversity and ichnodisparity during relatively short periods of time. The increased ichnodiversity and ichnodisparity in this lagoonal chalk (in comparison with its open ocean counterparts) may reflect a complex interplay of taphonomic (i.e., incomplete bioturbation allowing preservation of shallow-tier trace fossils and ecologic (i.e., increased spatial environmental heterogeneity in the carbonate lagoonal setting) factors.

Sedimentology and stratigraphy of the Cenomanian Buda Limestone in central Texas, U.S.A.: Implications on regional and global depositional controls

The Cenomanian Buda Limestone is a distinctive rock formation widely distributed in Texas and its neighboring regions. The extensive character and regional significance of this unit make the Buda Limestone a key stratigraphic datum in the Texas Gulf Coast Basin. Detailed sedimentologic and stratigraphic studies of this formation were mostly focused on the west Texas exposures. In central Texas, on the contrary, very few studies have been performed. Thus, the sedimentary environments and depositional dynamics in this region are still poorly understood. Moreover, the regional correlation between the central and west Texas lithostratigraphic members of this formation remains unknown. Here, based on a detailed sedimentologic and stratigraphic study of central Texas sections (Austin-Kingsbury-San Antonio transect), the Buda Limestone is interpreted as a shallow-subtidal, semi-restricted to nearly open marine (lagoonal) shelf deposit. This unit is subdivided into two members (comprising 4th-order sequences S1 and S2) laterally variable in the study area. Vertical and lateral facies changes in the Buda Limestone are interpreted to be a function of the dynamic interaction of an irregular topography with fluctuating sea levels, under possible eustatic control. The informal (central Texas) “lower Buda” member is laterally correlated with the Lechuguilla Member (lower Buda) and Red Light Member (middle Buda) of western Texas. The informal (central Texas) “upper Buda” member, on the other hand, corresponds to the Love Station Member (upper Buda) from west Texas.

Solubility product constants for natural dolomite (0–200 °C) through a groundwater-based approach using the USGS produced water database

The calculation of a reliable temperature dependent dolomite solubility product constant (K_sp−dol) has been the subject of much research over the last 70 years. This study evaluates log₁₀(^aCa²⁺/^aMg²⁺) values using PHREEQC (Pitzer approach) for a screened subset (n = 11,480) of formation waters in the U.S. Geological Survey National Produced Waters Geochemical Database V2 (PWGD), an extensive inventory of 165,960 formational waters from a range of sedimentary lithologies in North America up to 6.6 km depth (Blondes and others, 2016). Through extensive ground truthing against datasets sourced from Texas Gulf Coast basin and the Mississippi Salt Dome basin we establish both the geochemical data from the PWGD and a new geothermal model of the US that is used to determine temperatures at-formation-depth to be reliable data sources. The vast majority (90%) of PWGD samples have log₁₀(^aCa²⁺/^aMg²⁺)-temperature values that are interpreted to be indicative of calcite-dolomite equilibrium and buffering by the bulk mineral solubilities. Using statistical models with different parameterisations (different Maier-Kelly formulas, mixed-effects models with various random effects and linear models) log₁₀(^aCa²⁺/^aMg²⁺) values are regressed against the estimated at-formation-depth temperatures to determine K_sp−dol between 0 and 200 °C. This process relies on the well constrained calcite solubility product constant (K_sp−cal). Local effects that modify log₁₀(^aCa²⁺/^aMg²⁺) values are evaluated through the addition of random effects to the mixed model which both improves the statistical reliability of the K_sp−dol model and enables the determination of K_sp−dol values for local dolomite phases. The nature of these local effects is open to interpretation, but we suggest the primary influence on log₁₀(^aCa²⁺/^aMg²⁺) values is the stoichiometry of the dolomite phase systematically modifying log₁₀(^aCa²⁺/^aMg²⁺) values. We discount the influence on log₁₀(^aCa²⁺/^aMg²⁺) values of dolomite order, the solution ionic strength, equilibration with anhydrite and chlorite group minerals, illitization of smectite and albitization of feldspar. For the dolomite solubility equation; the mixed-effects model (model J23) chosen as most representative yields a pK_sp−dol (log₁₀K_sp−dol); We determine pK_sp°−dol to be −17.27 ± 0.35 (25 °C, 1 atm) which is close to prior estimates, including the most recent experimental value reported by Bénézeth and others, 2018 (pKs_p°−dol = −17.19 ± 0.3) validating the groundwater regression analysis approach of this study.

Depositional environments and controls on the stratigraphic architecture of the Cenomanian Buda Limestone in west Texas, U.S.A.

The Cenomanian Buda Limestone is a widespread coccolith-rich carbonate unit deposited on the Comanche Shelf of the Texas Gulf Coast Basin. This formation is a key stratigraphic marker, and its hydrocarbon resources have been exploited since the 1920s. Despite its stratigraphic and economic importance, the depositional environments, and controls on the stratigraphic architecture of the Buda Limestone remain poorly understood. Here, based on the integration of high-resolution sedimentology, mineralogy and stratigraphy, the west Texas Buda Limestone is interpreted to be deposited in inner-neritic waters (likely < 40 m deep), of a lagoonal shelf (above SWB), with variable restriction (nearly open to slightly-restricted). Important thickness variations and oceanic-circulation were highly influenced by a wide, low-gradient paleo-shelf, in conjunction with local and regional paleo-structures (e.g., Terrel Arch, drowned Stuart City/Sligo reefal complex). Vertical facies variability, on the other hand, may be a function of orbitally-controlled, climate-driven sea-level fluctuations. The Buda Limestone is stratigraphically composed of two 4th-order (high-frequency) sequences (S1 and S2). The Lechuguilla and Red Light members belong to S1, whereas the Love Station Member corresponds to S2. The carbonate-richer Lechuguilla Member and Love Station Member (excluding its uppermost section) were deposited during transgressive periods possibly linked to higher temperatures and increased Earth's eccentricity. The clay-/quartz-richer Red Light Member, in contrast, was deposited during a regressive phase likely coupled with decreased Earth's eccentricity and a cooler climate. The carbonate-rich upper Love Station Member (uppermost 2.6 m), though deposited under similar conditions than the Red Light Member, was sedimented during an early HST phase with waters still warm and clear (low-turbidity) enough to promote the carbonate factory, as well sufficiently deep and energetic to prevent clay ponding. This study also provides solid evidence of subaerial exposure at the Buda Limestone bounding surfaces.

Quantitative seismic geomorphology, south Texas, United States

In this paper we use three-dimensional seismic attribute imaging and well data to reveal the previously unknown quantitative measures, directionality, and spatial locations of the Oligocene middle Frio fluvial channel systems within an area of 254 km2 (98 mi2) that covers two oil and gas fields in the Texas Gulf Coast Basin of the United States. The objective of this study is to apply quantitative seismic geomorphology techniques to quantify the morphometric parameters important to building predictive geologic models for fluvial reservoirs. Three categories of channel systems are differentiated based on their geomorphology, seismic signature, and the mode of transport. The first, category 1, includes channel systems of high-amplitude, moderate- to high-sinuosity, mixed load channels. Category 2 channel systems are high-amplitude, straight to low-sinuosity, bed load channels with both category 1 and 2 channels filled with coarse-grained sandstone deposits. Category 3 crevasse channel systems are low-amplitude, highly sinuous, suspended load channels filled with fine-grained deposits. These fluvial system categories were found to show unique morphometric characteristics such as channel width, meander belt width, and meander length. Analysis of the middle Frio channel systems imaged in the south Texas study area revealed a significant downstream decrease of channel belt width along the length of the channel belts. The creation of a quantitative morphometric database for the middle Frio fluvial reservoirs in the basin would be very useful for exploration and development purposes. The results of this study may have general applicability to the Texas Gulf Coast Basin and to similar fluvial reservoirs worldwide.

Climate, river network, and vegetation cover relationships across a climate gradient and their potential for predicting effects of decadal-scale climate change

Summary We determined present-day (1981–2000) relationships between river network drainage density ( D d ) and runoff ( R ), and between vegetation cover ( V ) and precipitation ( P ) across a contiguous 470,800 km 2 area (the Texas Gulf Coast basin), where P varies from 438 to 1280 mm/yr. D d ( R ) follows a saturation–growth model which is similar to process-based equilibrium landscape models. V ( P ) follows a linear relationship. The models for D d ( R ) and V ( P ) were used to assess how D d and V might respond to decadal-scale climate changes in R and P anomalies predicted by a regional climate model between 2041–2060 and 1981–2000. The regional climate model, CRCM, was forced following the SRES A2 emissions scenario. Our calculations indicate a tendency of 57,500 km of active river channels to drying up, representing 9.9% of the present-day total of 581,985 km, due to future decrease in R . This will be accompanied by a loss of 8150 km 2 in V due to decrease in P . This study extends empirical studies of relationships between climate and landscape properties and explicitly links observations with process-based models. The results provide a simple framework for modeling potential trajectories of the landscape due to climate change.

CO2 source-sink matching in the lower 48 United States, with examples from the Texas Gulf Coast and Permian Basin

Documenting geographic distribution and spatial linkages between CO2 sources and potential sinks in areas with significant levels of CO2 emissions is important when considering carbon-management strategies such as geologic sequestration or enhanced oil recovery (EOR). For example, the US Gulf Coast overlies a thick succession (>6,000 m [>20,000 ft]) of highly porous and permeable sandstone formations separated by thick, regionally extensive shale aquitards. The Gulf Coast and Permian Basin also have a large potential for EOR, in which CO2 injected into suitable oil reservoirs could be followed by long-term storage of CO2 in nonproductive formations below reservoir intervals. For example, >6 billion barrels (Bbbl) of oil from 182 large reservoirs is technically recoverable in the Permian Basin as a result of miscible-CO2 flooding. The Gulf Coast also contains an additional 4.5 Bbbl of oil that could be produced by using miscible CO2. Although the CO2 pipeline infrastructure is well-developed in the Permian Basin, east Texas and the Texas Gulf Coast may have a greater long-term potential for deep, permanent storage of CO2 because of thick brine-bearing formations near both major subsurface and point sources of CO2.

Evaluation of large-scale CO 2 storage on fresh-water sections of aquifers: An example from the Texas Gulf Coast Basin

Large-scale injections of CO 2 into subsurface saline aquifers have been proposed to remediate climate change related to buildup of green house gases in the atmosphere. The pressure buildup caused by such injections may impact a volume of the basin significantly larger than the CO 2 plume itself. In areas with hydrological settings similar to the Gulf Coast Basin, the perturbation of the flow-field in deep parts of the basin could result in brines or brackish water being pushed up-dip into unconfined sections of the same formations or into the capture zone of fresh-water wells. The premise of the current study is that the details of multiple-phase flow processes necessary to model the near field evolution of the CO 2 plume are not necessary to describe the impact of the pressure anomaly on up-dip aquifers. This paper quantitatively explores conditions under which shallow groundwater would be impacted by up-dip displacement of brines, utilizing an existing carefully calibrated flow model. Modeling an injection of water, arguably equivalent to 50 million tons of CO 2/year for 50 years resulted in an average water-table rise of ∼1 m, with minor increase in stream baseflow and larger increase in ground water evapotranspiration, but no significant change in salinity.

An empirically derived kinetic model for albitization of detrital plagioclase

We propose an empirically derived model that estimates the extent of reaction for albitization of plagioclase as a function of time, grain surface area, and temperature from 0 to 200°C. We use a kinetic formulation independent of pressure, and consistent with the Rate Law, which quantifies the dependence of the reaction rate on the initial concentration of the reacting material, and the Arrhenius equation. The formulation is described by the function: \[{-}\frac{d{[}An{]}}{dt}{=}S_{m}k{[}An_{o}{]}^{2}(1{-}{\bar{{\Omega}}})\] where d[An]/dt is the rate change of the anorthite mole fraction with time, Sm the mineral surface area (cm2), k the rate constant 1/cm2 s, [Ano] is a constant representing the initial anorthite mole fraction, and Ω a constant weighed average saturation index. We derive the apparent activation energy (Ea) and frequency factor (A), both present in the rate constant k, by fitting them to the extent of albitization measured in 11 samples from the San Joaquin Basin. Subsequently, we test the model against two independent albitization trends, one from the Texas Gulf Coast basin and one from the Denver Basin of Colorado. Our results indicate that albitization in all three basins can be fit by an Ea of 68 ± 4 kJ/mole and A of (6.5 ± 0.5) × 103 1/cm2 Ma. The rate dependence on temperature is consistent with experimental values for albite crystal growth and with empirically derived precipitation rates of other diagenetic silicates such as illite and quartz. The parameters and fit suggest that albitization can be modeled as a surface controlled reaction, primarily dependent on temperature.

Petrophysical Properties and Geology of Selected Intervals in the Frio Formation, Stratton Field, South Texas for Modeling Interwell Seismic Logging Response: ABSTRACT

ABSTRACT Seismic or continuity logging consists of locating a seismic source in one borehole near or in a low-velocity layer and deploying a detector array in a second borehole. Detection of guided waves transmitted between the two wells indicates bed connectivity. The guided wave signatures are either leaky modes or normal modes (or both). The technique has numerous applications in various types of heterogeneous geological environments, including many Gulf Coast gas reservoirs. It can be used to determine the continuity of beds between wells, estimate and locate variations in the thickness of beds, and estimate the average rock physical properties of the beds. Stratton field was selected as the Gulf Coast gas-play type field for a project to model interwell seismic logging responses. Stratton is a mature gas field located in the south Texas Gulf Coast, about 30 miles southwest of Corpus Christi. It encompasses over 120,000 acres in portions of Kleberg, Nueces, and Jim Wells counties. Stratton is one of 29 fields in the Frio Formation fluvial-deltaic play associated with the Vicksburg fault zone along the Texas Gulf Coast Basin. This poster presentation explains the technique of interwell seismic logging, documents the petrophysical properties and geology of intervals in the upper and middle Frio, and presents the results of the forward modeling tests. End_of_Record - Last_Page 472-------

Differences in the Stratigraphic Framework of the Frio and Anahuac Formations in the Louisiana and Texas Gulf Coast Basin: ABSTRACT

ABSTRACT The hydrocarbon endowment of the Frio and Anahuac Formations of Louisiana and Texas has made them the most thoroughly studied geologic strata in the Gulf Coast Basin. A review of previous studies of the stratigraphic frame-work of the Frio and Anahuac Formations in the Louisiana and Texas Gulf Coast Basin reveals that researchers have placed the boundary between the Frio and Anahuac in this basin at different biostratigraphic and lithostratigraphic levels. This review also reveals that in some previous studies the subdivision of the Frio in Texas into lower, middle, and upper zones does not conform to the traditional biostratigraphic zonation scheme. The index fossils used to mark the boundary between the Frio and Anahuac differ in the Texas Gulf Coast from those employed in the Louisiana Gulf Coast. In the sub-surface Frio of Louisiana, the paleontologic top of the Frio is historically placed at the highest occurrence of Camerina sp. A. In the subsurface Frio of Texas, the paleontologic top of the Frio is historically marked by the highest occurrence of Cibicides hazzardi. Although microfossils characteristic of the Camerina A zone are reported from wells penetrating the subsurface Anahuac and Frio, their occurrence has proven too erratic to be employed in a regionally correlatable biostratigraphic framework. This review also shows that some workers place the lithostratigraphic top of the Frio in the Texas Gulf Coast Basin just above the first sandstones lying below the Anahuac shale wedge. These sandstones are actually lower Anahuac Marginulina sandstones in the lower and middle Texas Gulf Coast and upper Frio Cibicides hazzardi sandstones in the upper Texas Gulf Coast, depending on the dip position of the particular well. End_of_Record - Last_Page 758-------

Depositional Environment of the Downdip Queen City (Eocene) Sandstone, Mestena Grande Field Area, Jim Hogg and Duval Counties, Texas: ABSTRACT

ABSTRACT The downdip Queen City sandstone interval in the Mestena Grande field area of the south Texas Gulf Coast Basin comprises two sandstone depositional units, referred to herein as A Lobe and B Lobe. A total of 583 ft (179 m) of conventional core from 11 wells containing predominantly B Lobe deposits was examined macroscopically. The A Lobe is a thin (6-34 ft; 1.8-10.4 m) fine- to very fine grained, mostly bioturbated, well-sorted sandstone. The B Lobe is composed of fine to very fine, well-sorted sandstone interbedded with siltstone and mudstone. The trace fossil assemblage of the B Lobe indicates that sediments were deposited in the Cruziana ichnofacies. Trace fossils and authigenic minerals also suggest oxygen stratification during deposition. The B Lobe contains five subunits, each as much as 13.5 ft (4 m) in net sandstone thickness. These units were deposited as part of a highstand systems tract during the early Lutetian Stage (early middle Eocene). The B Lobe is a primarily aggradational unit composed of storm-generated sandstone and heterolithic deposits of the lower shoreface to inner shelf environment. The A Lobe is an upward-coarsening unit that represents progradation of the shoreface during late highstand systems tract development. An interlobal mudstone, which separates the units, marks the transition from early to late highstand systems tract development. End_of_Record - Last_Page 767-------

Approaches to Finding New Gas in Mature Fields: An Example from the Middle Frio, Onshore Texas Gulf Coast Basin

ABSTRACT Refined depositional models of reservoir distribution applied to new and previously acquired data sets (reflection seis mic, well logs, and core) can lead to potential infield opportunities. Conventional 2-D seismic and well logs are standard industry tools utilized as part of many exploration and field-development programs. Reflection seismic lines across a 50-yr-old gas field along the Vicksburg fault trend of the Gulf Coast Basin in a non-marine portion of the Oligocene Frio section, were interpreted with emphasis on changes in waveform character. A comparison of velocity-only derived synthetics to velocity/density derived synthetics show a close similarity. Observed amplitude variations are non-fluid related but are lithology and thickness dependent. Synthetic seismograms constructed for well logs and tied to conventional reflection seismic lines were correlated with stratigraphic cross sections and facies maps. Standard resistivity logs, typically available for all well control, can be digitized to create pseudo-synthetics for well to seismic correlations where velocity and density logs are unavailable. Observed patterns of variation in seismic character were linked to geologic interpretation from well logs. Seismic variations range from single waveform peaks (15 milliseconds) that correspond to isolated 45 ft+ channel complexes to zones of 3000 ft wide convex reflections (40 milliseconds or 200 ft thick) that correspond to variable lithologic patterns across part of the field. Both vertical and lateral transitions from sandstone-rich amalgamated channel sequences to sandstone-poor non-channel areas are the dominant explanation for reflection contrast. High amplitude reflectors are mappable along a 2-D grid with an approximate 2000 ft spacing. Comparison of known gas productive intervals at moderate depths (4000 to 7000 ft) from the existing well control with the detailed geologic and seismic interpretation reveals a combination of potentially untapped and partially drained portions of multiple reservoirs that warrant consideration for infield drilling or recompletion. Combined interpretation of well logs, reflection seismic data, and production information is a simple, cost-effective approach to utilizing standard tools and information in a mature field to locate opportunities for incremental gas recovery. End_of_Record - Last_Page 407-------

Facies Heterogeneity, Pay Continuity, and Infill Potential in Barrier-Island, Fluvial, and Submarine Fan Reservoirs: Examples from the Texas Gulf Coast and Midland Basin: ABSTRACT

Facies Heterogeneity, Pay Continuity, and Infill Potential in Barrier-Island, Fluvial, and Submarine Fan Reservoirs: Examples from the Texas Gulf Coast and Midland Basin: ABSTRACT

Estimation of Uncertainty in Coal Resources: ABSTRACT

The use of alternate energy sources to supplement dwindling domestic petroleum resources will increase in the future. Among alternate resources, coal will contribute greatly to the future energy mix. Official estimates of the United States coal resources published during the past 15 years range from less than 1.7 to as much as 3.9-trillion short tons (1.5 to 3.5-trillion metric tons). These differences imply that a high degree of uncertainty exists in resource assessment. A comparison of variability in coal resource estimates in areas of different ancient depositional environments is examined in an attempt to utilize depositional systems for improved coal resource estimates. The Texas Gulf Coast basin was chosen to develop the methodology of resource evaluation because it exhibits a full range of ancient depositional environments. Two lignite deposits are evaluated, one from the alluvial plain setting of the Wilcox Group in east Texas and the other from the delta plain setting of the Jackson Group in east Texas. Important sources of uncertainty in resource estimation include variability of seam thickness and areal distribution. To test the degree of uncertainty caused by variations in seam thickness, the numbers of boreholes considered in each lignite deposit are reduced and resources are calculated for each reduction in data. Classical statistical methods are used to determine the number of boreholes required to obtain resource estimates of individual seams within a given confidence interval and specified conditions. Geostatistics (variograms and kriging) are used to measure variability in resource estimates. These studies show that the minimum number of boreholes required to characterize coal resources within an accuracy of 20% for example, is substantially less than might be expected intuitively, and that the degree of assuredness depends on the coefficient of variation of the data analyzed. End_of_Article - Last_Page 1678------------

Depositional Systems in Jackson Group of Texas Gulf Coast Basin: ABSTRACT

Regional outcrop and subsurface investigation of the Jackson Group in Texas indicates development of 5 main depositional systems. Dominant element in the central and east Texas Gulf basin (bounded by Guadalupe River on the south and Neches River on the End_Page 1783------------------------------ east) is the Fayette fluvial-delta system consisting of dip-oriented, lobate wedges of sand, mud, and lignite. The vertical sequence in updip subsurface and outcrop, with gradation upward from marine mud through several delta facies and into fluvial sand and mud, reflects net regression and progradation of the system. Southwestward, transport of sand and mud from the delta system, principally by longshore drift, resulted in the South Texas strandplain-barrier bar system, made up of strike-trending sand bodies interbedded with marine and lagoonal mud. Landward of the strandplain-barrier-bar system and extending into outcrop is a complementary lagoonal-coastal plain system consisting of mud and minor, dip-oriented sand units. Gulfward of the strike-trending strandplain system is the Sou h Texas shelf system, formed by marine mud derived largely from the delta system on the northeast. Beneath the South Texas strandplain-barrier bar and Fayette delta systems and extending eastward into Louisiana and Mississippi is the Caddell-Yazoo shelf system consisting of marine, fossiliferous mud and minor glauconitic marl. Delineation of depositional systems, and specifically component facies of the various systems, facilitates definition of significant mineral trends (oil, gas, lignite, and uranium) that show the relation between current and potential areas of production. End_of_Article - Last_Page 1784------------