High Total Organic Content Research Articles

Sedimentation rates and pollution history of the eastern Mediterranean Sea: Syrian coast

Sedimentation rates along the Syrian coast were determined by the 210Pb dating method to a total of nine cores taken in 1993; rates were found to vary between 0.11 and 0.87 cm year −1. These rates were used to provide historical records of the total organic content, major elements such as Al, Ca, Fe, K, Mg, Mn, Na, Ba and Br and some trace metals (As, Cr, Pb, Zn and Cu) concentrations along the Syrian coast. High total organic content up to 52% was found near Banias City; the Banise oil refinery and oil export activities were identified to be the pollution source of that area. Down core concentration profiles of trace metals show an increase in the concentrations of As and Cr in the upper layers for some of the collected cores. The highest values measured for As and Cr were 186 and 380 ppm, respectively, which are much higher than the natural levels. These high levels may be due to discharges of chemical wastes either from ships or coastal factories. However, the data can be used as a base background level for a future marine monitoring program of the Syrian coast.

Heterogeneity of the Organic Matter in the Guayuta Group, Eastern Venezuelan Basin

The purpose of this study is to evaluate the organic matter heterogeneities in the Guayuta Group as a principal hydrocarbon source rock in the Eastern Venezuelan Basin. In order to do this, thirteen wells and five work stations on outcrops of the Interior Mountain Belt were analyzed to study the regional and vertical variations in the geochemical characteristics of the organic matter. It is possible to detect significant differences in quality and quantity of the organic matter which could corroborate the regional development of two organic facies from North to South in the Maturin Subbasin. The northern organic facies show excellent characteristics as source rock. The study of vertical distribution of organic matter was carried out in a well of northern part of the Monagas state, which represents the southern organic facies. It shows an irregular input of continental organic matter, thermally immature. Besides the organic matter content was low (around 1.5%) without depth tendencies. These sediments are clastic and bioclastic in contrast with carbonates and pelagic shales of the Guayuta Group in the Interior Mountain Belt. The outcrop samples studied show a high total organic content (2-6%) despite the high maturity determined on kerogen. The systematic study of thismore » geochemical parameter show pseudocyclic relationships with a general tendency to increase toward the bottom of the section. V, Ni, and S determinations could indicate that anoxic conditions were developing toward the North where the marine organic matter was sedimenting. The results of this study are in agreement with paleogeographic model of sedimentation during middle and late Cretaceous, with sources of sediments from South and a progressive depth of the basin toward the North.« less

Development of the Austin Chalk in Giddings Field, Burleson County, Texas, by Horizontal Drilling

ABSTRACT The Austin Chalk produces in a NE-SW trend, sub-parallel to the Texas Gulf Coast, in a band approximately 523 km. (325 mi.) long and 40-64 km. (25-40 mi.) wide. Giddings Field is located in the central part of this trend and covers a portion of several counties along the productive fairway. The Austin Chalk produces from a hard, dense, intensely fractured limestone with a matrix porosity range of 3-8% and permeabilities of less than 0.01 md. Production comes primarily from the fractures with contribution from the matrix coming later in the life of the well. The Austin Chalk was deposited near the southern end of the Cretaceous western interior seaway during the Coaniacian and Santonian ages (late Commachean to early Gulfian series) on a stable, gently dipping ramp during a high stand of sea level. The Austin was deposited as a calcareous ooze made up of coccoliths, coccolith fragments, planktonic foraminifera, and fine grained skeletal debris. The Austin is poorly to intensely burrowed and contains organic rich interbedded shale layers with gradational to sharp contacts with the intervening cleaner limestones. The high total organic content indicates the potential for the Austin Chalk to have been partially or completely self-sourced. As a result of the development and improvement of horizontal drilling techniques, the Austin Chalk has experienced a flurry in drilling activity. This boom began in Pearsall Field in the southern end of the trend and soon spread to the northeast to Giddings Field and beyond. Several different methods such as drilling a highly deviated hole or traverse across the Austin, drilling parallel to faulting, stair-stepping across different zones of interest, or drilling in a specific target for the entire well path have been tried (along with other ideas) with varying degrees of success. There are many different questions to be answered before drilling a horizontal well. Consideration should be given to off-set production, presence or absence of faulting, and thickness of the target zone to name just a few. The parameters and guidelines used in one area may not work the same way in a different area or in a different part of the same field. Seismic should be used in choosing locations and in evaluating areas of interest where there is limited subsurface control. For a typical horizontal chalk well, casing is set into the top of the Austin 6-9 meters (20-30 feet) at some predetermined angle which will allow for getting into the target zone as soon as possible. If needed, a tangent section is then drilled before continuing to build angle to reach the center of the target. The well is then drilled to the planned measured depth and completed. Early wells were cased but due to cost and the nature of the reservoir the subsequent wells were completed open hole. The early horizontal wells were drilled with lateral sections less than 609 meters (2000 feet). Improvements in drilling techniques have enabled operator to drill lateral sections greater than one mile. Both old and new methods are used for formation evaluation of the horizontal wells. Careful evaluation of the cuttings and close monitoring of the penetration rates and gases are critical in determining if the lateral section is being drilled in the right zone in identifying fractured intervals and in qualifying shows. New borehole imaging tools produce a visual record of the borehole and are good direct measurement indicators of fracturing along the well path. The data gathered from these logs can be used in many ways to aid in evaluation of the play. End_of_Record - Last_Page 801-------

Source Rock Potential of Fine Sediment Deposited in Eleuthera and San Salvador Deep-Sea Carbonate Fans, Bahamas: ABSTRACT

Organic matter analyses were conducted in late Quaternary fine sediments deposited in Eleuthera and San Salvador deep-sea carbonate fans (water depth ranging between 4000 and 5000 m) at the mouth of the two largest canyons draining most of Great and Little Bahama Banks. Higher content and better quality of organic matter are generally observed in fine carbonate turbidite material than in the intervening hemipelagic carbonate ooze or mud. The hemipelagic carbonate ooze and mud (carbonate content between 80% and a few percent) are made of a mixture of planktonic tests, bank-derived fine aragonite and magnesian calcite, as well as fine terrigenous material transported southward from the North Atlantic by the Western Boundary Current. Their TOC (total organic content) values are low (in average between 0.30 and 0.45%). The organic matter quality is poor due to important alteration during a long transport and slow burial. The TOC values of the carbonate muddy turbidite, made almost exclusively of bank-derived fine aragonite and occurring in the valleys and lobes of Eleuthera mid-fan, range between 0.25 and 1.80%. The highest TOC values (1 to 1.8%) were measured in the most recent events (younger than 6000 y.B.P.), where the organic matter is exceptionally fresh duemore » to the turbiditic sedimentation which prevents biochemical alteration. Its global composition is closer to the average composition of living marine organisms than the composition of common recent marine sediments. Its source rock potential for hydrocarbon generation is thought to be high, and the intervening turbidite layers made of carbonate sands and gravel could serve as local reservoirs.« less

The agronomic value of the sewage sludge of Tenerife. Physico-chemical characteristics of the refuse-sludge compost and related products

This paper evaluates the most important agronomic characteristics of the sewage sludge from the Tenerife wastewater treatment plant and the compost obtained by composting of this sludge with the organic fraction of municipal refuse. A comparative study is also carried out on several commercial products used as organic dressings on the island's agricultural soils. From the results obtained, the direct use (after sterilization) of sewage sludge could be very interesting from the agricultural point of view. The compost obtained, because of its high total (43·6%) and oxidisable (37·3%) organic matter content, its high fertilizer elements concentration (N, 2·8%; P, 1·3%; K, 1·6%; Ca, 5·2% and Mg, 1·1%), its balanced essential elements content and moderate toxic heavy metals levels, can be considered a good organic fertilizer whose use could represent a great saving in chemical fertilizers and replace the manures formerly used, which are now almost non-existent. In addition, it could compete advantageously with the products at present on sale in the island because of its lower cost and better agronomic quality.