The Hardware of Steam Injection

Bleakley, W.B. (The Oil and Gas Journal )


ABSTRACT Successes with steam injection as a means of increasing recovery from certain types of oil reservoirs have brought an entirely new line of equipment to the oil fields. This paper discusses operating principles and characteristics of equipment needed to carry out an oilfield steaming program, except for the steam generator. Water-treating and handling equipment, flow lines, well heads, down-hole tools, and accessory items are covered. INTRODUCTION Whether oil production is stimulated through the steam-soak (huff-and-puff) method or by well-to-well steam drive, there is more to the operation than just putting steam into the ground. Careful engineering of all phases of the operation is needed to avoid physical damage to surface equipment and injection wells, and chemical and mechanical damage to the reservoir Proper selection and application of equipment is one of the first steps in this careful engineering design, which covers the full range of operations from water treatment on the surface to injection of steam into the reservoir many feet underground. WATER TREATMENT Two major differences between industrials team boilers and oil-field steam generators dictate the differences in feed-water treatment, Fig 1. Conventional industrial steam systems usually operate oil a closed cycle in which steam used for turbine operation, heating of buildings, etc is returned to the holler for conversion to steam again Oil-field steamers operate on a "once-through" basis, where all steam generated is injected into the reservoir, and never recycled. Only a small amount of makeup water is needed to replace that which is accidentally lost from a conventional boiler system, or that which is used to "blow down" the boiler but feed water for an oil-field steam generator must be continuously replaced on a 100-percent basis. Cost of water treatment for a conventional boiler system, on a unit basis, is not too important because of the small number of 'units involved, but this same cost might be prohibitive in the oil fields. Conventional steam boilers take the steam to the dry saturated condition, or into the super-heat region, whereas oil-field steam is "wet" - generally about 80-percent quality (80-percent in the vapor phase, 20-percent in the liquid phase). The first of these differences is a disadvantage; the second is a distinct advantage The water-handling portion of a steam-injection system involves filtration, chemical treatment, storage, deaeration, conversion to steam, separation (optional), and metering (Fig 2) A description of equipment needed to treat feed water for oil-field steamers is impossible without some discussion of water-conditioning fundamentals, but no attempt will be made to cover the subject in detail as this has been clone adequately in recent publications Filters Feed water should be free of excessive suspended matter (non-ionic solids) to prevent contamination of subsequent treating equipment and plugging of parts of the system, including the sand face of the injection well Fig. 1 - Oil-field Steam-generating ProceduresRequire Unique Water-treatment (Available in full paper) Fig. 2 - Basic Components of a Steam-injection System, to the Well Head(Available in full paper)

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