Earth boring – well treating – and oil field chemistry – Well treating – Contains organic component
Reexamination Certificate
2002-01-31
2004-07-13
Tucker, Philip C. (Department: 1712)
Earth boring, well treating, and oil field chemistry
Well treating
Contains organic component
C166S293000, C166S295000, C507S269000, C507S277000, C507S901000, C106S607000, C106S632000
Reexamination Certificate
active
06762156
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to improved reactive cement compositions for sealing liquid hydrocarbon containing subterranean zones and methods of utilizing the compositions.
2. Description of the Prior Art
In the drilling of oil and gas wells using the rotary drilling method, drilling fluid is circulated through the drill string and drill bit and then back to the surface by way of the wellbore being drilled. The drilling fluid maintains hydrostatic pressure on the subterranean zones through which the wellbore is drilled and circulates cuttings out of the wellbore. As the wellbore is drilled, formations are encountered which may be too weak to support the hydrostatic pressure of the drilling fluid column, or they have large natural fractures, vugs, or other passages which allow the drilling fluid to flow into the formations. Once the drilling fluid circulation is lost as a result of the drilling fluid entering a subterranean formation by way of fractures, vugs or other passages, the drilling operations must be terminated while remedial steps are taken. Also, when a subterranean zone is penetrated containing fluids at a higher pressure than the hydrostatic pressure of the drilling fluid column, such fluids, e.g., liquid hydrocarbons, flow into the wellbore causing cross-flows or underground blowouts.
Heretofore, a variety of sealing compositions have been developed and used for combatting lost circulation, cross-flows and underground blowouts. However, when the drilling fluid is a hydrocarbon-based fluid or when the fluid cross-flows or underground blowouts are liquid hydrocarbons, such sealing compositions have often been unsuccessful due to delayed and inadequate viscosity development by the sealing compositions.
Recently, oil-based and water-based compositions for sealing subterranean zones have been developed and utilized by Halliburton Energy Services, Inc., of Duncan, Okla. The compositions are the subject matter of U.S. Pat. No. 5,913,364 issued on Jun. 22, 1999 to Sweatman, U.S. Pat. No. 6,060,434 issued on May 9, 2000 to Sweatman et al. and U.S. Pat. No. 6,167,967 issued on Jan. 2, 2001 to Sweatman. While the compositions described in the above patents are very reactive, i.e., they very quickly develop viscosity and have been utilized successfully when the drilling fluid is an aqueous fluid or the cross-flow or blowout fluid is formation water, the sealing composition is not reactive when the fluid in the wellbore is a liquid hydrocarbon fluid.
More recently, very reactive water-based sealing compositions have been developed and utilized by Halliburton Energy Services, Inc., of Duncan, Okla. which are disclosed in U.S. Pat. No. 6,258,757 issued on Jul. 10, 2001 to Sweatman et al. While the sealing compositions are effective when the drilling fluid is a hydrocarbon-based fluid or the cross-flow or blowout fluid is a liquid hydrocarbon fluid and form relatively stiff unpumpable masses when placed and reacted, there are lost circulation, cross-flow and blowout situations which require even greater resistance to flow and compressive strength in order to contain liquid hydrocarbon fluids.
Thus, there are continuing needs for improved lost circulation, cross-flow or blowout sealing compositions which are very reactive and form high strength masses which have compressive strengths when placed and reacted with liquid hydrocarbons.
SUMMARY OF THE INVENTION
The present invention provides reactive water-based cement compositions for sealing liquid hydrocarbon-containing subterranean zones and methods of utilizing the cement compositions which overcome the deficiencies of the prior art and meet the needs described above. The compositions and methods are particularly suitable for sealing subterranean lost circulation zones containing liquid hydrocarbon-based drilling fluids, e.g., oil external-water internal emulsions known as inverted emulsions as well as subterranean zones containing liquid hydrocarbon cross-flows or blowouts.
The water-based cement compositions of this invention for sealing liquid hydrocarbon-containing subterranean zones thereby preventing the uncontrolled flow of liquid hydrocarbons into or from the zones are basically comprised of water, a hydraulic cement, and organophillic clay, a hydratable gelling agent and a water soluble alkaline source, preferably sodium carbonate. When the sealing compositions of this invention contact liquid hydrocarbons, the compositions immediately react to form a high viscosity semi-rigid sealing mass which develops compressive strength.
The methods of this invention for sealing a subterranean zone to prevent the uncontrolled flow of liquid hydrocarbons into or from the zone basically comprise the steps of providing a subterranean zone sealing composition of this invention as described above and then introducing the sealing composition into the zone whereby the zone is sealed and the flow of liquid hydrocarbons into or from the zone is terminated.
The objects, features and advantages of the present invention will be readily apparent to those skilled in the art upon a reading of the description of preferred embodiments which follows.
DESCRIPTION OF PREFERRED EMBODIMENTS
As mentioned above, in the drilling of wells, subterranean zones are often encountered which contain high incidences of natural vugs and fractures. As a result, drilling fluid circulation is often lost which requires the termination of the drilling and the implementation of remedial procedures which are often of long duration and high cost. In addition to drilling fluid lost circulation zones, zones containing pressurized fluids can be encountered which cause formation fluid cross-flows or underground blowouts. Heretofore, sealing compositions have been developed and used successfully for sealing aqueous drilling fluid lost circulation zones and aqueous formation fluid cross-flows and blowouts. However, when the drilling fluid flowing into a lost circulation zone is a liquid hydrocarbon-based fluid, e.g., an oil external-water internal emulsion, or when formation fluid cross-flows or blowouts are liquid hydrocarbons, the heretofore utilized sealing compositions have often been unsuccessful in sealing the lost circulation zones, cross-flow zones or blowout zones.
By the present invention, compositions for sealing subterranean zones to prevent the uncontrolled flow of liquid hydrocarbons into or from the zones are provided. The sealing compositions are basically comprised of water, a hydraulic cement, an organophillic clay, a hydratable gelling agent and a water soluble alkaline source such as sodium hydroxide, sodium aluminate or sodium carbonate, preferably sodium carbonate. The organophillic clay instantaneously reacts with liquid hydrocarbons in the wellbore to form a high viscosity, semi-rigid sealing mass. The gellation and/or hydration of the hydraulic cement by the water is accelerated by the alkaline source in the compositions to quickly provide flow resistance and compressive strength to the compositions. The hydratable gelling agent is present in the compositions to maintain the solids in suspension in the compositions.
The water, in addition to hydrating the hydraulic cement, is present in a quantity sufficient to produce a pumpable slurry. The water can be from any source provided it does not contain compounds that adversely affect the components in the sealing compositions. The water can be fresh water or salt water. The term“salt water” is used herein to mean unsaturated salt solutions and saturated salt solutions including brines and sea water. Generally, the water is present in an amount in the range of from about 15% to about 55% by weight of the compositions, more preferably in the range of from about 25% to about 35%.
A variety of hydraulic cements can be utilized in accordance with this invention including those comprised of calcium, aluminum, silicon, oxygen and/or sulfur which set and harden by reaction with water. Such hydraulic cements include Portland cements, pozzolana cements, gypsum ce
Dealy Sears T.
Heathman James F.
Dougherty, Jr. C. Clark
Halliburton Energy Service,s Inc.
Roddy Craig W.
Tucker Philip C.
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