Patent Application
20070295644
A detailed description of preferred embodiments of the invention follows, with reference to the attached drawings, wherein:
The invention relates to improvement of heavy hydrocarbons and, more particularly, to a process and system for recovering and upgrading heavy hydrocarbons which is economical and effective, and which can be used, for example, to recover and upgrade hydrocarbons from waste drilling fluid pits.
According to the invention, heavy and extra heavy hydrocarbons are recovered and upgraded by contacting with a solvent in a reactor at relatively mild conditions, and then separated to produce an upgraded hydrocarbon which can be useful for further processing and the like. One particularly preferred application of the present invention is in recovering such hydrocarbons from stored waste drilling fluids. Alternatively, the process of the present invention is also useful in producing upgraded hydrocarbon from tar and bituminous sands and the like. The process of the present invention is a de-asphalting process, and the solvent in such processes acts as a liquid-liquid extracting medium, facilitating the precipitation of asphaltene, water and sediments present in the waste hydrocarbon product.
As set forth above, one typical starting material for the process of the present invention is a waste drilling fluid. Such fluid typically contains hydrocarbons mixed and sometimes emulsified in with water, and contain various solids and other materials which complicate processing and use. Physical-chemical characteristics of a typical starting material are described in Table 1 below.
Other types of hydrocarbons can be upgraded within the broad scope of the present invention. For example, the process can also be used for upgrading and producing heavy and extra heavy hydrocarbons from subterranean reservoirs.
When the starting hydrocarbon is a waste drilling fluid, care is taken to ensure that any large waste material such as iron debris, logs, etc. are removed. These fluids initially can be pumped to a storage tank near the reactor using vacuum devices, or the system can be deployed near the waste fluid drilling pit. If the waste reservoir is semi-solid, transfer can be done using mechanical arms such as a pailover device to feed a storage tank, or directly to the reactor. Generally, most of these waste drilling pits are liquids with heavy densities that can be vacuum pumpted to the reactor zone.
As set forth above, the hydrocarbon starting material is upgraded by contacting with a comparatively light solvent, preferably a C2-C5 light petroleum fraction. Examples of preferred solvents include but are not limited to propane, liquid petroleum gas (LPG), liquid natural gas (LNG) and mixtures thereof. These are refinery gases, which can readily be obtained from gas and petroleum wells.
According to the invention, solvent and starting hydrocarbon material are contacted in a reactor, and exposed in the reactor to conditions which lead to upgrading of the hydrocarbon. Preferred processing conditions include a temperature of between about 300 and about 1000, and a pressure of between about 100 psig and about 350 psig. The processing time varies depending upon the nature of the hydrocarbon starting material, and is typically between 10 and 60 minutes, if the reaction is continuous; and between 30 and 1,440 minutes if the reaction is done in batch. As will be discussed below, the process can preferably be carried out in a continuous fashion, and therefore the reaction time can appropriately be given in terms of residence time within the reactor.
Numerous different reactors can be used to produce the upgrading conditions as set forth above. Further, while the vessel in which the contacting takes place is called a reactor, there are numerous different types of equipment with which the reaction can carried out, and these other types of equipment are intended to be included broadly within the term reactor. For example, the process can be conducted utilizing a mixer having either mechanical mixing parts, or gas flow mixers, or both, or can be a flow mixer with or without mechanical mixing. Alternatively, the reactor can be a gravity or cyclonic settler, or a centrifugal sedimenter or the like.
Mixer-sedimenter type reactors are preferred because they provide for mechanical mixing without risk of flooding, and also because they help to avoid the formation of stable emulsions. Such a reactor is a closed receptacle which has mechanical agitation and sedimentation by gravity and/or centrifuge.
In a batch process, both mixing and sedimentation can be carried out in the same reactor. In this instance, the reactor can be modified in order to accommodate various accessories to improve efficiency.
When the process is carried out as a continuous process, these steps can be carried out sequentially.
After the contacting step, two distinct products or product streams are produced out of the reactor. A first product or product stream is a mixture of upgraded hydrocarbon and solvent. A second product or product stream is made up of asphaltene waste, water and solvent.
The first product, containing upgraded hydrocarbon and solvent, is preferably fed to a separator to produce a final upgraded hydrocarbon product and recycled solvent. The upgraded product can be fed to a storage tank or directly to further processing as desired. The solvent can suitable be recycled back to the beginning of the process, for example through a compressor or the like.
The second product, containing asphaltene waste, water and solvent, can also be fed to a separator to separate into three products or product streams, including asphaltene, water and solvent.
The first product is typically discharged from the upper outlet of the reactor, while the second product is typically discharged through the lower outlet of the reactor.
The solvent is preferably fed to the same recycling stream as the separated solvent from the first product. The asphaltene waste is preferable stored in a suitable storage vessel or tank. This material can advantageously be utilized in road building or repair. Soil and other sediments obtained through the process can also be used in various applications. Finally, the water component can be stored and/or treated and recycled to other processes or uses such as irrigating crops.
Solvent and hydrocarbon are preferably contacted under a controlled weight ratio of hydrocarbon to solvent, which can advantageously be between about 1:1 and about 1:3. As will be illustrated with the examples below, different results are obtained using different ratios of hydrocarbon to solvent. Further, different solvents direct the reaction in different manners, and therefore it is desirable to select the suitable solvent based upon the results desired.
The separators used to treat the first and second products can be conventional vertical systems for gas-liquid separation, or can be other types of separator as well, for example, such as cyclonic and/or centrifugal separators.
Contacting step 12 produces a hydrocarbon and solvent stream or product through one outlet 25 to line 26 and an asphaltene waste, water and solvent stream or product through another outlet 27 to line 28. Line 26 leads to a first separator illustrated at step 14 and having two outlets 30, 32. Line 28 leads to a second separator illustrated at step 16 and having three outlets 34, 36, 38.
Outlet 30 carries solvent from separator 14 to line 40 to compressor 24. Outlet 32 carries a separated and improved or upgraded hydrocarbon to line 42 to storage tank 18.
Outlet 34 carries separated solvent from separator 16 to line 44 to compressor 24. Outlet 36 carries asphaltene waste from separator 16 through line 46 to storage tank 20. Outlet 38 carries separated water through line 48 to storage tank 22.
Compressor 24 feeds solvent back to the reactor for contacting step 12, through line 50, with or without solvent makeup from solvent source 52.
The hydrocarbon feed to the reactor for contacting step 12 is schematically illustrated as 54 in
Thus, the system illustrated can be transported in modular form to various locations of interest, for example the site of a waste fluid pit, or a well drilled into a subterranean tar sand formation, and can be used to produce the upgraded hydrocarbon, water, and asphaltene products, starting only with the starting hydrocarbon material and a source of light solvent.
Alternatively, these components can be assembled into a permanent facility and waste fluid transported to that facility. The reactor and separators are all equipment which is readily available and known to a person of skill in the art. The storage tanks can be any suitable vessel for storing the product to be stored, and would also be known to a person skilled in the art.
This example demonstrates the process for upgrading a hydrocarbon contained in a hydrocarbon waste fluid mixture from drilling cut waste fluids pits from Eastern Venezuela. This waste fluid mixture has an experimentally measured API gravity of 11.
A sample of approximately 100 g of the mixture was placed in a reactor chamber in ratios of hydrocarbon mixture to solvent (LNG) of 1:1, 1:2 and 1:3 w/w. The amount of solvent used was determined based upon an effective weight of the hydrocarbon after removal from the pit. The reactor was a piston-cylinder type. The contact time between the hydrocarbon mixture and the solvent was set at 48 hrs, at a pressure of 300 psig and a temperature of 60° C. This process was a batch type process.
After the reaction time was reached, the hydrocarbon-solvent fraction from the reactor was sent to a separator through the top outlet of the reactor. Additionally, the bottoms mixture of water, sediment, solvent and asphalting fraction was discharged through the bottom outlet of the reactor. This procedure was repeated four times for each hydrocarbon mixture:solvent ratio. The average results of these procedures are shown in Table 2.
From the experimental results obtained, the following observations are of interest. First, in all the weight ratios employed (1:1, 1:2, and 1:3), an improvement of the waste hydrocarbon mixture is demonstrated by the increase in API gravity. This gravity increases by 16, 23 and 29 degrees for ratios of 1:1, 1:2 and 1:3, respectively. Second, with increased amounts of solvent, better percentage improvement of the hydrocarbon fraction product is obtained. Third, with increased amounts of solvent, the amount of asphaltene residues produced is lower (See
In addition to the increase in API gravity; there is a noticeable reduction in the content of asphaltene, vanadium, nickel, iron and sulfur. Table 3 shows the results for this example for the sample where the ratio was 1:1.
In this example a mixture of hydrocarbon waste fluid from a waste pit from the Western part of Venezuela was used. The initial API gravity was 11, and the sample contained 14.6-15% water and sediments (% w/s). The hydrocarbon mixture was evaluated using LNG as solvent, and also using propane as solvent, using exactly the same weight to weight ratios as set forth in Example 1. The contact/reaction time was set at 48 hours under a pressure of 300 psig and a temperature of 60° C.
After the reaction time was reached, the separation process was performed as in Example 1. Through the bottom, a solid mixture (asphaltene, sediment, water and some solvent) was discharged. From the top, a recuperated and improved hydrocarbon fraction together with most of the solvent was discharged. After further separation, the final upgraded product was obtained and evaluated, and the results are set forth in Table 4.
As indicated in Table 4, API gravity has increased in both runs, using LNG and propane, as compared to the initially calculated API gravity of the hydrocarbon mixture from the drilling cut waste pit from Western Venezuela. This increase in API gravity was between about 10 to about 16 degrees. There is a difference in the percentage of hydrocarbon recovered from the waste mixture depending upon the solvent. Specifically, LNG offers better recovery than propane. One advantage of using propane, however, is the higher selectivity for extracting light hydrocarbon components from the waste hydrocarbon mixture.
This example demonstrates the use of the present invention for improvement of a hydrocarbon residue from a distillation process, at 400° C., of a hydrocarbon with API gravity of 16. The residue had a starting API gravity of 8. The Example also provides an example for improvement of an extra heavy hydrocarbon (8° API) from the Venezuelan Orinoco Oil Belt. For this example, the sample was taken directly from the formation. In both cases, the experimental process was carried out using LNG as solvent, using a 1:1 w/w ratio of hydrocarbon to solvent. The deasphalting process conditions were a pressure of 300 psig and a temperature of 60° C., for a time period of 48 hours, in a batch reactor. The results are as set forth in Table 5.
As observed in Table 5, for the hydrocarbon residue coming from the distillation unit, an improvement in API gravity is observed, increasing from 8 to 26.6° API, with a product yield of about 63%. In the second case, with a sample directly from the formation, extra heavy hydrocarbon from the Orinoco Oil Belt region, is improved in API gravity from 8 to 24 with a product yield of 89% weight product.
This example demonstrates the improvement, dehydration and desalting of an extra heavy hydrocarbon from Western Venezuela (8° API) in the form of an emulsion with salty water (22% water content in a W/O emulsion). The initial mixture contained a 1 to 1 ratio of extra heavy hydrocarbon to LNG under the conditions used in Example 1. The results are shown in Table 6.
Table 6 shows a great increase in API gravity, from 8 to 21.6, for the improved hydrocarbon product. Additionally, the salt content in the improved hydrocarbon, in pounds per thousand barrel (PTB), drops drastically to less than 1 PTB, indicating excellent desalting. The water content in the improved hydrocarbon also dropped to nearly zero, indicating a complete dehydration of the starting HC/W emulsion.
The above Examples show that the process of the present invention meets the objectives set forth, and provides for recovery and upgrading of hydrocarbons from waste drilling fluids for example stored in drilling cut pits. Further, the process of the present invention produces these results while also producing water for agricultural use, apshaltene products for road building and repair, and soil/sedimentation which can also be used in agricultural applications. The process provides a substantial increase in API gravity and an excellent yield rate. Further, the hydrocarbon also shows excellent reduction in various other undesirable components. Thus, the process and system of the present invention advantageously solve the problems set forth above.
It is to be understood that the invention is not limited to the illustrations described and shown herein, which are deemed to be merely illustrative of the best modes of carrying out the invention, and which are susceptible of modification of form, size, arrangement of parts and details of operation. The invention rather is intended to encompass all such modifications which are within its spirit and scope as defined by the claims.
This application claims the benefit of the filing date of provisional application No. 60/817,030, filed Jun. 27, 2006.
| Number | Date | Country | |
|---|---|---|---|
| 60817030 | Jun 2006 | US |
