Down-hole pumping

At sites where the fluid level (water or LNAPL) is below the suction-lift depth, the use of a down-hole pumping unit is necessary. When a single-pump system is used, the water and/or LNAPL is delivered to the surface for separation or treatment, as shown in Figure 7.12. Several types of single-pump systems are in common usage. 

Fig. 2 shows indicator diagrams for wells operated by down-hole pumps in late production stage of the oil field. 

Equipment submerged in liquids, e.g. sump pumps, down-hole pumps. 

An important area where variable speed is used is in the drilling of wells where accurate control of speed and torque is essential. In recent years some attention has been focused on the application of variable speed motors in the down-hole pumping of oil, as discussed in sub-section 14.4.2. 

Down hole pumps, compact heat exchangers, rotating and in-line separators are already in use. In particular, the drive to improve physical separations and reduce size and cost has lead to the use of some intensified equipment. There is use of rotating separation equipment in the UK offshore sectors, but again overseas, notably China as already mentioned, leads the way both offshore and onshore. 

Beam pumping and electric submersible pumps (ESP) require a source of power. On land it may be convenient to tap into the local electricity network, or in the case of the beam pump to use a diesel powered engine. Offshore (ESP only) provision for power generation must be made to drive down hole electric pumps. 

Sandia Laboratories (Albuquerque) has recently completed a study on closed-cycle hydride engines based on the hydride chemical compression cycle (13) A practical demonstration unit was constructed to operate a water pump (lU). The down-hole bladder pump is capable of pumping against large hydrostatic heads. Coupled with a solar collection, this concept should find applications in arid third world countries. 

Because of its excellent chemical resistance, ETFE is used in the chemical industry for valve components, packings, pump impellers, laboratory ware, and battery and instrument components and for oil well, down-hole cables 41 Examples of such applications are shown in Figures 4.17 and 4.18. 

The terms EOR and lOR should refer to reservoir processes. Any practices that are independent of the recovery process itself should not be grouped into either EOR or lOR. Such practices include reservoir characterization, reservoir simulation, use of hardware and equipment (pumps, down-hole separators, etc.), use of special well types (horizontal wells, multilaterals, smart wells, etc.), improved reservoir management, infill drilling, and so on. Oil here means hydrocarbon, including oil and natural gas. 

Lithium-thionyl chloride (Li/SOCl2) cells have seen a number of uses, including remote monitoring (such as residential water meters), various OEM (original equipment manufacturer) electronic devices, military, aerospace, and down-hole oil well monitoring applications. Medical device uses have included implantable heart mmiitors, drug infusion pumps, and some of the earliest implantable cardiac pacemakers [9, 10]. 

Oil well cements are required to fix steel casing to the drilled borehole wall, for down-hole repairs and to isolate zones in the formation. Set retarders are required to prevent premature setting while the cement is being pumped into place through high-temperature zones. In this application, borates are used as set retarders or assists for other retarders, such as lignosul-fonates, cellulosic derivatives, and synthetic polymers. They are effective retarders for OPC and other cements. 

In rod-pumped wells, abrasion of rods on tubing adds the requirement that the inhibitor film have some lubricating properties. In many wells entry of air through the annulus requires that the inhibitor function in the presence of oxygen. Down-hole centrifugal pumps are susceptible to failure due to scaUng, and to velocity effects. 

Squeeze treatments are made by mixing the selected inhibitor in oil, aromatic solvent, or water at the proper ratio, which is determined by inhibitor fall out. The inhibitor may not be totally soluble in the diluent, but must be dispersible enough to be carried by the fluid into the tubing and down hole. The mix is pumped into the tubing and displaced to the bottom, followed by sufficient fluid to... 

In some cases, down-hole injectors are used these are generally located in the packer. The annulus is loaded with the inhibited fluid and pumped in at the surface at the desired rate. The pump must have a sufficient output pressure to overcome the down-hole pressure (taking into consideration the hydrostatic head) to open the injector. 

Hole Drilling. Hole drilling is another popular way of using ECM. As indicated in Eigure 3 a tubular electrode is used as the cathode tool. Electrolyte is pumped down the central bore of the tool, and out through the side gap formed between the wall of the tool and the hole electrolyticaHy dissolved in the workpiece (2,9,10). 

A vacuum system can be constmcted that includes a solar panel, ie, a leak-tight, instmmented vessel having a hole through which a gas vacuum pump operates. An approximate steady-state base pressure is estabUshed without test parts. It is assumed that the vessel with the test parts can be pumped down to the base pressure. The chamber is said to have an altitude potential corresponding to the height from the surface of the earth where the gas concentration is estimated to have the same approximate value as the base pressure of the clean, dry, and empty vacuum vessel. 

Hot water basins are used to distribute water in crossflow towers. Here, water is pumped to an open pan over the wet deck fill. The bottom of the pan has holes through which water is distributed. Manufacturers will fit specially shaped plastic drip orifices into the holes to give the water an umbrella shape for more uniform distribution. Different size orifices are used for different flow rates. Ideally, the basin will be almost full at maximum flow. This way, sufficient depth is retained for good water distribution as turn down occurs. The turn down ratio can be extended by the addition of hot water basin weirs- a pattern of baffles perhaps 2... 

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