Wells – Processes – With indicating – testing – measuring or locating
Reexamination Certificate
2002-11-18
2004-04-27
Suchfield, George (Department: 3672)
Wells
Processes
With indicating, testing, measuring or locating
C073S152420, C166S250100, C175S042000, C436S027000, C436S029000, C507S267000, C507S271000, C507S272000, C507S907000, C507S924000
Reexamination Certificate
active
06725926
ABSTRACT:
BACKGROUND
The present embodiment relates generally to the recovery of hydrocarbons from a subterranean formation penetrated by a well bore and more particularly to non-radioactive compositions and methods of utilizing the non-radioactive compositions for determining the source of treatment fluids being produced from a production formation having multiple zones. For example, the compositions and methods can be utilized for tracking the transport of particulate solids during the production of hydrocarbons from a subterranean formation penetrated by a well bore.
Transport of particulate solids during the production of hydrocarbons from a subterranean formation penetrated by a well bore is a continuing problem. The transported solids can erode or cause significant wear in the hydrocarbon production equipment used in the recovery process. The solids also can clog or plug the well bore thereby limiting or completely stopping fluid production. Further, the transported particulates must be separated from the recovered hydrocarbons adding further expense to the processing. The particulates which are available for transport may be present due to an unconsolidated nature of a subterranean formation and/or as a result of well treatments placing particulates in a well bore or formation, such as, by gravel packing or propped fracturing.
In the treatment of subterranean formations, it is common to place particulate materials as a filter medium and/or a proppant in the near well bore area and in fractures extending outwardly from the well bore. In fracturing operations, proppant is carried into fractures created when hydraulic pressure is applied to these subterranean rock formations to a point where fractures are developed. Proppant suspended in a viscosified fracturing fluid is carried outwardly away from the well bore within the fractures as they are created and extended with continued pumping. Upon release of pumping pressure, the proppant materials remain in the fractures holding the separated rock faces in an open position forming a channel for flow of formation fluids back to the well bore.
Proppant flowback is the transport of proppants back into the well bore with the production of formation fluids following fracturing. This undesirable result causes undue wear on production equipment, the need for separation of solids from the produced hydrocarbons and occasionally also decreases the efficiency of the fracturing operation since the proppant does not remain within the fracture and may limit the width or conductivity of the created flow channel.
Current techniques for controlling the flowback of proppants include coating the proppants with curable resin, or blending the proppants with fibrous materials, tackifying agents or deformable particulates (See e.g. U.S. Pat. No. 6,328,105 to Betzold, U.S. Pat. No. 6,172,011 to Card et al. and U.S. Pat. No. 6,047,772 to Weaver et al.) For a multi-zone well that has been fractured with proppant and is plagued with proppant flowback problems, it is quite difficult to identify the zone from which the proppant is emanating unless the proppant is tagged with a tracer. Radioactive materials have been commonly used in the logging or tagging of sand or proppant placement, however, such radioactive materials are hazardous to the environment and the techniques for utilizing such radioactive materials are complex, expensive and time consuming. Therefore, there is a need for simple compositions and methods for tracking the flowback of proppant in subterranean wells to avoid the above problems.
DETAILED DESCRIPTION
According to one embodiment, to determine from which zone(s) a fluid is being produced, a water soluble inorganic or organic salt is dissolved in the base treatment fluid as the fluid is being pumped downhole during the treatment. Such treatment fluids include but are not limited to fracturing fluids, drilling fluids, disposal fluids and injection fluids used as displacement fluids in hydrocarbon recovery processes. Acting as a fluid tracer agent, a salt is tagged into the fluid that is unique for each treatment job such as a fracturing job treatment. Suitable water soluble salts for this purpose are metal salts in which the metal is selected from Groups Ito VIII of the Periodic Table of the Elements as well as the lanthanide series of rare earth metals so long as the metal salts do not constitute a component of fluids naturally present in the formation and are compatible with the fluids injected into the formation. Preferred metals include barium, beryllium, cadmium, chromium, cesium, sodium, potassium, manganese and zinc. Particularly preferred water soluble salts include barium bromide, barium iodide, beryllium fluoride, beryllium bromide, beryllium chloride, cadmium bromide, cadmium chloride, cadmium iodide, cadmium nitrate, chromium bromide, chromium chloride, chromium iodide, cesium bromide, cesium chloride, sodium bromide, sodium iodide, sodium nitrate, sodium nitrite, potassium iodide, potassium nitrate, manganese bromide, manganese chloride, zinc bromide, zinc chloride, zinc iodide, sodium monofluoroacetate, sodium trifluoroacetate, sodium 3-fluoropropionate, potassium monofluoroacetate, potassium trifluoroacetate, potassium 3-fluoropropionate.
The fluid tracer agents used in the method of this embodiment must meet a number of requirements. They should be relatively inexpensive, must be compatible with fluids naturally present in the reservoir and within the rock itself, as well as be compatible with the fluids injected into the reservoir as part of the formation treatment. The fluid tracer agents must be susceptible to being readily detected qualitatively and analyzed quantitatively in the presence of the materials naturally occurring in the formation fluids. For example, an aqueous sodium chloride solution could be utilized as a fluid tracer agent but for the fact that most field brines contain sodium chloride in substantial quantities, and so detection and analysis to differentiate the presence of sodium chloride used as tracer in the presence of naturally-occurring sodium chloride would be difficult.
In field application, a known amount of a selected water soluble salt based on a known concentration (i.e. 100 parts per million) is dissolved in a volume of water which is 1/1,000 of the total actual volume of base fluid required for the treatment. The mixed solution is then metered to the base fluid line at a rate of one gallon per 1,000 gallons of the base fluid. To handle multiple zones, various salts can be used provided that the interest cations or anions of selected compounds are unique to prevent any interference between zones.
According to another embodiment, metals are tagged onto proppant material or materials to be blended with proppant material to provide for the ready identification of flowback proppant from different stages or zones of the well. Suitable metals for this purpose may be selected from Groups Ito VIII of the Periodic Table of the elements as well as the lanthanide series of rare earth metals so long as the metals do not constitute a component of the proppant, the fracturing fluid or the reservoir fluid and so long as the metals are compatible with the fracturing fluid. Preferred metals include gold, silver, copper, aluminum, barium, beryllium, cadmium, cobalt, chromium, iron, lithium, magnesium, manganese, molybdenum, nickel, phosphorus, lead, titanium, vanadium and zinc as well as derivatives thereof including oxides, phosphates, sulfates, carbonates and salts thereof so long as such derivatives are only slightly soluble in water so that they remain intact during transport with the proppant from the surface into the fractures. Particularly preferred metals include copper, nickel, zinc, cadmium, magnesium and barium. The metal acts as a tracer material and a different metal is tagged onto the proppant, or onto the materials to be blended with the proppant, so that each proppant stage or each fracturing job treatment can be identified by a unique tracer material. Suitable metals for use as the tracer materia
Barton Johnny A.
Nguyen Philip D.
Weaver Jimmie D.
Halliburton Energy Service,s Inc.
Kent Robert A.
Kice Warren B.
Suchfield George
LandOfFree
Method of tracking fluids produced from various zones in... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of tracking fluids produced from various zones in..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of tracking fluids produced from various zones in... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3263765