Abstract: Reversible crosslinked polymer gels are prepared by adding a degelling agent precursor to a gelation solution during initial preparation. The precursor is integrated into the resulting gel and undergoes hydrolysis to transform into an active degelling agent which reverses the gel. The process has specific utility to hydrocarbon recovery applications where in situ gels are difficult to contact with conventional reversing agents.

Abstract: The present invention is a process for selectively plugging high permeability zones of a subterranean hydrocarbon-bearing formation by enhancing the delay associated with the in situ formation of a polymer gel. The process comprises predetermining a gelation delay time based on a formation's temperature, permeability and porosity, the distance from the well bore a region to be plugged is located, and a volumetric rate of gelation fluid injection. A gelation solution is then prepared comprising polyacrylamide a polyvalent metal carboxylate crosslinking agent, a gelation delaying agent and a buffer with a pKa of about 3.5 to about 6.8. Gelation delays are achieved by selecting the polyacrylamide concentration, delaying agent concentration and type, and buffer concentration and type, for given formation conditions. Delay times can range from several hours to several weeks at formation temperatures near 176.degree. F. (80.degree. C.

Abstract: Selective permeability reduction is achieved in a heterogeneous treatment zone of a subterranean hydrocarbon-bearing formation by initially placing a nonselective permeability-reducing material in the high and low permeability regions of the treatment zone. Thereafter, a permeability-restoring agent is placed in the regions behind the permeability-reducing material. The agent contacts all of the material in the low permeability region, reacting with it to restore permeability thereto. However, the agent is consumed by reaction before it contacts all of the material in the high permeability region, thereby leaving a sufficient amount of material in the high permeability region to achieve selective permeability reduction therein.

Abstract: The water content of a crude oil containing surfactant is reduced to less than 0.5 weight percent by first conventionally drying the crude oil to a water concentration less than about 10%, then contacting the crude oil with a low molecular weight alcohol to effect a phase separation into an aqueous layer and an oil layer, thereafter separating these layers to obtain a dried oil and an aqueous alcoholic surfactant solution. The alcohol can then be separated from the aqueous alcoholic surfactant solution. The recovered alcohol can be recycled through the system and the recovered surfactant can be reused in another micellar flood.

Abstract: The efficiency of pumping a hydrocarbon slurry in a pipeline is determined prior to transportation by the relationship:.DELTA.P=ae.sup.bXwherein .DELTA.P is the pressure drop expected to be experienced by the slurry in the pipeline in pounds per square inch (psi), "a" and "b" are constants relating to the size of the pipeline, the flow rate of the slurry and the hydrodynamic volume of the wax crystals, and "X" is the wax crystal content in the slurry from the congealed particles in percentage by weight. The wax crystal content of the slurry is measured, such as by nuclear magnetic resonance and/or differential scanning calorimetry, and is used in conjunction with the constants "a" and "b" to determine the expected pressure drop of the slurry in a particular pipeline. The wax crystal content of the slurry may then be modified, if necessary, to obtain desirable or optimum slurry pumpability conditions for the pipeline.

Abstract: The efficiency of a hydrocarbon slurry is maximized by determining the largest percent of economically pumpable distillation overhead that can be obtained from the hydrocarbon. This determination is based on the properties of the overhead as a carrier fluid in the transporting system (e.g. slurry viscosity or pumpability). Once determined, the composition of the optimum overhead is determined by the usual techniques, i.e., by gas chromatographic techniques, to determine its composition and the cut point defined in terms of the composition of the optimum overhead. The composition of the overhead is monitored during the refining process and is compared with the composition of the optimum overhead. The distillation process is then monitored and controlled accordingly to produce an overhead with the desired molecular composition. One advantage of this method is that it limits the amount of undesirable wax crystals in the overhead.