Crude oil systems

Medium Oil systems, crude oil distillation, absorbers, midpressure (100-300 psia) hydrocarbons 03-0.4 0.4-0.5 04-0.5°... 

Far from a wellbore, the velocity of reservoir fluids is about one linear foot per day. Near a wellbore, the velocity can increase one-hundred fold. A static or quasi-static test such as the sessile drop (contact angle) test may not represent the dynamic behavior of the fluids in the field. The dynamic Wilhelmy device gives results which are comparable in interface velocity to the field displacement rate. The interface in the Wilhelmy test described here moved at a steady rate of 0.127 mm/sec or 36 ft/day. The wetting cycle for a hybrid-wetting crude oil system was not affected by moving at a rate less than 1 ft/day. 

The carbon footprint of transport fuels has been analyzed in several studies starting from 1990. One of the most important is the study realized by Sheehan et al. [13] at National Renewable Energy Laboratory of the United States.This is an LCA study that includes the impact of C02 emissions. Most important operations belonging to the petroleum diesel product system include crude oil extraction, its transport to an oil refinery, crude oil refining to diesel fuel, its transportation to the user, and its use in a bus engine. 

Katz, D.L. and Firoozabadi, A. Predicting Phase Behavior of Condensate/Crude-Oil Systems Using Methane Interaction Coefficients, Trans., AIME (1978) 265, 1649-1655. 

Ng, J.T.H. and Egbogah, E.O. An Improved Temperature-Viscosity Correlation for Crude Oil Systems, paper 83-34-32 presented at Petroleum Society of CIM 34th Annual Technical Meeting, Banff, May 10-13, 1983. 

Tn this work the sulfur compounds in the gas oil of three Cretaceous - heavy oils from the edge of the Alberta sedimentary basin were investigated. These crude oils were obtained from the Athabasca, Cold Lake, and Lloydminster deposits and are believed (I) to belong to the same oil system which implies like modes of origin. The geographic location of these deposits is shown in Figure 1. This investigation was conducted to develop the analytical capability used to follow the maturation of the sulfur compounds in these oils (2). 

Table 1. Film Parameters for C.AOS/Salem Crude Oil System at 1% NaCl...

Emulsification Properties of Crude Oils. Although impossible to predict with certainty which crude oil systems will easily emulsify to form stable 0/W emulsions, some general rules were observed to apply ... 

It should be pointed out that the gas solubility could be calculated using the laws of solution behavior previously described in Chapter 5, provided sufficient data are available. It is necessary to have not only data for the overall composition of the system hut complete and accurate equilibrium constant data as well. These data are seldom, if ever, available for a crude-oil system and values of gas solubility must be obtained either experimentally or by estimation. However, to illustrate the complexity of computations of this type the method is outlined below for a two-component system of known overall composition. 

In a batch degumming system, crude soybean oil is typically heated to about 70°C in a large tank htted with an agitator. Water is added (about 2% by volume), and the hydrated oil is agitated for up to one hour. The hydration of soybean... 

In extreme cases, material can adsorb at an interface to create a film. Interfacial film formation can occur in crude-oil systems and has been reported by Blair (16), and by Reisberg and Doscher (17), Film formation is relatively common with crude oils and can effectively stabilize emulsions by preventing droplet coalescence even with high values of interfacial tension. 

Emulsions stabilized by paraffin are usually restricted to light crude oils in oil-field production. If paraffin deposition that restricts production is occurring upstream of an oil-treating facility, it may be feasible to apply a paraffin crystal modifier to the crude oil to prevent paraffin deposition and to eliminate paraffin as an emulsifying agent. A paraffin crystal modifier must enter an oil system at a temperature greater than the cloud point of the crude oil and upstream of the problem area. 

Synthetic crude oil is the hydrocarbon liquid that is produced from bitumen, by a variety of processes that involve thermal decomposition. Synthetic crude oil (also referred to as syncrude) is a marketable and transportable product that resembles conventional crude oil. Synthetic crude oil, although it may be produced from one of the less conventional fossil fuel sources, can be accepted into and refined by the usual refinery system. 

Figure 5 shows the kinetics of coalescence for the caustic (0.05M NaOH, 1.0% NaCl), Thums Long Beach (heavy) crude oil system, with and without the co-surfactant n-hexanol (0.5%). This data shows that the mean droplet volume (which is proportional to 1/number of droplets) increases with time. The addition of hexanol alters the kinetics of interdroplet coalescence to a level that the emulsion almost totally coalesces within ten days. 

The interfacial tension values reported for the caustic system in Figure 8 are comparable to the values reported recently in reference (22). Our experiments which have been conducted at a room temperature of about 25°C show that 0.1 to 0.4 weight percent concentrations of NaOH and 1.00 weight percent NaCl can lower the interfacial tension between the aqueous solution and the crude oil substantially below a value of 0.01 dynes/cm or that required for emulsification. We have previously discussed the stability of these emulsions (Fig. 5). In the experiments run on fired Berea cores, it was reported that a concentration of 0.1% NaOH and 1% NaCl in the caustic crude oil system resulted in a drastic reduction in residual oil saturation. The details of these tests are given in reference (22). 

When an aqueous system containing a surfactant, cosurfactant and of intermediate salinities is allowed to equilibrate with crude oil, the mixture sometimes separates into three phases. One of these phases is the aqueous phase which contains very little surfactant. This is called the lower phase. The second phase is called the middle phase. This phase is a microemulsion which contains large amounts of both oil and water and nearly all the surfactant. The third (upper) phase contains the oil. Systems of oil and aqueous phases which show this phase behavior are said to exist in the "beta" region of the phase diagram. The "beta" type systems have been shown to form the least stable emulsions and thereby result in enhanced oil recovery (30). 

Table VIII summarizes the investment and operating requirements for the H-Oil unit and its attendant facilities, and Table IX compares investment and operating costs for the naphtha and crude oil based facilities. Data on the ethylene plant investment and operating costs were taken from the paper by Freiling, Huson, and Tucker (I). Offsite investments have been taken at 30% of process investment for the naphtha case, as well as for the ethylene plant portion of the crude oil case. For the H-Oil unit and its associated units offsites have been estimated at one-half of this rate—15%. This lower value has been used since the H-Oil system will add little to the storage requirements, and all utilities have been priced to cover the capital requirements for their production.

---