Deep Water Pressure Research Articles

Influence of Physical Sensitizing Agent on Compression Resistance of Deep Water of Emulsion Explosives

A study of emulsion explosive of deep-water pressure performance can provide theoretical basis for underwater blasting, deep hole blasting and the design of emulsion explosive. The sensitizer is the heavier components of emulsion explosive, using reusable experimental device to simulate the environment of deep water charge, perlite and glass microspheres in two kinds of commonly used physical sensitizing agent content on properties of emulsion explosives with deep water pressure effect. The experimental results show that : with the increasing of the content of physical sensitizing agent, emulsion explosive of deep-water pressure performance also gradually improve, when the pressure is larger, the effect is particularly pronounced; in a certain range, with the increase of the content of physical sensitizing agent, emulsified explosive performance also gradually improve, but reaches a certain value, the explosion properties but declined; in emulsion matrix under the same conditions, the perlite content of 5%, glass microspheres content is 2%, the emulsion explosive has good resistance to water pressure and explosion properties.

Possible Alternatives for Deep-Water Gas Charged Accumulators

Gas Charged Accumulators are widely used in Drilling operations; however, the current Accumulator design methods are inadequate for Deepwater Drilling. Gas-Charged Accumulators are used in subsea drilling as well as production operations. One important application of accumulators is in blowout preventers (BOPs). BOP’s are designed to shut in a well under pressure so that the well control procedures could be implemented. Control Systems for the BOPs should be highly efficient hydraulic systems and operate in as short a time as possible. Supplying enough volume of pressured hydraulic fluid to operate those emergency functions is essential. To have the necessary quantity of control fluid under pressure requires storing this fluid in accumulators. Gas Charged Accumulators are the most commonly used accumulators in Drilling operations. These accumulators are not efficient at all in Deep waters, and there are not many alternatives for them. This paper looks into possible alternatives for Gas Charged Accumulators in Deep Waters. Supplying enough volume of pressurized hydraulic fluid to operate the BOPs for emergency situations is essential for Deep Water Drilling. This requires storing the pressurized hydraulic fluid in accumulators. A problem may arise when the wellhead is at water depth of more than 3500 ft. In deep water drilling, the accumulators should be placed on the subsea BOP stack to reduce hydraulic response times and provide a hydraulic power supply in case of interruption of surface communication. Hydraulic fluid capacity of an accumulator may drop to 15% of its capacity on the surface and even less, depending on the water depth. The reason for this is that the nitrogen gas does not behave like an ideal gas as we go to very deep water, due to high hydrostatic pressure at that water depth. We have to look for alternatives to Gas Charged Accumulators. It has to be something that is able to store energy, but unlike the nitrogen, its functionality should not be affected by the increasing hydrostatic pressure of water. The possibility of the use of springs and heavy weights as possible replacements for nitrogen in structure of accumulators will be discussed in this paper. High hydrostatic pressure of deepwater should not affect the functionality of these mechanical accumulators. Transferring bank of accumulators to the surface and connecting them to the BOP with properly sized and rigid pipes can decrease response time to an acceptable extent to satisfy regulations and standards. This idea can be considered as an alternative solution too. We have to include the hydrostatic pressure of water in the usable fluid calculation. A low pressure tank located on the sea-floor can dismiss the negative effect of high hydrostatic pressure of seawater. This alternative idea is also discussed. Efficient deep water accumulators would reduce the number of accumulators required in deepwater and cut the cost of the project. With the advent of such efficient accumulators, we can hope that one of the numerous problems of deepwater drilling has been solved and we can think of drilling in even deeper waters. Key words : Drilling operations; Deep-water gas charged accumulators; BOPs

Experimental and Numerical Study of the Effect of Surround Protection Technique on the Strain Measurement for Offshore Jacket Platform

For strain measurement on offshore jacket platform in deep water, waterproof of strain foil is always an important issue, especially, due to the high pressure in deep water. The waterproof is difficult in two places, one is between the matrix structure and the protection structure, and another is between the lead wires and the protection structure. The surround protection technique discussed in this paper is conventional and ideal, and can be operative for a long time, up to five years. In this method, a metal case and tube is added on the local position, which increases the local rigidity, but the effect on the measurement of strain is not well studied. In this paper, the effect of the surround protection technique on the strain measurement is studied by using numerical and experimental methods, and the results show that the measurement error is well in the range permitted by engineering practice.

Abstract: A Research Project Documenting the Pressure History of an Overpressured Basin - Application to Deep Water Pressure

Abstract: A Research Project Documenting the Pressure History of an Overpressured Basin - Application to Deep Water Pressure

Uses of Pressure and Temperature Data in Exploration and Now Developments in Overpressure Detection

Distinguished Author Series articles are general, descriptiverepresentations that summarize the state of the art in an area of technology bydescribing recent developments for readers who are not specialists in thetopics discussed. Written by individuals recognized as experts in the area, these articles provide key references to more definitive work and presentspecific details only to illustrate the technology. Purpose: to informthe general readership of recent advances in various areas of petroleumengineering. Summary. Pressure and temperature data from wireline logs andseismic-velocity analysis can be used in deep overpressures to aid in prospectevaluation. Properly interpreted seismic-velocity analysis in deep water canyield maturation and migration information. Use of a modified approach to the dexponent and use of measurement-while-drilling (MWD) data have provedsuccessful in deepwater pressure detection. Introduction Abnormal pressure prediction, detection, and confirmation have been in usefor a number of years. Ho and Johnson's and Wallace, papers in 1965 originateda whole new technology with great economic value that is difficult to assess interms of dollars. Pore-pressure work is similar to corrosion engineering. Noone pays attention as long as everything is working, but everyone notices ifsomething goes wrong and a disaster occurs. Pore-pressure and corrosionengineering are designed to eliminate the cost of fighting a problem. Pressure-detection work started with the d exponent and confirmationtechniques with wireline resistivity, conductivity, and acoustic togmeasurements. Cuttings density, gas, and flowline temperature followed asdetection parameters. Prediction from seismic-velocity analysis also wasdeveloped. The basic methods apply to many enshore and offshore basinsthroughout the world; however, the pressure-estimating techniques vary frombasin to basin and sometimes within a basin. This paper presents an overview of the traditional methods used, as well asnew concepts that apply to the use of pressure and temperature data toexploration. These data can be used in preacquisition evaluation as anothermeans of rating prospects. The methods described can be used to re-evaluatecurrently owned acreage before committing to drill deep, costly exploratoryholes. The techniques discussed can be applied to clastic basins, where thickoverpressured shale sections occur, in addition to the Gulf of Mexico. In theGulf of Mexico, the top of overpressure varies from 18,000 ft [5486 m] belowthe mudline to less than 1,000 ft [less than 305 m] below the mudline. Depth tothe top of overpressure generally decreases with distance from the depocenterin any overpressured basin, and the magnitude of the pressure gradient at anygiven depth increases. This is a direct result of the decrease in the volume ofpermeable sediment deposited farther from the shoreline. Traditional Methods Pore-pressure detection with drilling parameters works well in clasticbasins. Fig. 1 is a schematic showing the response of various parameters thatcan be measured during drilling. Rate of penetration (ROP) shows an increasewhen a transition zone in shale is encountered during drilling with stabledrilling parameters (bit weight, rotary speed, mud weight, and hydraulics). Theincrease in ROP with rock bits is caused by the increase in fluid content ofthe shale below the pressure seal (or caprock) plus the decrease inoverbalance. The d exponents is a normalizing technique that minimizes theeffect of changing drilling variables, and the modified d exponent, d, can bequantified empirically for estimating pressures. There is no dc-vs.-pressurecorrelation that works everywhere, but the matrix-stress technique forestimating overpressures can be used in many areas when used properly. Weightper inch of bit diameter, W/D, should also be monitored bemuse large changes inW/D on a bit run can exceed the ability of the d c exponent compensate and atrend shift may be required. Other "on-bottom" indicators that are used includetorque and fill, which may increase when the well becomes underbalanced andshale sloughing occurs. The final on-bottom indicator used is a flow check. Other parameters can be monitored as the mud is circulated to the surfaceand then properly lagged to provide data that are "behind" tie bit. Lithologymust be monitored and is a gross indicator of a possible pressure transitionfrom nominal to above-normal pore pressure. No transition zone is likely tooccur when porous sediments dominate the lithology column. JPT

Gravity-wave-induced pressure fluctuations in the deep ocean

We establish a mathematically consistent theory of the pseudosound pressure fluctuation (below 1 Hz) in the deep ocean induced by nonlinearly interacting random plane waves on the surface. In the process, a new set of second-order perturbation equations is derived. A phenomenological model is adopted for wind pressure which serves to excite a two-component surface-wave field, namely wind-driven sea and swell. By solving the perturbation equations through second order with this wind pressure as the excitation, we obtain an expression for the deep water pressure fluctuation and its power spectral density in the gravity-wave regime. Contrary to the previous theory not all of the surface waves contribute to the generation of the pressure fluctuation. Only the swell component does. Moreover, the customary Gaussian-distribution assumption of the surface waves leads to an incorrect power spectrum of the pressure. A more general probability distribution is required for obtaining a meaningful power spectrum formula. [This research has been supported by the Office of Naval Research, Code 480.]

Oceanic volcanism: A review

Recognition of the magnitude and tectonic significance of oceanic volcanism has recently stimulated intensive investigation of the volcanic rocks and structures of the sea floor. An adequate interpretation of these features depends on a thorough understanding of submarine volcanic mechanisms. The pressure of deep water restricts the amount of vesiculation of eruptive magmas so that explosive activity is suppressed. Pillow lavas are probably shorter but thicker than subaerial flows of the same composition. Fragmental hyaloclastites are also important, but seem to be most common at relatively shallow depths. Most lavas and hyaloclastites are basaltic, but more siliceous pyroclastic deposits may be common in shallow seas of the continental shelves.Circumstantial evidence indicates that most abyssal basalts of the ocean floor were erupted at spreading centers and have been transported laterally. The rate of eruption of lavas is probably related to the mechanism of dike intrusion into a spreading center. Slow spreading rates result in less vertical transfer of heat, so that only relatively thick dikes reach the surface. Thinner dikes are chilled before erupting and cause a differential dilation of the crust that is reflected in shallow normal faulting. With increasing spreading rates, wall rocks are maintained at higher temperatures, and almost all dikes reach the surface to produce lava flows and smoother topography.Seamounts may begin to grow at ridge crests and continue as the volcano moves outward, but many must begin their activity far from the spreading center. Most of the submarine structure of seamounts must consist of pillow lavas with increasing amounts of hyaloclastites in the upper portion. Injection of dikes and sills adds substantially to the volume of the structure.Most abyssal basalts erupted at ridge crests are tholeiites, commonly with relatively high alumina contents. Silica‐deficient alkaline basalts become more common outward, especially at the crests of seamounts. The ultramafic rocks dredged from the mid‐Atlantic ridge fall into two classes. Some are clearly cumulate rocks related to associated gabbro and differentiated basalt. Others are strongly depleted in low‐melting components and appear to have been emplaced along fault zones; they may be derived from a residual layer from which basalt was extracted during an earlier episode of partial melting. It is difficult to find conclusive evidence that oceanic volcanism was as intense in pre‐Mesozoic time as it is postulated to be today.

Microbiological Activities at Low Temperatures with Particular Reference to Marine Bacteria

A LTHOUGH it is frequently stated in the popular as well as in some scientific literature that the ocean floor beyond the continental shelves is barren of bacterial life, primarily due to the lack of food and the prevailing low temperature and high hydrostatic pressure, investigators have almost invariably demonstrated the presence of an abundant bacterial flora in bottom deposits wherever critical analytical procedures have been applied. In fact, there are usually from ten to ten thousand times as many viable bacteria per gram of mud as there are in a corresponding quantity of water in any superimposed strata. While nearly all of the studies on marine bacteria to date have been made in relatively shallow water near land, a few workers have recovered significant numbers of living microorganisms from mud collected at depths of a mile or more. However, the recovery of organisms from such depths is by no means incontrovertible proof that these organisms are biochemically active in such an environment, because they may be merely passive inhabitants which have settled from above and have been preserved by the cold. Inasmuch as over four-fifths of the ocean floor exceeds one mile in depth and has a temperature colder than 30C., it is of importance to know if bacteria and kindred microorganisms survive and if they are physiologically functional under such conditions. Our knowledge of the activities of bacteria in the sea is very fragmentary, but the few investigations which have been made indicate that bacteria probably play an important role in the sea. They themselves are consumed as food by many small marine animals and, also, by their activities they produce plant nutrients. They are the responsible agents for many of the chemical and physico-chemical changes which occur in sea water or on the ocean bottom, and they may be of geological importance (cf. Bavendamm, I93z); Benecke, I933; Waksman, I934). Experimental evidence indicates that for practical purposes the hydrostatic pressure of deep water is not inimical to microbial well-being. Tremendous pressures are encountered on the sea bottom but bacteria have been shown to tolerate far greater pressures than occur even in the most abyssal depths. Chlopin and Tammann (I903) found that pressures up to about Zgoo atmospheres, or approximaitely three times that found in the ocean, failed to harm bacteria, yeasts or molds, although individual organisms differed greatly in their susceptibilities to higher pressures. In the experiments of Larsen, Hartzell, and Diehl (I9I8), non-spore-formers survived at 3000 to 6ooo atmospheres and then, at these pressures, compressed gases, such as carbon dioxide, or the sudden release of pressure were found to be more detrimental than pressure itself. The actual recovery of bacteria by Certes