TRACER AND METHOD

Abstract

The invention concerns a tracer material for tracing fluid flows from a hydrocarbon reservoir. The tracer material comprises a plurality of separate agglomerates. The agglomerates comprise clusters of particles. The particles carry a tracer composition. A retaining material at least partially overlies the tracer composition. The retaining material retards the release of the tracer material so that the tracer is released at a more constant rate over a longer period than in the absence of the retaining material.

Claims

1. A tracer material comprising a plurality of separate agglomerates, each agglomerate comprising a cluster of particles, wherein the particles carry a tracer composition at least partially overlain by a retaining material and wherein the cluster of particles is bound together by a binding material so as to form the agglomerate.

2. A tracer material according to claim 1 wherein the particles have an outer surface on which the tracer composition is at least partially located and on which the retaining material at least partially overlies the composition.

3. A tracer material according to claim 1, wherein the particles are porous particles having at least some pores in which the tracer composition is at least partially located and in which the retaining material at least partially overlies the tracer composition.

4. A tracer material according to claim 1, wherein the binding material is the retaining material.

5. A tracer material according to claim 1, wherein the tracer composition contains one or more tracers for tracing hydrocarbon flow and one or more different tracers for tracing water flows.

6. A tracer material according to claim 1, wherein the tracer material includes a plurality of each of two or more different types of agglomerate, each type of agglomerate comprising a different tracer composition.

7. A tracer material according to claim 6 wherein a first type of agglomerate comprises a first tracer composition comprising one or more tracers for tracing hydrocarbon flow and a second type of agglomerate comprises a second tracer composition comprising one or more tracers for tracing water flows.

8. A tracer material according to claim 1, wherein the agglomerates comprise two or more tracer compositions.

9. A tracer material according to claim 8, wherein each agglomerate comprises a first tracer composition comprising one or more tracers for tracing hydrocarbon flow and a second tracer composition comprising one or more tracers for tracing water flows.

10. A tracer material according to claim 1 wherein the retaining material is a solid, glass, or viscous liquid having a viscosity of greater than 10.sup.4 Pa*s, that retards the rate of discharge of the tracer composition from the tracer material compared with the rate of discharge from a similar tracer material in the absence of the retaining material.

11. A tracer material according to claim 1, wherein said particles comprise an inorganic oxide material.

12. A tracer material according to claim 11, wherein said particles comprise silica, alumina, an aluminosilicate, porous glass, calcium carbonate, clay, sepiolite, kaolin, bentonite, attapulgite, and halloysite, diatomaceous earth, activated carbon, zeolite, moler earth or fullers earth.

13. A tracer material according to claim 1, wherein said tracer composition comprises a dye, a fluorescent material, an emissive material, a halogenated aromatic compound, a cycloalkanes, or a halogenated aliphatic compound.

14. A tracer material according to claim 1, wherein said tracer composition comprises a solid or liquid which is soluble in or miscible with a hydrocarbon fluid or an aqueous liquid.

15. A tracer material according to claim 1, wherein said tracer composition comprises more than one tracer.

16. A tracer material according to claim 1, wherein said retaining material comprises a polymeric material or a waxy organic material.

17. A tracer material according to claim 16, wherein said retaining material comprises a polyurethane, an epoxy resin, a polyester, an acrylic material, polyvinyl acetate, polyvinyl alcohol, a formaldehyde-based resin, or a cellulose derivative.

18. A tracer material according to claim 1, wherein the tracer material is free-flowing.

19. A tracer material according to claim 1, wherein the tracer material is formed into an agglomerated object.

20. A tracer material according to claim 1, wherein the agglomerates have a sphericity of 0.5 or greater.

21. A tracer material according to claim 1, wherein the agglomerates have a roundness of 0.5 or greater.

22. A tracer material according to claim 1, wherein the agglomerates comprise one or more additional compositions selected from the group comprising strengthening materials, viscosity modifiers, density modifiers, flow modifiers, gelling modifiers, lubricants, foaming modifiers, scale inhibitors, disinfectants, anti-freezes or corrosion inhibitors.

23. A method of making a tracer material comprising the steps of: providing a plurality of particles; applying a tracer composition to the particles; contacting the particles with a liquid precursor to a retaining material; granulating the contacted particles to form a plurality of agglomerates; and treating the agglomerates to form a retaining material from the liquid precursor.

24. A method of making a tracer material comprising the steps of: providing a plurality of particles; applying a tracer composition to the particles; contacting the particles with a liquid precursor to a retaining material; optionally treating the particles to form a retaining material from the liquid precursor; contacting the particles with a second liquid precursor to a binding material; granulating the contacted particles to form a plurality of agglomerates; and treating the agglomerates to form a binding material from the second liquid precursor and, optionally, a retaining material from the liquid precursor.

25. A method of making a tracer material comprising the steps of: providing a plurality of particles; applying a tracer composition to the particles; contacting the particles with a liquid precursor to a retaining material; optionally treating the particles to form a retaining material from the liquid precursor; optionally contacting the particles with a second liquid precursor to a binding material; granulating the contacted particles to form a plurality of agglomerates; and treating the agglomerates so as to (a) form a binding material from the second liquid precursor if present, (b) form a retaining material from the liquid precursor, or both (a) and (b).

26. A method according to claim 25, wherein the binding material, if present, is a solid, glass or viscous material having a viscosity of greater than 10.sup.4 Pa*s.

27. A method according to claim 25, wherein the retaining material is a solid, glass or viscous material having a viscosity of greater than 10.sup.4 Pa*s.

28. A method according to claim 25, wherein the method comprises the step of removing a solvent from the particles after applying the tracer composition to the particles.

29. A method according to claim 25, wherein the plurality of particles are provided by grinding a particulate material.

30. A method according to claim 25, wherein the applying of the tracer composition to the particles comprises applying a tracer composition to the particles in the form of a liquid or a solution.

31. A method according to claim 25, wherein the particles are porous particles and the applying of the tracer composition to the particles comprises impregnating the porous particles with the tracer composition.

32. A method according to claim 25, wherein the method comprises applying one or more additional compositions selected from the group comprising strengthening materials, viscosity modifiers, density modifiers, flow modifiers, gelling modifiers, lubricants, foaming modifiers, scale inhibitors, disinfectants, anti-freezes or corrosion inhibitors.

33. A method of tracing a flow of fluid from a hydrocarbon reservoir comprising the steps of placing within a well penetrating said reservoir a tracer material that comprises a plurality of separate agglomerates, each agglomerate comprising a cluster of particles, wherein the particles carry a tracer composition at least partially overlain by a retaining material and wherein the cluster of particles is bound together by a binding material so as to form the agglomerate, thereafter collecting a sample of fluids flowing from the well and analysing said sample to determine the presence or absence of said tracer composition and optionally determining the concentration of one or more tracers in fluids flowing from the well.

34. The method of claim 33, wherein a plurality of samples of fluids flowing from the well are taken and analysed over a period of time and the concentrations of one or more tracers in the reservoir fluids are determined over time.

35. A method according to claim 33, wherein said tracer material is placed within a fracture in a rock formation forming said reservoir or within, or attached to, a well completion apparatus installed within said well.

Description

DESCRIPTION OF THE DRAWINGS

[0036] The invention will be further described by way of example only with reference to the following figures, of which:

[0037] FIG. 1 is a schematic of a tracer material embodying the present invention.

DETAILED DESCRIPTION

[0038] In FIG. 1 a tracer material 1 is formed from a plurality of agglomerates 2. Each agglomerate 2 is formed from a cluster of particles 3, which carry on their surface 4 and in their pores 5 a tracer composition 6. The tracer composition 6 is at least partially overlain by a retaining material 7. The retaining material 7 also binds the cluster of particles 3 together to form the agglomerate 2.

EXAMPLES

[0039] The invention will be further described in the following examples.

Example 1

[0040] A 50 litre Lodige dryer equipped with rotating ploughs and a steam-heated jacket was charged with 15.65 kg of XR99 calcined moler earth adsorbent particles (available from Lubetech). To this vessel was added (whilst agitating) 12.5 kg of 20% acetone solution of a halogenated aromatic compound (tracer) over a period of several hours. The agitation was continued and heating was applied until all acetone was removed via a reflux apparatus attached to the top of the Lodige vessel body. Several aliquots of a mixture of a commercial bisphenol-A-(epichlorhydrin) epoxy resin, its recommended hardener, and a solvent (acetone) were added to the vessel whilst stirring and heating were continued. The aliquot quantities are given below.

TABLE-US-00001 Aliquot Epoxy resin (kg) Hardener (kg) Acetone (kg) 1 0.575 0.115 0.25 2 0.576 0.115 0.192 3 0.576 0.115 0.145 4 0.578 0.115 0.147 5 0.577 0.115 0.148 6 0.577 0.118 0.140 7 1.440 0.292 0.349 8 1.440 0.288 0.358

[0041] Addition of all above aliquots was carried out at 10 minutes intervals via a peristaltic pump. The vessel heating and agitation were then continued for several hours, whilst the acetone was removed. Following this, agglomeration of the powder had occurred to create agglomerates which ranged in size from <420 m to 20 mm, with the bulk of the material falling between 0.425 and 3 mm.

[0042] Mass recovered from the vessel was 23.1 kg, 94.8% of the amount added. Lost mass is attributed to material not being released from the vessel walls during discharge.

[0043] Of the 23.1 kg which was discharged, 45% (10.4 kg) was between 0.425 and 1.18 mm in size.