|Theme||Visible||Selectable||Appearance||Zoom Range (now: 0)|
A gas facility encompasses the equipment between the gas wells and the pipeline or other transportation method. The purpose of the gas facility is to remove impurities and contaminants from the gas, remove liquids and solids, and prepare the gas to meet the sales requirements of the purchaser. Figure 1 is a block diagram of a simple gas facility. Each of the main blocks is described here. The gas must be treated for sales or disposal.
Many data are interpreted to evaluate a petroleum-bearing formation, and we discuss the interpretations of data acquired through surface data logging in terms of the rock formation and fluid properties they help determine. The logging engineer or geologist gets information about the formation fluids directly from fluids that are released into the wellbore while drilling and circulating out suspended immiscibly in the drill fluid or remaining in the pores of larger cuttings that may not have been flushed. They receive information indirectly from remnants of the fluid that remain in pores of rock cuttings, as stains on the grain surface, or in solution in the drilling fluid. Oil may be identified as a sheen on the surface of water-based drilling fluid. If the circulating fluid density is sufficiently low as to render an underbalanced drilling condition, oil may be produced in large enough quantities that a sample may be skimmed off a whole mud sample.
Brazilian state-owned Petrobras announced on 29 January it had discovered hydrocarbons in a well located in the Campos Basin presalt off Brazil's coast of Campos dos Gotyacaze in the State of Rio de Janeiro. Well 1-BRSA-1377-RJS (informally called Urissanê) is located in Block C-M-411, at a depth of 2950 m approximately 200 km offshore. Petrobras, which operates the block in a 50/50 partnership with ExxonMobil, said it would analyze the well data to better target exploratory activities and assess the potential of the discovery. The hydrocarbon discovery was the first of the year offshore Brazil. In 2020, a total of 10 offshore finds were reported to the National Agency of Petroleum, Natural Gas and Biofuels (ANP), the last of them in December in the Búzios field.
One role of the petrophysicist is to characterize the fluids encountered in the reservoir. Detection of a change in fluid type in the rocks while drilling is usually straightforward with the use of gas and chromatographic measurements. Gas shows and oil shows while drilling are time-honored indicators of zones that need further investigation through logs, testers, and cores. In the rare case of gas-bearing, high-permeability rock drilled with high overbalance, gas will be flushed from the rock ahead of the bit, will not be circulated to the surface in the mud, and will not produce a gas show. Because hydrocarbons are not always part of a water-based-mud formulation, sophisticated analytical chemical techniques can be used on the oil and gas samples circulated to the surface and captured to determine the properties of hydrocarbons in a given zone penetrated by the drill bit.
Knowledge of the dissolved constituents is important because these constituents are related to the origin and/or migration of an oil accumulation, as well as to the disintegration or degradation of an accumulation. The concentrations of organic constituents in oilfield brines vary widely. This page discusses the occurrence of dissolved gases, organic constituents, and dissolved solids in produced water. Large quantities of dissolved gases are contained in oilfield brines. Most of these gases are hydrocarbons; however, other gases such as CO2, N2, and H2S often are present.
The refrigeration process is used in gas plants to remove heat from certain process streams. Refrigeration in natural gas treating is a process that serves a dual dewpoint control function--namely, it is used to meet the hydrocarbon dewpoint as well as the water dewpoint specification for residue or sales gas. The temperature to which the gas is cooled depends first on meeting these dewpoint specifications. This is the minimum cooling requirement. Cooling the gas to lower temperatures than the minimum temperature for dewpoint control has to be justified by the economics of liquefied petroleum gas (LPG) recovery. This requires a cost analysis of the value of additional LPG recovery versus increased capital and operating costs. Refrigeration is basically pumping heat from one medium to another.
Scanning a series of samples laid out on the counter allows the logger to get a good overview of trends, to highlight sample differences that may be the result of quality variation or contamination, and to help identify bed boundaries. Individual samples are then examined under a low-power stereomicroscope (10 to 50X) with either ample natural light or a lamp with a "blue" light or blue filter. Proper illumination is required so that the true colors of the sample constituent minerals are not distorted. Digital image capture of select samples adds significantly to the end-of-well documentation.
Unlike conventional reservoirs, coal seams are the source, trap, and reservoir for coalbed methane (CBM). A comparison of the two reservoir types shows profound differences in reservoir properties, storage mechanisms, flow mechanisms, and production profiles. Understanding the reservoir differences is key to successful evaluation and operation of a CBM project. Coal is a chemically complex, combustible solid consisting of a mixture of altered plant remains. Organic matter constitutes more than 50% of coal by weight and more than 70% by volume. Type refers to the variety of organic constituents.
Biodegradation occurs when bacteria, fungi, or other organism or biological process chemically dissolves materials. The process can be beneficial or detrimental within the industry depending on the circumstances. For instance, biodegradation via bacteria can aid in the cleanup of oil spills. The process can take more or less time depending on the amount of type and amount of bacteria, the reservoir or ecosystem in which the bacteria are found, and the amount of oxygen present. In reservoirs cooler than approximately 80 C, oil biodegredation is common and detrimental.
Microbial Exploration Technology (MET), also called microbial enhanced oil recovery (MEOR), is a method of enhanced oil recovery (EOR) that identifies microorganism levels in soil near reservoir surfaces to estimate hydrocarbon levels. This method is largely based on the premise that the more microorganisms present, the more hydrocarbons are present for those microorganisms to feed on. Hydrocarbon degrading bacteria can be used to detect migrating hydrocarbon gases from oil and gas deposits. As short chain hydrocarbon gases migrate to the surface, bacterial cells metabolize these gases in the near surface aerobic zone. In the laboratory, EBT measures the response from these hydrocarbon utilizing bacteria and develops their recommendations based on a proprietary data analysis process.