Abstract: Mixed dimer and mixed oligomer compositions are disclosed. The mixed dimer compositions comprise a monosulfonated cross-dimer or a salt thereof. The monosulfonated cross-dimer is a reaction product of (a) an alpha-olefin sulfonic acid (AOS acid); and (b) an unsulfonated olefin, an unsulfonated olefin precursor, or a functionalized olefin. The mixed oligomer compositions comprise a mono- or polysulfonated cross-oligomer or a salt thereof. The mono- or polysulfonated cross-oligomer is a reaction product of (a) an AOS acid; and (b) an unsulfonated diolefin or an unsulfonated diolefin precursor. Various methods for making the mixed dimer or oligomer compositions are described. Salts of the mixed dimer and oligomer compositions are useful surfactants for foams used in oilfield and other applications. The foams have improved high-temperature stability when compared with foams from AOS dimer acid salts.

Abstract: Methods of making an alpha-olefin sulfonic dimer acid (AOS dimer acid) are disclosed. In one method, an alpha-olefin is sulfonated, preferably with sulfur trioxide, to produce a mixture comprising an alpha-olefin sulfonic acid (AOS acid) and sulfur dioxide. This mixture is then heated while purging sulfur dioxide and hydrogen sulfide from the reactor to produce an AOS dimer acid composition. In another method, the AOS acid mixture is treated to remove sulfur dioxide and is then heated to produce an AOS dimer acid composition. With either method, the resulting AOS dimer acid composition has at least a 30% decrease in the level of elemental sulfur when compared with that of an AOS dimer acid composition prepared by a similar process in the absence of any active removal of sulfur dioxide or hydrogen sulfide. AOS dimer acid compositions and salts of the AOS dimer acids, which are useful surfactants for oilfield and other applications, are also disclosed.

Abstract: Methods for making efficient use of steam in a steam-assisted gravity drainage (SAGD) process for recovering heavy oils from tar sands and similar petroleum deposits are disclosed. The methods utilize a surfactant to generate steam foam in ways that maximize efficient use of steam. In some aspects, steam foam is used in water layers or gas caps that reside above steam chambers to prevent loss of steam from the steam chamber. The predominant use of relatively dry steam in SAGD processes makes it challenging to find ways to introduce surfactants and generate steam foam. However, decreasing the mobility of the steam by converting at least some of it to foam allows the wellbore and steam chambers above the injection site to be more fully developed, provides for more effective heat transfer to the heavy oil and rock, improves production, and allows recovery of the heavy oil with a minimum amount of steam usage.