WELL CONDITIONING METHOD FOR WIRELINE LOGGING USING DEDICATED AQUEOUS BASED DRILLING FLUID COMPOSITION

Abstract

The present invention addresses to a wireline logging method using an aqueous based drilling fluid with xanthan gum and polyols in order to improve the quality of the acquisition of geological data from wireline logging (final logging) in open hole and reducing the risk of the tool getting stuck. It can also be applied in well control situations and used in the integral drilling of the reservoir, but with different application bias of the multifunctional fluid.

Claims

1. A WELL CONDITIONING METHOD FOR WIRELINE LOGGING USING DEDICATED AQUEOUS BASED DRILLING FLUID COMPOSITION, characterized in that there is the combination of technology and fluid conditioning comprising the following steps: a) Preparation of the aqueous fluid with polyols according to the following steps: a.1) Pre-hydrate the filtrate viscosifying and reducing polymers with reduced concentrations in industrial water; a.2) Add the NaCl brine; a.3) Add the polyol to the mixture with prehydrated polymers in a.1); a.4) Add precipitating additive of Ca++ and Mg++ ions, buffer additive, alkalizing additive, and bactericidal additive, in the composition, and consider the use of defoamer, if foam formation is evidenced; a.5) Adjust the pH in the alkaline range; a.6) Densify to a specific mass of not less than 1,000 kg/m.sup.3; a.7) Carry out rheology, filtrate and salinity tests; and a.8) Adjust the concentration of filtrate viscosifier and inhibitor polymers; b) Open holes conditioning and fluid pumping: b.1) At the end of the drilling, pump a viscous cushion, a fluid with a rheology superior to that of the active system indicated by the viscometer reading at 3 RPM equal to or greater than 20 degrees, at the bottom and displace with aqueous fluid with polyols with the same weight as the drilling up to 100 m above the casing shoe of the previous phase with drilling flow rate; b.2) Withdraw the drill string by performing backreaming by pumping aqueous fluid with polyols to the cased hole; b.3) From the casing shoe, withdraw the drill string with circulation and without rotation by pumping the aqueous fluid with polyols at a reduced flow rate and controlled speed up to at least 200 m above the shoe or according to the availability of aqueous fluid with polyols; b.4) At the end of pumping the aqueous fluid with polyols, pump 15 to 32 m.sup.3 of viscous cushion, a fluid with a rheology superior to that of the active system indicated by the viscometer reading at 3 RPM equal to or greater than 20 degrees, and proceed with the withdrawal of the string in a cased hole by pumping the fluid from the system; b.5) After passing the viscous cushion through the BOP, turn on the booster; b.6) From the pre-defined depth, complete the withdrawal of the string.

2. THE WELL CONDITIONING METHOD FOR WIRELINE LOGGING USING DEDICATED AQUEOUS BASED DRILLING FLUID COMPOSITION according to claim 1, characterized in that the polymers in step a.1) are the xanthan gum viscosifier and the filtrate reducers are polyanionic cellulose and hydroxy-propyl-amide.

3. THE WELL CONDITIONING METHOD FOR WIRELINE LOGGING USING DEDICATED AQUEOUS BASED DRILLING FLUID COMPOSITION according to claim 1, characterized in that the pH adjustment in step a.5) is in the range of 9.0 to 10.5.

4. THE WELL CONDITIONING METHOD FOR WIRELINE LOGGING USING DEDICATED AQUEOUS BASED DRILLING FLUID COMPOSITION according to claim 1, characterized in that the concentration of NaCl brine from step a.2) is placed between 26.0% v/v to 49.0% v/v.

5. THE WELL CONDITIONING METHOD FOR WIRELINE LOGGING USING DEDICATED AQUEOUS BASED DRILLING FLUID COMPOSITION according to claim 1, characterized in that the use of sodium bicarbonate precipitating additive of Ca++ and Mg++ ions in step a.4) is at the concentration of 1.43 to 2.86 kg/m.sup.3.

6. THE WELL CONDITIONING METHOD FOR WIRELINE LOGGING USING DEDICATED AQUEOUS BASED DRILLING FLUID COMPOSITION according to claim 1, characterized in that the use of the magnesium oxide buffer additive in step a.4) is at the concentration of 1.43 at 4.29 kg/m.sup.3.

7. THE WELL CONDITIONING METHOD FOR WIRELINE LOGGING USING DEDICATED AQUEOUS BASED DRILLING FLUID COMPOSITION according to claim 1, characterized in that the use of the caustic soda alkalizing additive in step a.4) is at the concentration 0.86 to 1.43 kg/m.sup.3.

8. THE WELL CONDITIONING METHOD FOR WIRELINE LOGGING USING DEDICATED AQUEOUS BASED DRILLING FLUID COMPOSITION according to claim 1, characterized in that the use of the glutaraldehyde bactericidal additive in step a.4) is at the concentration of 0.29 to 0.86 kg/m.sup.3.

9. THE WELL CONDITIONING METHOD FOR WIRELINE LOGGING USING DEDICATED AQUEOUS BASED DRILLING FLUID COMPOSITION according to claim 1, characterized in that the use of the silicone-based emulsion defoam additive in step a.4) is at the concentration of 0.86 at 1.43 kg/m.sup.3.

10. THE WELL CONDITIONING METHOD FOR WIRELINE LOGGING USING DEDICATED AQUEOUS BASED DRILLING FLUID COMPOSITION according to claim 1, characterized in that it densifies to the specific mass in step a.6) in the range of 1,000 to 2,000 kg/m.sup.3.

11. THE WELL CONDITIONING METHOD FOR WIRELINE LOGGING USING DEDICATED AQUEOUS BASED DRILLING FLUID COMPOSITION according to claim 10, characterized in that it densifies to the specific mass in step a.6) preferably in the range of 1,000 to 1,500 kg/m.sup.3.

12. THE WELL CONDITIONING METHOD FOR WIRELINE LOGGING USING DEDICATED AQUEOUS BASED DRILLING FLUID COMPOSITION according to claim 1, characterized in that it uses polyols with two to three hydroxyls and with two to six carbon atoms.

13. THE WELL CONDITIONING METHOD FOR WIRELINE LOGGING USING DEDICATED AQUEOUS BASED DRILLING FLUID COMPOSITION according to claim 12, characterized in that it uses the glycerin or monoethylene glycol or diethylene glycol polyols.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0012] The present invention will be described in more detail below, with reference to the attached figures which, in a schematic form and not limiting the inventive scope, represent examples of its embodiment. In the drawings, there are:

[0013] FIG. 1 shows a schematic drawing of (i) the side view of the well and (ii) the top view of the well in the logging operation with aqueous drilling fluid and the appearance of the cake and the well, where there are represented: A—permeable formation; B1—cake of aqueous drilling fluid; C1—annular space filled with aqueous drilling fluid; and D—wireline logging tool;

[0014] FIG. 2 illustrates the appearance of the cake and the well from (i) the side view of the well and (ii) the top view of the well after well conditioning with backreaming and simultaneous pumping of an aqueous fluid with polyols, where there are represented: A—permeable formation; B1—cake of aqueous drilling fluid; B2—cake of the aqueous fluid with polyols; C1—annular space filled with aqueous drilling fluid; C2—annular space filled with aqueous fluid with polyols; D—wireline logging tool; and E—drill string;

[0015] FIG. 3 shows a schematic drawing of (i) the side view of the well and (ii) the top view of the well from the logging operation with polymeric aqueous based complementary fluid (ABCF) with xanthan gum and polyols and the appearance of the cake and the well, where there are represented: A—permeable formation; B2—cake of the aqueous fluid with polyols; C2—annular space filled with aqueous fluid with polyols; D—wireline logging tool.

DETAILED DESCRIPTION OF THE INVENTION

[0016] The method that combines technology and fluid conditioning in open holes according to the present invention comprises: [0017] a) Preparation of the aqueous fluid with polyols according to the following steps: [0018] a.1) Pre-hydrate the filtrate viscosifying and reducing polymers with reduced concentrations in industrial water; [0019] a.2) Add the NaCl brine; [0020] a.3) Add the polyol to the mixture with prehydrated polymers in a.1); [0021] a.4) Add precipitating additive of Ca++ and Mg++ ions, buffer additive, alkalizing additive, and bactericidal additive, in the composition, and consider the use of defoamer, if foam formation is evidenced; [0022] a.5) Adjust the pH in an alkaline range between 9.0 and 10.5; [0023] a.6) Densify to a specific mass of not less than 1,000 kg/m.sup.3, in the range of 1,000 to 2,000 kg/m.sup.3, preferably in the range of 1,000 to 1,500 kg/m.sup.3; [0024] a.7) Carry out rheology, filtrate and salinity tests; and [0025] a.8) Adjust the concentration of filtrate viscosifying and inhibitor polymers.

[0026] With this, the steps of conditioning the open holes and pumping fluid are carried out, verifying the considerations of speed of withdrawal of the drill string, with and without circulation, as well as the volume of fluid required during the planning of the backreaming, comprising the following steps: [0027] b) Open holes conditioning and fluid pumping: [0028] b.1) At the end of the drilling, pump a viscous cushion, a fluid with a rheology superior to that of the active system indicated by the viscometer reading at 3 RPM (rotations per minute) equal to or greater than 20 degrees, at the bottom and displace with aqueous fluid with polyols with the same drilling weight up to 100 m above the casing shoe of the previous phase with drilling flow rate; [0029] b.2) Withdraw the drill string by performing backreaming by pumping aqueous fluid with polyols to the cased hole; [0030] b.3) From the casing shoe, withdraw the drill string with circulation and without rotation by pumping the aqueous fluid with polyols at a reduced flow rate and controlled speed up to at least 200 m above the shoe or according to the availability of aqueous fluid with polyols; [0031] b.4) At the end of pumping the aqueous fluid with polyols, pump 15 to 32 m.sup.3 of viscous cushion, a fluid with a rheology superior to that of the active system indicated by the viscometer reading at 3 RPM equal to or greater than 20 degrees, and proceed with the withdrawal of the string in a cased hole by pumping the fluid from the system; [0032] b.5) After passing the viscous cushion through the BOP, turn on the booster; [0033] b.6) From the pre-defined depth, complete the withdrawal of the string.

[0034] The flow rate during the backreaming may be higher, depending on the autonomy of aqueous fluid with polyols.

[0035] If there has been counteracting the loss of circulation during drilling, do not perform the backreaming in the region where there was the loss so as not to induce a new loss. In this case, it is only necessary to withdraw the string with circulation, pumping fluid with polyols.

[0036] Evaluate the parameters of ECD (Equivalent Circulating Density—equivalent specific mass of fluid circulation) and ESD (Equivalent Static Density—specific mass equivalent to the static pressure exerted by the fluid) to optimize the speed of withdrawal of the string. These parameters will subsidize the withdrawal of the string from the cased well.

[0037] The scheduled withdrawal of string without expected circulation will be an estimate based on hydraulic simulations (swab); however, the depth where the withdrawal without circulation will start as well as the maneuvering speeds will be adjusted with the ECD and ESD data of the PWD.

[0038] Once the reservoir is drilled, the string is withdrawn by positioning this aqueous fluid with polyols, in order to withdraw the cake previously formed during drilling and putting this new fluid in contact with the formation. This aqueous fluid with polyols, for having a low filtrate, provides a very effective and low thickness cake. As there is little fluid infiltration, there is no thickening of the cake over time. This is due to the high affinity (chemical interaction) of polyols for the fluid polymers (xanthan gum and PAC—polyanionic cellulose), which are polyhydroxylated saccharides.

[0039] The increase in the concentration of polyols in the cake during the filtration process is due to the partitioning phenomenon and with that the permeability of the cake reduces, which increases its effectiveness and reduces the invasion of the filtrate in the formation.

[0040] It is also considered that the fluid contains a lower solids content, due to the high density of the polyols, which provides an environment of lower risk of differential sticking, and also increases the recovery/effectiveness of side rock samples.

[0041] The high resistivity provides better resistive imaging data acquisition and for nuclear magnetic resonance data acquisition.

[0042] The fluid's characteristic of inhibiting the formation of hydrates allows the circulation of hydrocarbons in this fluid, enabling the post-sampling fluid circulation without the need for an exclusive conditioning string running down (shorter operating time).

[0043] In addition to the increase in performance in wireline logging operations, the use of this fluid only in the open hole, combined with post-drilling conditioning, reduces material and logistical costs and the risk of unforeseen demand for this fluid in the events of loss of circulation when the well is fully filled with this fluid.

[0044] Furthermore, since this fluid must be prepared prior to the logging operation, it can be used as a hydrate inhibitor in well control situations.

[0045] In table 1, below, the composition of the aqueous fluid with polyols is presented, with the description of the additives and their respective concentration ranges (minimum and maximum), with the values presented in SI system units (kg/m.sup.3) and also in English units (lbm/gal).

TABLE-US-00001 TABLE 1 Composition of the aqueous fluid with polyols, with the description of the additives and their respective concentration ranges. Concentration Concentration lbm/bbl kg/m.sup.3 Additive Function Min. Max. Min. Max. Industrial Continuous  0.0% 54.0%  0.0% 54.0% water phase v/v v/v v/v v/v NaCl brine Weight 26.0% 49.0% 26.0% 49.0% adjustment v/v v/v v/v v/v Sodium Precipitate 0.5 1.0 1.43 2.86 Bicarbonate Ca++ and Mg++ Magnesium Buffer 0.5 1.5 1.43 4.29 oxide Caustic soda Alkalizer 0.3 0.5 0.86 1.43 Glutaraldehyde Bactericidal 0.1 0.3 0.29 0.86 Xanthan Gum Viscosifier 0.7 1.5 2.00 4.29 HPA Filtrate 4.0 6.0 11.44 17.15 reducer PAC L Filtrate 2.0 3.0 5.72 8.58 reducer Baritine Densifier 0.0 60.0 0.00 171.53 Silicone-based Defoamer 0.3 0.5 0.86 1.43 emulsion Polyol Hydrate 15.0% 50.0% 15.0% 50.0% suppressor v/v v/v v/v v/v Notes: concentration in lbm/bbl and kg/m.sup.3 for and in % v/v for industrial water, NaCl brine and polyol. Min.: minimum value, Max.: maximum value. HPA-hydroxy-propyl-amide, PAC L-low viscosity polyanionic cellulose.

[0046] The polyols used in the formulation can have two, three or more hydroxyl groups and with two to six carbon atoms. The polyols can be selected from glycerin, monoethylene glycol, diethylene glycol, for example.

EXAMPLES

[0047] The following examples are presented in order to illustrate some particular embodiments of the present invention, and should not be interpreted as limiting the same. Other interpretations of the nature and mechanism of obtaining the components claimed in the present invention do not alter the novelty thereof.

Example 1

[0048] In table 2 below, there are presented bench results of resistivity, rheology and filtrate comparative between aqueous drilling fluid and aqueous fluid with polyols. As can be seen, the aqueous fluid with polyols performs much better than the aqueous fluid without this additive, as indicated by the higher resistivity, smaller filtrate volume and larger angles. The tests were performed in accordance with API RP 13B-1/ISO 10414-1:2008, which describes the analyses for field tests of aqueous fluids.

TABLE-US-00002 TABLE 2 Bench results for comparative resistivity, rheology and filtrate comparative between aqueous drilling fluid and aqueous fluid with glycerin. Rheology Aqueous fluid Aqueous fluid with FANN 35 (25° C.) glycerin (25° C.) (rpm) θ (measure of the angle) 600 69 87 300 49 61 200 40 50 100 28 35  6 10 12  3 8 10 G′ 10 12 G′′ 17 20 API Filtrate 4.4 2.6 Volume (mL) Resistivity 0.091 0.151 (Ω/m) Key: G′-initial gel of the fluid after 10 s and G′′-final gel of the fluid after 10 min.

[0049] It should be noted that, although the present invention has been described in relation to the attached drawings, it may undergo modifications and adaptations by technicians skilled on the subject, depending on the specific situation, but provided that it is within the inventive scope defined herein.