Methane gas hydrates are cages of water molecule that trap small, low molecular weight gas molecules e.g. methane, ethane, hydrogen sulfide etc. the enormous quantity of gas stored in them (1m3 G.H = 180m3) makes them an important area of research for the scientist and petroleum engineers. Over the years the various theoretical techniques for recovery of the gas hydrates are 1.thermal injection 2.inhibitors 3.depressurization. However due to inefficient and economic unfeasibility it is difficult to recover the methane from gas hydrates. Low injectivity reservoir, small thickness of G.H bearing zone, heat loss especially in permafrost region, also the cost of the inhibitors (which change the thermodynamic condition) is litre of methanol makes it uneconomical, finally depressurization of an adjacent free gas zone can effectively dissociate hydrate but the endothermic nature of the hydrate decomposition will decrease the reservoir temperature and which may temporarily decrease the flow rate. The technical problems with estimating the gas hydrate areTechnology to safely and economically produce methane from G.H deposits.Safety and drill floor stability related issues related to drilling through G.H bearing accumulations. This paper deals with a new technique of a recovery of methane from G.H.This technique involves use of a micro strip antenna which has huge power gain and is relatively inexpensive, with wire line the tool is placed in well bore and frequency of 2450 MHz is released which melt the G.H into water and methyl radical (as they are almost similar to ice) such that they disturb the thermodynamic condition, then the fluorine is injected, this results in reaction between methyl radical and injected fluorine (halogenation), which is strongly exothermic (-431KJ/mole), this reaction propagates the reaction and simultaneously we have solubility of methyl fluoride with water which is 166cc/ 100 ml of water. This pressurized gas solution is then recovered via tubing from production well. Later by applying wurtz reaction, electrolysis and cracking methane can be recovered. The main advantage of using this technique is micro waves interact strongly with some materials and weakly with others, energy absorption depends on microwave frequency, sample composition, temperature. The chemical compound fluorine is abundant in nature (540000ppb) and methyl fluoride is environmental friendly. In this technique, the pressure of the fluids in contact with hydrate is lowered, pushing the hydrate out of its stability region and leading to its decomposition. Because no extra heat is introduced into the reservoir, the heat of decomposition must be supplied from the surrounding formation.
Methane gas hydrates are cages of water molecule that trap small, low molecular weight gas molecules e.g. methane, ethane, hydrogen sulfide etc. the enormous quantity of gas stored in them (1m 3 G.H = 180m 3 ) makes them an important area of research for the scientist and petroleum engineers.
CTU has been gaining importance in the oil industry. It is a multipurpose unit with one application being drilling. The major limitation of CTU was eliminated recently by inventing rotating coiled tubing which is yet to hit the commercial market. In this concept a conventional derrick based rig is modified to a Hybrid Drilling Rig. A coiled tubing unit is incorporated inside derrick structure itself at a height above the derrick floor which depends on type of derrick. The coiled tubing unit added is not the conventional one instead it is a unit that actually rotates the coiled tubing. This coiled tubing will be placed horizontally above the floor. It has a support structure passing through its center which is detachable. The use of this center structure is that it has straightening injector fixed in it and it supplies the torque to the CTU. Coiled tubing from the CTU will take a helical path around the support structure, pass through the injectors and become straight. The purpose of the paper is to discuss the advantages and limitations of this hybrid drilling rig technically and economically. Also some calculations are included which are used in the design of the rig used. This paper also outlines fatigue analysis and advantages and limitations of using rotating coiled tubing. Introduction CTU, after it was invented many decades ago has been experiencing increase in demand in the oil industry. Apart from its basic uses, it has recently gained importance for drilling. Hence with the advancement in coiled tubing drilling we can consider the CTU to be one of the most versatile equipment available to the industry that can be used for a wide range of jobs or tasks performed on the rig. The only problem with the coiled tubing was its inability to rotate which reduced its efficiency. Recently rotating coiled tubing was invented by John Van Way which was used on a workover rig as a model in Louisiana. This is the basis on which this concept, of using a CTU on a rig efficiently, may fetch us good results. This paper will give describe how a rotating coiled tubing can work on a rig. Now days whole vertical wells are drilled with coiled tubing especially in many parts of Canada but still it poses some problems when it comes to hard formations. Coiled tubing drilling is not a replacement of conventional drilling equipment for drilling conventional, directional, and horizontal wells. The real application will be on drilling projects requiring special consideration such as:Environmentally sensitive areas where noise abatement and well control must be assured.Underbalanced drilling in areas where special permission is required and may not be obtainable for conventional equipment. These projects may require oil based mud systems, or aerated or gasified mud systems.Offshore re-entry drilling where the platform cannot support a workover rig or workover rig does not exist and would be too costly to refit platform with a rig.Through tubing drilling where mobilizing a workover rig to pull the production tubing would increase project cost to the point that would be uneconomical.High pressure underbalanced drilling where conditions exceed normal equipment capabilities. So drilling with this hybrid rig requires use of the conventional rotary steerable drilling technique and reduce the costs by using coiled tubing simultaneously wherever possible, making it an overall economical drilling project. Besides coiled tubing will provide its conventional services like well unloading, cleanouts, acidizing/stimulation, velocity strings, fishing, tool conveyance, well logging (real time & memory), setting/retrieving plugs and fracturing onboard.
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