Boring or penetrating the earth – With signaling – indicating – testing or measuring – Indicating – testing or measuring a condition of the formation
Reexamination Certificate
2000-02-28
2001-10-30
Suchfield, George (Department: 3672)
Boring or penetrating the earth
With signaling, indicating, testing or measuring
Indicating, testing or measuring a condition of the formation
C073S152030, C166S254200, C507S103000, C507S129000, C507S131000
Reexamination Certificate
active
06308788
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is generally directed to a conductive fluid medium useful in the openhole wireline logging of subterranean wells and in logging-while-drilling. Further, the present invention is directed to a method of using this medium in electrical wireline logging of oil and gas wells and logging while drilling.
2. Description of the Related Art
The use of wireline well logs is well known in the art of drilling subterranean wells and in particular oil and gas wells. A wireline log is generated by lowering a logging tool down the well on a wireline. The tool is slowly brought back to the surface and the instruments on the logging tool take measurements that characterize the formations penetrated by the well in addition to other important properties of the well. Electrical logs and other wireline log techniques are depended upon in the oil and gas exploration industry to determine the nature of the geology and the reservoir properties of the petroleum bearing formations penetrated by the well. Further, wireline well logs are often the only record of the formations penetrated by the well available for correlation amongst different wells in a particular field.
When an electrical wireline log is made of a well, electrodes on the well logging tool are in contact with wellbore fluid or filter cake and hence the formation rocks through which the well has penetrated. An electrical circuit is created and the resistance and other electrical properties of the circuit may be measured while the logging tool is retracted from the well. The resulting data is a measure of the electrical properties of the drilled formations verses the depth of the well. Another common measurement made with an electrical log, besides resistivity, is the spontaneous or self potential. One of skill in the art of well logging and electrical logging in particular should understand how to interpret the results of such measurements to determine the presence or absence of petroleum or gas, the porosity of the formation rock and other important properties of the well. Further information in this regard can be found in the book entitled “Essentials of Modern Open-hole Log Interpretation” by John T. Dewan the contents of which are hereby incorporated herein by reference, and other similar reference material.
An alternative or supplement to wireline logging involves logging tools placed in specialized drill collar housing and run in the drill string near the bit. This technique is known as logging-while-drilling (LWD) or formation-evaluation-while-drilling (FEWD). Measurements such as electrical resistivity can be thereby taken and stored down hole for later retrieval during a “tripping out” of the drill string, or transmitted to the surface via mud-pulse telemetry. Such techniques should be known to one of skill in the art of well drilling and subterranean well logging.
The use of oil-based muds and drilling fluids has become increasingly popular since their introduction of the technology in the 1950's. Innovations in oil-based muds and drilling fluids are of on-going importance with the development of environmentally friendly drilling fluids and fluids having other special characteristics. Oil-based muds offer advantages over water-based muds in many drilling situations. In particular, oil-based muds are known in the art to provide excellent shale inhibition, borehole stability, lubricity, thermal stability, tolerance of contamination and ease of maintenance. Despite the many benefits of utilizing oil-based muds and drilling fluids, they have disadvantages. One such disadvantage addressed by the present invention is that normal resistivity and self potential measurements cannot be taken when the well has been drilled with a conventional oil-based mud or drilling fluid due to the non-conductive nature of the oil-based drilling fluids and muds. Of the many attempts to date, none have met with much success or commercial acceptance in the subterranean well drilling art. Thus there exists an on-going need and desire for drilling fluids and drilling muds that are oil-based and yet allow the taking of wireline electrical logs of the well and electrical-logging-while-drilling.
BRIEF SUMMARY OF THE INVENTION
The present invention is generally directed to providing an oil-base medium suitable for electrically logging a subterranean well. The medium in its continuous phase includes an oleaginous fluid, a polar organic solvent and an electrolytic salt. The continuous phase is in contact with the logging tool and the wellbore of the well. The continuous phase may have dispersed within it fluid droplets or solid particles immiscible with the continuous phase. The oleaginous fluid may be a diesel, mineral oil, vegetable oil, synthetic oil, silicone oil, or combinations of these fluids. The polar organic solvent should be at least partially soluble in the oleaginous fluid, but should also have partial solubility in water. Examples of such polar solvents may include ethylene glycol, diethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, and their alkyl ether derivatives. The electrolytic salt or brine should be selected so that it is at least partially soluble in the mixture of oleaginous fluid and polar organic solvent. Suitable salts or brines may include magnesium chloride, sodium chloride, sodium bromide, potassium chloride, ammonium chloride, calcium chloride, calcium bromide, organic salts or combinations thereof. Organic salts may include salts such as sodium acetate, potassium acetate, sodium citrate, quaternary amine salts or combinations thereof may be used. A quaternary amine salt is preferably utilized in place of or in addition with the aforementioned electrolytic salts. Preferably such quaternary amine salts have the formula:
wherein R is an alkyl having 8 to 18 carbon atoms, R′ is 2 to 6 carbon atoms alkyl group, B is hydrogen, oxyalkyl having 1 to 4 carbon atoms or alkyl having 1 to 4 carbon atoms, A is hydrogen or alkyl with 1 to 4 carbon atoms, x+y=1 to 15, z is 0 to 3, and M− is a counter anion; or combinations thereof. In one preferred embodiment, the electrolytic salt is a quaternary amine salt, having the formula:
wherein M is any suitable anion, preferably halogen, and R being an alkyl have from 10 to 14 carbon atoms. In another illustrative embodiment of the present invention, the quaternary amine salt is isotridecyloxypropyldihydroxyethylmethylammonium chloride, sold under the tradename Q-17-2PG by Tomah Product Inc. of Milton, Wis. USA. The counter-anion to the quaternary amine cation may be the conjugate base of any mineral acid or strong organic acid. Preferably the counter-anion is a halide ion, nitrate ion, sulfate ion, acetate ion, alkyl sulfonate ion, halo-alkylsulfonate ion, or the like.
The logging medium may also include viscosifier or gelling agent, such as clays, organophilic clays, polymers, polyamides, polymer emulsions or combinations thereof and the like. In addition, the logging medium of the present invention may have suspended within it a weight material such as hematite, magnetite, iron oxides, illmenite, barite, siderite, celestite, dolomite, calcite, manganese oxides, halites or combinations of these. The continuous phase of the logging medium comprises the oleaginous fluid together with the polar organic solvent, salt, brine or other materials that may be dissolved therein. These other materials may include corrosion inhibitors, emulsifiers or fluid loss additives.
Another embodiment of the present invention, includes drilling a subterranean well with the fluid of the present invention serving as the medium for logging-while-drilling via a suitable tool in the drill string. Another embodiment includes drilling the subterranean well with a drilling fluid in which the logging medium of the present invention is a component. In such an embodiment, the logging medium should be in sufficient concentration so as to enable one to make electrical log measurements of the subterranean
Bell Rejinald J.
Hoxha Burhan
Patel Arvind D.
Cagle Stephen H.
Howrey Simon Arnold & White , LLP
M-I LLC
Suchfield George
White Carter J.
LandOfFree
Conductive medium for openhole logging and logging while... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Conductive medium for openhole logging and logging while..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Conductive medium for openhole logging and logging while... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2601905