Solids control methods

Many reservoirs are now being exploited by horizontal wells, which have long horizontal contact with the reservoir. Solids control methods for horizontal wells have been adapted from those used in vertical wells. Special techniques and equipment have been developed to remove deposited solids from horizontal wells. 

Prediction of Solids Production. In the development of conventional oil and gas reservoirs, solids management strategies are used to avoid solids production by proper production practices or to control or prevent solids production, if it is unavoidable. The use of solids control methods is usually based on experience with analogous offset wells in the area where a new well is to be drilled. Offset well data can be used effectively if the geological and reservoir characteristics and the well drilling, completion, and production procedures are similar. It is often difficult or expensive to recomplete wells if a solids production problem occurs after initial completion of the well. In some cases, productivity may be negatively impacted if solids control is retroactively installed in... 

Other Methods. Several other solids control methods have been used or proposed. An overbalanced resin surging method (85, 86) forces resin into perforations with an instantaneous release of overbalanced pressure. This method is used when a wellbore has existing perforations in an unconsolidated formation. Acid injection into the perforations converts the resin into a plastic that consolidates prepacked gravel or formation sand. 

The second method could be automatic intermittent blowdown. With this, a timer-controlled valve is installed at the bottom of the boiler prior to the main blowdown valve. A program is then designed to operate this valve in short bursts, which disperses any sludge and controls the levels of solids. This method is preferred for boilers having internal treatment. 

The most important nanomaterial synthesis methods include nanolithography techniques, template-directed syntheses, vapor-phase methods, vapor-liquid-solid (VLS) methods, solution-liquid-solid (SLS) approaches, sol-gel processes, micelle, vapor deposition, solvothermal methods, and pyrolysis methods [1, 2]. For many of these procedures, the control of size and shape, the flexibility in the materials that can be synthesized, and the potential for scaling up, are the main limitations. In general, the understanding of the growth mechanism of any as-... 

Sedimentation basins can be used to collect and store surface water flow and to settle suspended solid particles. Seepage basins and ditches can be used to discharge uncontaminated or treated water downgradient of the site. It is important to separate clean surface runoff from contaminated water and store and treat them separately. Table 16.4 summarizes the surface water control methods. 

Disposal of brine in subsurface wells is probably the most widely used control method, especially in the western and southern oil and gas producing states [23]. For this to be an effective disposal option, two conditions must be met the natural aquifer must be naturally saline and must not leak to freshwater aquifers, and the reinjection pressure must not exceed the fracture pressure of the formation [9]. Produced water is usually pretreated to prevent equipment from being corroded and to prevent plugging of the sand at the base of the well. Pretreatment may include the removal of oils and floating material, suspended solids, biological growth, dissolved gases, precipitable ions, acidity, or alkalinity [27]. A typical system is shown in Fig. 12. 

In order to obtain a reliable product, each fully protected segment must be carefully synthesized in solution. However, if homogeneity of the synthetic segments can be controlled properly, the synthesis can also be carried out by the solid-phase method. 

Fig. 5 shows control methods often used on vertical separators. The first is strictly level control. A regular displacer float is used to control the gas-oil interface and regulate a control valve dumping oil from the oil section. An interface float is used to control the oil-water interface and regulate a water oudet control valve. Because no internal baffling or weirs are used, this system is the easiest to fabricate and handles sand and solids production best. 

In the open literature (Ref 17) is briefly described a continuous, remotely controlled, method of mixing ingredients for composite proplnts, which was recently developed at the US Naval Propellant Plant, Indian Head, Maryland. The pilot plant installation at Indian Head, represented schematically in Fig, consists of a mixer B (which is a long cylindrical vessel in which a porous pipe C is inserted) a tube A for introducing into the mixer the solid and liq ingredients and a series of manifolds, M, serving for injection of air thru the pores in C... 

In Section V-D it was shown that Slurry sensitivity and performance depend on Slurry characteristics such as d, particle size of solids and compn, as well as external factors such as pressure and temp. To a considerable degree the effects of internal and external factors can be optimized by control of the rheology and d of Slurries. We shall now examine the rationale behind these control methods... 

The possibility to obtain a full solvent-free product, controlling in the same time the dimension of particles, is probably the most important feature when pharmaceutical substances are used. In the SAS process the SCF is used as the antisolvent. An organic solvent has to be involved in addition to the SCF and the solid solute. Basically, the process is performed by first dissolving the solid of interest in the organic liquid then, the SCF, which has low solvent capacity with respect to the solid but is completely miscible with the liquid, is added to the solution to get the precipitation of the solid. This method has been proposed by Gallagher and coworkers [8] to crystallize difficult-to-handle high explosives. Recently, other applications have been set forth to produce crystals of pharmaceuticals [9,10]. 

The progress in the development of improved monitoring techniques for the heterogeneous synthetic reactions involved in the solid phase method provided the feedback control which was necessary for the full automation of the peptide synthesizers. A monitoring system, which is based on the titration of the unreacted polymer-peptide chains with picric acid 34,35), on coupling with a peptide synthesizer provided an automatic feedback 36). This feedback is to implement the next step in the synthesis if the level of the unreacted peptide chains is below the acceptable preset value, or otherwise to repeat the last step. 

The solubilizing effect of PEG on the attached peptide and the absence of any direct influence of the polyoxyethylene chain on the physicochemical properties of the peptides provide a wider range of possibilities for analytical control during the liquid phase peptide synthesis than those in the solid phase method. The reactions employed in the stepwise liquid phase synthesis can thus be quantitatively monitored by several analytical methods. 

Fig. 7. Accuracy of the solid sample methods controlled by standard samples.

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