Method and device for evaluating during drilling the capacity of well fluids to form hydrates

• US 6,571,604 B2
• Filed: 02/06/2002
• Issued: 06/03/2003
• Est. Priority Date: 02/09/2001
• Status: Expired due to Term

• Current Assignee: Institut Francais Du Petrole (IFP Energies Nouvelles)
• Original Assignee: Institut Francais Du Petrole (IFP Energies Nouvelles)
• Inventors: Audibert, Annie, Dalmazzone, Christine, Herzhaft, Benjamin
• Primary Examiner(s): Kwok, Helen
• Assistant Examiner(s): Politzer, Jay L.
• Application Number:
  US10/066,644
• Publication Number:
  US 20020134136A1
• Time in Patent Office: 482 Days
• Field of Search: 73/250.1, 73/310.6, 481/275, 514/300, 514/266.4, 510/224, 585/3
• US Class Current: 73/25.01
• CPC Class Codes: G01K 17/00 Measuring quantity of heat measuring temperature by calorimetry G01K3/00 - G01K11/00; specially adapted for measuring thermal properties of materials, e.g. specific heat, heat of combustion G01N

Abstract

Method of determining the gas hydrate formation conditions in a well fluid, comprising the following stages:

taking a fluid sample,

placing this sample in a calorimetry cell,

performing on this sample a reference thermogram in a temperature range between T1 and T2,

performing on the same sample a second thermogram in the same range and under a pressure Ph of a hydrocarbon gas, T1 being a temperature low enough to obtain the formation of hydrates in the sample at a gas pressure Ph, T2 being high enough to obtain hydrate dissociation,

identifying a peak in the second thermogram corresponding to the hydrates dissociation zone and deducting therefrom a hydrates dissociation temperature.

Claims

1. A method for determining gas hydrate formation conditions in a well fluid, comprising the following stages:

taking a fluid sample,

placing this sample in a calorimetry cell,

performing on this sample a reference thermogram in a temperature range between T1 and T2,

performing on the same sample a second thermogram in the same range and under a pressure Ph of a hydrocarbon gas, T1 being a temperature low enough to obtain the formation of hydrocarbon gas hydrates in the sample at a gas pressure Ph, T2 being high enough to obtain hydrate dissociation,

identifying a peak in the second thermogram corresponding to the hydrocarbon gas hydrates dissociation zone and deducing therefrom a hydrocarbon gas hydrates dissociation temperature,

determining the hydrocarbon gas hydrate formation conditions for the fluid considered.

2. A method as claimed in claim 1, wherein pressure Ph is determined as a function of the pressure of the well fluid close to the zones where the appearance of hydrocarbon gas hydrates is critical.

3. A method as claimed in claim 1, wherein the efficiency of an anti-hydrate additive is tested by adding it to said fluid sample in determined proportions.

4. A method as claimed in claim 1, wherein T1 and T2 are 20°

C. and 35°

C. respectively.

5. A method as claimed in claim 1, wherein the thermograms are obtained with a temperature gradient ranging between 0.5 and 5°

C./minute, preferably at 2°

C./minute.

6. A method as claimed in claim 1, wherein CH4 is used for said gas.

7. A system for implementing the method as claimed in claim 1, characterized in that it comprises in combination a calorimetric measuring device, means for placing the measuring cell of said device under pressure by means of a hydrocarbon gas, thermogram recording means.