Geology. Geophysics. Drilling
In domestic and foreign practice invert emulsion drilling fluids (EDI) get more widespread in well drilling and completion, which ensure successful well steering in complex geological conditions, where using of water-based muds do not allow incident-free drilling. The reason is, first of all, that the hydrocarbon phase is neutral respectively to passable rocks, including salts and clays.
Increasing of EDI using is defined by constantly increasing quality demands while opening of reservoirs which is the most important stage in the cycle of well construction. One of the particular difficulty is the opening of reservoirs with long horizontal wells, since the natural reservoir properties of the rocks decrease with depth increasing. Using water-based muds in such conditions leads to the deterioration of the permeability of bottomhole formation zone and the need for a large amount of work on the flow stimulation.
Primarily, IDE is used for opening of productive layers with the aim of preserving their reservoir properties, represented by salt deposits, and swelling clays and other rocks, losing stability when in contact with water-based solutions
This article discusses a number of shortcomings of EDI, such as high aggressiveness of dispersion medium, and a significant decrease in rheological properties associated with increasing temperature as well as methods for solving these problems.
Shale shakers are components drilling mud cleaning which used for purification of drilling mud fluid of particles cuttings well drilling. Shale shaker is the first stage of the process, purifies solution from 10 – 20% larger than the sludge 75-100 microns. Shale shakers are involved in the large part of the mud cleaning from cuttings, this most widespread means of purification of drilling mud fluid, so they should be given special attention.
This article presents the shale shakers classification according to the type of screens set, the type of oscillations and the number of cleaning levels.
In the process of shale shakers operation, like in case with any other equipment, failures occur. Failures caused by shale shaker work in quite difficult conditions: the cleaning solution contains many impurities that contribute to corrosion of metal, abrasive particles in solution, lead to hydroabrasive wear mesh, negative impact on the shale shaker has a vibration. An analysis of possible shale shakers failures has been conducted, on the basis of which the classification of failures has been developed.
The main directions for shale shakers improvement have been considered: the transition from flexible stretching screen cassetts to framed screen cassettes, general using of shale shakers as a part of mud cleaners and the improvement of mud cleaning efficiency by changing the type and frequency of oscillations.
The results of studies of samples reagent Methacrylate M14BB, Lakris and HBN-01 consisting of bentonite natural clay suspensions and drilling fluids used in the November oil and gas region of Western Siberia.
Reagents M14BB and Lakris in commercial dry clay are poorly soluble in the solution forming the polymer lumps. Supplement of these reagents have little effect on the reduction of the filtration rate of clay solutions. Reagent Lakris more effective for increasing the viscosity of the mud compared to the reagent M14BB. Polymers M14BB and Lakris can be recommended as thickeners bentonite slurry for drilling under the conductor. However, the input of reagents Lakris and M14BB in the presentation in the clay solution is undesirable, better to process in the form of an aqueous solution or an aqueous solution with the addition of alkali.
Polymer HBN-01 when added to drilling fluids leads to a significant improvement of structural and rheological properties and a slight decrease in the filtration rate. Reagent HBN-01 can also be recommended to improve the structural-rheological properties of clay drilling fluids used during well drilling under the conductor.
The chemical reagents M14BB, Lakris and HBN-01 can find limited application in flushing liquids for drilling under the production casing, for example in compositions with other reducers of the rate of filtration.
The article presents a review of own and published data on ore-bearing of mainly granitoid and ultrabasic massifs of the Bashkirian meganticlinorium, Zilair magasynclinorium, Uraltau meganticlinorium and the zone of the Main Uralian fault. It is shown that the greatest prospects for gold mineralization among the granitoid intrusions of the Bashkirian meganticlinorium has a framing of Akhmerovsky massif, which is part of the Beloretsky metamorphic complex, on the periphery of which in carbonaceous deposits revealed a number of gold manifestations. All of them are confined to the external high-temperature zone of green shale facies of metamorphism. Within Zilair megasynclinorium the largest and almost the only is the gabbro-ultrabasic intrusive complex, the most famous representative of which is Kraka massif with many small and individual fairly large of chromite objects. They are all associated with different-sized dunite bodies. In the southern part of the Middle Kraka massif in chromite ores and sulfidizing rocks of the banded dunite-clinopyroxenite complex established high (up to 3-5 g/t) content of precious metals.
Among the intrusive complexes of Uraltau meganticlinorium the most perspective are barangulovsky gabbro-granite-leucogranite with the tantalum-niobium mineralization; artlysh, in a frame of which marked the tungsten-molybdenum mineralization, and karyabinsky, containing of copper mineralization.
Numerous massifs of gabbro-ultrabasic intrusive complex, tracer of the Main Uralian fault, contain a series of chromite deposits and occurrences, sulphide copper-cobalt and copper-nickel ores, gold and PGE mineralization, including some rather large objects (Nailinsky, Tyelginsky, Ivanovo, etc.).