US3712380A

US3712380A - Method for reworking and cleaning wells

Info

Publication number: US3712380A
Application number: US00093859A
Authority: US
Inventors: P Caffey
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-11-30
Filing date: 1970-11-30
Publication date: 1973-01-23
Anticipated expiration: 1990-01-23

Abstract

A method for reworking and cleaning a well which comprises the steps of setting a packer in the well bore above the formation surrounding the well bore to be treated, inserting tubing through the packer, pumping a mixture of calcium carbide in a liquid hydrocarbon carrier into the area of the well bore to be treated, pumping a hydrocarbon through the tubing to force all of the calcium carbide and liquid hydrocarbon carrier into the area to be treated, pumping an aqueous solution of hydrochloric acid through the tubing, packer and into the well bore and surrounding formation, pumping a liquid hydrocarbon into the tubing to force the calcium carbide, the hydrocarbons and the hydrochloric acid into the formation to be treated, and securing the well bore to prevent escape of the reactants, is disclosed.

Description

United States Patent 1 [111 3,712,380 Caffey [451 Jan. 23, 1973 [54] METHOD FOR REWORKING AND 57 ABSTRACT CLEANING WELLS A method for reworking and cleaning a well Whlch [76] Invent: Caffey, BOX Hermes comprises the steps of setting a packer in the well bore y Ok1a'73742 above the formation surrounding the well bore to be [22] Filed: No 30, 1970 treated, inserting tubing through the packer, pumping a mixture of calcium carbide in a liquid hydrocarbon pp 93,859 carrier into the area of the well bore to be treated, pumping a hydrocarbon through the tubing to force all 52 us. c1 "166/300, 166/307 the calcium carbide and liquid hydrocarbm carrier 51 Int. Cl. ..E24b 43/25 the area be treated Pumping aquews [58] Field of Search 166/300 305, 307 270 271 tion of hydrochloric acid through the tubing, packer 166/272. 252/855C and into the well bore and surrounding formation, pumping a liquid hydrocarbon into the tubing to force [56] References Cited the calcium carbide, the hydrocarbons and the hydrochloric acid into the formation to be treated, UNITED STATES PATENTS and securing the well bore to prevent escape of the reactants, is disclosed. 2,943,681 7/1960 Barrett ..l66/300 7 1,806,499 5/1931 Ranney ..l66/30O 6 Claims, No Drawings- Primary Examiner-Robert L. Wolfe Aztorney-Robert G. McMorrow M... a I" METHOD FOR REWORKING AND CLEANING WELLS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to the reworking of oil and gas wells. More particularly, this invention relates to an improved process for the reworking of oil, gas, salt water disposal and water flood injection wells.

2. Description of the Prior Art It is known that in certain instances it is necessary to apply pressure or to use displacement techniques in the recovery of oil and gas from wells. Generally, in order to tap a source of oil or gas, it is necessary to not only fracture the strata surrounding the source to provide access of the oil or gas to the well bore for recovery, but also it is sometimes necessary to displace the oil or gas by pumping liquids such as water or salt water into the surrounding strata to displace the oil or gas.

Various methods are known for fracturing the surrounding strata and for displacing the oil or gas. Wells can be fractured utilizing both mechanical and chemical-mechanical means, e.g., using the pressure of a liquid forced into the strata around a well bore to fracture the strata surrounding the well bore or by chemically generating a pressure using a reaction in which a gas is liberated in a confined space, which will generate a forcible pressure, and utilizing this pressure alone or in combination with an applied mechanical pressure, as for example, hydraulically, to fracture the surrounding strata. One such method is known and involves the in situ generation of acetylene by the reaction of calcium carbide and water to produce the pressure needed for fracturing. However, this method has the disadvantage that the reaction products, calcium carbonate, results in the formation of lime deposits which can plug and impede the flow of oil even where the strata has been fractured to increase the accessibility to the oil and gas reserves.

Methods are also known whereby oil or gas reserves must be displaced forcibly in order to force the oil or gas reserves to the surface. Such methods involve the displacement of the oil and gas by pumping water or salt water into the area, thus forcing the oil or gas to the surface due to the pressure of the water or salt water used as a displacement liquid. Due to the incompatability of water and oil, emulsions can be formed which thereby impede the flow of the oil.

As a result of the necessity for using displacing means to tap certain oil or gas sources, or the need to fracture the surrounding strata to obtain access to the oil or gas sources, one necessarily must introduce foreign materials into the oil well bore and oil bearing strata to accomplish these ends. This results in the creation of residues in the oil bearing strata, the formation of oil-water emulsions which are difficult to break, or the plugging of the strata or the oil bore itself. These problems may not only reduce the yield of the well, but also could render the well completely unproductive due to plugging, reduced flow and the like.

Accordingly, it is an object of this invention to provide a process for the reworking of oil and gas wells, and in particular those requiring fracturing, salt water disposal and water flood injection techniques wherein the above-described problems are minimized and eliminated.

It is also an object of this invention to provide a process whereby any oil residues can be liquifled, oilwater emulsions can be broken, and solids can be removed to increase the efficiency and productivity of oil and gas wells.

Additionally, it is an object of this invention to provide a method whereby the well can not only be fractured, increasing the access to oil in the surrounding strata, but also whereby the channels previously created in the strata surrounding the well bore can be cleaned as well as to render removable any solids, residues or difficult to handle liquids present in the strata fractures or well bores.

SUMMARY OF THE INVENTION The objects of this invention are accomplished according to the method described herein. The method of this invention is a method for reworking a well and comprises the steps of l. setting a packer in the bore of a well above the perforations of the formation surrounding said well bore to be treated;

. inserting tubing through said packer;

3. pumping a mixture of calcium carbide and a liquid hydrocarbon carrier through said tubing and said packer into said well bore and said formation surrounding said well bore;

. pumping a hydrocarbon through said tubing to force all of said mixture of calcium carbide and a liquid hydrocarbon carrier into said well bore and surrounding formation;

5. pumping an aqueous solution of hydrochloric acid through said tubing and said packer and into said well bore and surrounding formation;

. pumping a liquid hydrocarbon into said tubing to force said calcium carbide, said hydrocarbons and said hydrochloric acid into said formation surrounding said well bore; and

7. securing said well bore to prevent escape of said reactants during said reaction.

DETAILED DESCRIPTION OF THE INVENTION The process of this invention contemplates the use of a chemical reaction to generate heat in the well bore and in the formation surrounding the well bore by the chemical reaction of reactants injected into the well. By the injection of calcium carbide and an aqueous solution of hydrochloric acid, removal of any corrosion, solid or waxy paraffins and hydrocarbons, and oil water emulsions, which may restrict the natural flow of previously fractured oil and gas formations, results. In addition, after the use of the method of this invention, the pressure needed to inject fluids into salt water and water flood injection wells is reduced, thereby not only increasing the productivity of said well, but in addition, making these types of well more economical to operate.

In the first step of the process of this invention, a packer or a plug is placed in the bore of a well at an area in the well bore above the formation of the well bore to be treated. Generally, the strata to be treated surrounding the well bore will have been previously fractured, as for example, using conventional means such as liquids under pressure and the like. This packer is set approximately 50 to feet, preferably from about 30 to 60 feet, above the fractured perforations of the formation or strata to be treated to close off the well bore so that the chemical reaction described hereinafter is confined and localized in that area of the well bore and the surrounding perforations which are to be treated. Suitable packers are well known in the art, and those generally used in the fracturing of a well are suitable. Where it is desired to localize the treatment area further, packers can be set in the well bore both above and below the area to be treated.

Once the packer has been set in the well bore, a tubing is inserted through the packer for use in pumping of the materials utilized in the later steps of the process into the area to be treated. Where two packers are used, the tubing is inserted into the upper packer. The tubing runs from the packer to the surface of the well and possesses means for completely closing off the area such that once all of the reactants are introduced into the area of the well bore to be treated, they are not forced out through the packer and the tubing to the surface, but rather are confined in the localized area below the packer.

Once the tubing has been inserted into the packer, a mixture of calcium carbide and a liquid hydrocarbon carrier is pumped through the tubing and the packer into the well bore to be treated and into the surrounding formation. Suitable hydrocarbons which can be used in this step of the process of the invention are materials such as gelled kerosene, light naphthas, gasoline, crude and refined oil having an A.P.l. gravity of from 12 to 25. The gelling of kerosene, naphthas, gasoline and crude is done with caustic and soaps as is well known in the art. All that is necessary for the liquid hydrocarbon carrier is that it be inert to the calcium carbide and substantially free of water which might cause a premature reaction of the calcium carbide. The calcium carbide particles are dispersed in the liquid hydrocarbon carrier and subsequently pumped through the tubing and packer and into the area to be treated. The size of the calcium carbide particles which are used is not a critical consideration, however, it is desired that the size be such that mixing, pumping and dispersion is facilitated, settling is minimized, and a surface area is provided which, on contact with the hydrochloric acid and water forced into the well area in a later step of the process of this invention, can react smoothly and rapidly to cause the generation of the temperatures desired for the reworking of the well and the formation surrounding the well bore. The size of the calcium carbide generally used will generally range from 8 mesh to a 40 mesh, preferably from to 40 mesh, although as indicated above, the size of the calcium carbide particles used is not a critical consideration. However, use of a particle size larger than 8 can result in handling and pumping difficulties and with a particle size smaller than 40 does not result in any advantages in its use.

In this step of the process of the invention, the calcium carbide will generally be used in the ratio of from 3 to 16 percent by weight to the liquid hydrocarbon carrier. The weight ratio of the calcium carbide to the hydrocarbon carrier ranges from one-half pound per gallon to 1 pound per gallon. Generally, a suitable amount of the hydrocarbon carrier/calcium carbide mixture to be used ranges from 1 gallon to 2 gallons per pound of the hydrochloric acid described hereinafter. It is to be recognized that the amount used will depend upon the extent of the fracturing, the porosity of the surrounding rock strata and the like.

In the next step of the process of this invention, a hydrocarbon such as lease crude or distillate is pumped through the tubing and the packer to force all of the mixture of the calcium carbide and the liquid hydrocarbon carrier into the well bore and the surrounding formation. This not only accomplishes the displacement of the calcium carbide into the area of the well to be treated, but minimizes any reaction of calcium carbide and the aqueous hydrochloric acid solution injected in the later step of the process of this invention from generating heat and pressure due to the reaction of the calcium carbide and the aqueous hydrochloric acid solution in the tubing area. Not only does this give rise to a more efficient use of the process of this invention but minimizes any difficulties which might be encountered by the in situ generation in the tubing of the heat and pressure due to the reaction of the calcium carbide and the aqueous solution of the hydrochloric acid. In addition, the forcing of the hydrocarbon through the tubing to displace the mixture of the calcium carbide and the liquid hydrocarbon carrier used in a previous step not only minimizes any difficulties which might arise as a result of the in situ generation in the tubing but in addition provides for the displacement further of the liquid hydrocarbon and calcium carbide into the surrounding rock strata to be cleaned and reworked.

In the next step of the process of this invention, an aqueous solution of hydrochloric acid is pumped through the tubing and the packer into the well bore and surrounding formation in order to contact the aqueous solution of the hydrochloric acid with the calcium carbide previously pumped into the well bore and the surrounding formation. In this step of the process of this invention, the second reactant, the aqueous solution of the hydrochloric acid, is forced into the area below the packer and into contact with the first reactant, the calcium carbide, resulting in the reaction of the calcium carbide and the water contained in the aqueous solution. Heat is generated due to the reaction of the calcium carbide and the water forming acetylene gas. The amount of the aqueous solution of the hydrochloric acid will be dependent upon the amount of the calcium carbide used, but generally will range from 1 gallon of acid to 1.5 gallons of acid for each pound of calcium carbide used. Use of less than 1 gallon of acid or greater than 2 gallons of acid generally reduces the efficiency of the process either due to incomplete reaction or the larger volumes of acid which must be pumped into the area to be treated. it is generally desired that an excess of the aqueous solution of hydrochloric acid be used in order to insure that all of the calcium carbide has reacted, resulting in a more efficient operation of the process of this invention. Generally, the concentration of the hydrochloric acid used will range from 1 to about 28 percent by weight. Although a concentration of from 1 to about 28 percent hydrochloric acid generally is used in this step of the process of this invention, the amount of the acid used will be determined not only by the amount of calcium carbide used, but also by the characteristics of the formation and the condition of the well to be treated.

For example, such factors as limestone, sandstone, and solubilities of each may determine that a greater or lesser amount of the hydrochloric acid solution be used. More acid will be required in limestone formations due to the solubility of the formation itself. Generally, an amount of from 1 to L5 barrels of the aqueous solution of the hydrochloric acid ranging from 1 to 28 percent by weight can be used for each barrel of the calcium carbide liquid hydrocarbon mixture previously pumped into the well bore and surrounding formation and is suitable. Use of less than a 1 percent solution of the hydrochloric acid generally does not provide sufficient acid to dissolve the calcium carbonate formed as a reaction product and use of a concentration greater than 28 percent generally does not provide any additional advantages.

This step of the process of this invention is followed by a pumping of a liquid hydrocarbon into the tubing to force all of the calcium carbide, the hydrocarbons used and the hydrochloric acid solution into the area below the packer and into the formation surrounding the well bore such that the in situ reaction of the calcium carbide and the water occurs in the area of the well bore and the rock formation to be treated. Upon the mixing of these materials, the calcium carbide reacts with the aqueous hydrochloric acid solution generating temperatures in the formation in excess of about 475F and simultaneously acetylene is released into the formation due to the reaction. This in situ generation of heat and pressure causes a melting of any paraffins, oil residues and a breaking of any hydrocarbon and water emulsions which might be restricting the natural flow of the oil through the surrounding formations and the well bore. Not only does the heat and pressure cause the melting of paraffin residues, hydrocarbon plugs and the like in the well bore and the surrounding formation, but the heat and pressure clean the fractures of the surrounding formation such that access to the oil and gas reserves in the formation through the fractures is improved and also for those wells at which liquid displacement is necessary to obtain the oil and gas reserves. The pressures needed to accomplish this displacement are markedly reduced due to the cleaning and clearing of not only the well bore but the fracture surrounding the well bore. The temperatures generated in situ and the gas generated in situ disturb the surroundings, increasing the flow of the oil or gas molecules in the formation, causing them to move to the fractures into the well bores. Thus, the generation of the heat and pressure not only reduces the amount of work which is necessary to tap the oil reserves, but also leads to an increase in productivity of the well due to the disturbing of the surrounding strata restricting the free movement of the oil molecules in the formation through the fractures to the bore.

The hydrochloric acid used in this step of the process of this invention not only increases the rate of reaction between the calcium carbide and the water, but also neutralizes and dissolves any lime deposits which would be left in and on the formation as a result of the reaction product formed by the reaction of the calcium carbide and water. The acid not only dissolves the lime formed as a result of the reaction, but increases the rate at which the thermal reaction occurs, providing a higher degree of temperature in the formation and a shorter period of time for the reworking of the well.

Once the liquid hydrocarbon pumped into the well bore through the tubing and the packer is displaced in the well, the well bore is closed or secured in such a manner that the escape of the reactants through the packer and the tubing to the surface is prevented and the reaction of the calcium carbide and the aqueous solution of the hydrochloric acid is localized in the area of the well bore to be treated. This is done not only as a safety precaution to prevent escape of the reactants due to the pressure build-up and the high temperatures generated, but also to utilize efficiently the reactants in the area of the well bore and formation to be treated.

Generally once the well bore is secured, the reactants are held in the area below the packer for a period of time sufficient to allow the generation in situ of the temperatures set forth above to maximize the thermal reaction for the reworking of the well bore and the surrounding strata. Generally, this period of time will range from about 4 to about 12 hours.

Once the reaction between the calcium carbide and the aqueous hydrochloric acid solution has run its course, the liquids contained in the well bore and surrounding strata can be allowed to flow back to the surface of the well or be pumped back, if necessary, and the well be cleaned and swabbed where desired. As indicated above, the temperatures generated in situ liquifies any hydrocarbon residue pluggings, breaks any oil and water emulsions and generally cleans not only the well bore but the surrounding strata increasing the productivity and minimizing the difficulty in recovering the oil and gas reserves present in the well area. In addition, by the use of the method of this invention, no lime deposits are created as reaction products which could plug or reduce the productivity.

As indicated above, this invention provides a method for reworking a well in order to increase the productivity of the well, to remove any foreign materials causing difficulty in attaining access to the oil and gas reserves present therein and results in a well which is easier to tap and which can be operated more efficiently.

in order to illustrate the advantages of the process of this invention for melting a hydrocarbon residue and to show the advantageous results obtained due to the use of hydrochloric acid in preventing lime deposits which could ultimately reduce the effectiveness of the process, the following examples are provided to illustrate the process of this invention without thereby limiting the process of the invention.

EXAMPLES Eight wells have been subjected to the treatment of the process of this invention. Described below is the treatment on two of the wells. These two wells are producing oil and gas wells. The other wells treated have responded similarly.

The first well treated was a Mississippi limestone well. it was stimulated by a large water-frac type treatment, with approximately 12,000 barrels of water being used. This is an average size treatment and is conventionally used in this area. The production of the well as completed was barrels of oil per day (BOPD) and 1.2 MM cubic feet per day (CFD). In four years production had declined to 3 BOPD and 35 M CFD.

The well was treated according to the process of this invention using the following steps: Tubing and packer were run into the well and the packer set approximately 35 feet above the perforations of the strata to be treated. Lease oil was then pumped via tubing to fill the tubing and pump into the formation to ensure the zone would accept the treatment. Next, 800 pounds of calcium carbide and 800 gallons of refined l8 gravity oil were mixed in a paddle mixer tank. This resulted in a total volume of approximately 1,000 gallons. This mixture was then pumped into the well via the tubing and without stopping the pump a barrel spacer of the lease oil was pumped. The spacer of lease oil prevented the calcium carbide mixture and the acid subsequently pumped into the well from reacting in the tubing or well bore. Immediately following the 15 barrel lease oil spacer, 1,500 gallons of a 15 percent aqueous hydrochloric acid was pumped into the well via the tubing. The acid was then displaced with lease oil down the tubing and out into the zone to contact the calcium carbide. Surface pumping pressure during the operation varied from 1,000 psi to 3,000 psi. The well was then shut in for 12 hours. The well was opened the next morning and flowed and swabbed to recover the treatment fluid. All the fluid, acid water and lease oil was recovered in 18 hours and the well was flowing with 100 psi on the tubing.

Ninety days after the treatment by the process of this invention, the well was producing 18 BOPD and 8 BWPD with 180 M CFD. The water was tested and was believed to be the frac water used in the original treatment in 1965, since the well was not making any water prior to the treatment.

The second well treated was a comingled Cromwell (sandstone) and Hunton (limestone) well in southern Oklahoma. The original completion was in the Hunton zone only and produced after an acid treatment, for 8 years. At that time an acid-frac treatment was done on the Hunton zone, and the Cromwell zone was opened and fracture treated with a sand-oil treatment. In 12 years production had declined from over 100 BOPD to 8 BOPD. This well was treated as follows:

Tubing and packer were run and set 50 feet above both zones. Ten feet of Cromwell and 20 feet of Hunton were open. A sufficient volume of lease oil was pumped via the tubing to ensure the zones would accept the treatment. 800 pounds of calcium carbide and 800 gallons of refined 20 gravity oil were mixed and the one-half of the mixture, approximately 500 gallons, was pumped into the well via the tubing and followed with 10 barrels of a lease oil spacer. Then 750 gallons of a 15 percent aqueous hydrochloric acid were pumped and displaced clear of the packer. Forty /a inch rubber ballsealers in lease oil were injected and pumped via the tubing to plug off the perforations of one of the zones. The above steps were repeated to treat one-half the treatment in each of the open zones. The surface pumping pressures on the first zone were approximately 750 psi and on the second zone the pressure was 850 psi. The pressure differences indicated two different zones were treated. After the treatment fluids were swabbed back, the well was put into production and has been averaging 40 BOPD.

What is claimed is:

1. A method for reworking and cleaning a previously fractured and acidized well comprising the steps of 1. setting a packer in the bore of a well above the perforation of the formations surrounding said well bore to be treated;

2. inserting tubing through said packer;

3. pumping a mixture of calcium carbide and a liquid hydrocarbon carrier which is inert to the calcium carbide and free of water through said tubing and said packer into said well bore and said formation, wherein the weight ratio of the calcium carbide to the liquid hydrocarbon carrier ranges from onehalf pound per gallon to 1 pound per gallon;

4. pumping a hydrocarbon through said tubing to force all of said mixture of calcium carbide and the liquid hydrocarbon carrier into said well bore and surround formation;

6. pumping a liquid hydrocarbon into said tubing to force said calcium carbide, said hydrocarbons and said aqueous solution of hydrochloric acid into said formation surrounding said well bore, said calcium carbide and said aqueous solution of hydrochloric acid then being in reactive contact, wherein the concentration of the aqueous solution of hydrochloric acid ranges from 1 to 28 percent by weight, and wherein the volume ratio of the aqueous solution of hydrochloric acid to the calcium carbide ranges from 1 to 2 gallons per pound; and

7. securing said tubing to prevent escape of said reactants, the calcium carbide and water reacting exothermally to yield gaseous acetylene and lime, the exothermic heat of reacting melting any paraffins and oil residues present and the pressure of the gaseous acetylene breaking any hydrocarbon and water emulsions present and cleaning the formation, the hydrochloric acid accelerating the calcium carbide-water reactions and in situ reacting with the lime to thereby avoid lime deposits in the formation.

2. A method for reworking and cleaning a previously fractured and acidized well comprising the steps of 1. setting packers in a well bore above and below the perforations of the formations surrounding said well bore to be treated;

2. inserting tubing through the upper packer;

3. pumping a mixture of calcium carbide and a liquid hydrocarbon carrier which is inert to the calcium carbide and free of water through said tubing and said upper packer into said well bore and said formation, wherein the weight ratio of the calcium carbide to the liquid hydrocarbon carrier ranges from one-half pound per gallon to 1 pound per galion;

4. pumping a hydrocarbon through said tubing to force all of said mixture of calcium carbide and a liquid hydrocarbon carrier into said well bore and surrounding formations;

5. pumping an aqueous solution of hydrochloric acid through said tubing and said upper packer and into said well bore and surrounding formation;

6. pumping a liquid hydrocarbon into said tubing to force said calcium carbide, said hydrocarbons and said aqueous solution of hydrochloric acid into said formations surrounding said well bore, said calcium carbide and said aqueous solution of hydrochloric acid then being in reactive contact, wherein the concentration of the aqueous solution of hydrochloric acid ranges from 1 to 28 percent selected from the group consisting of gelled kerosene,

by weight, and wherein the volume rat o f th light naphthas, gasoline, and crude and refined oil havaqueous solution of hydrochloric acid to the calciing an A.P.l. gravity of from 12 to 25.

m Carbide ranges from 1 l 2 gallons P P 4. The method of claim 2 where the hydrocarbon is and 5 selected from the group consisting of gelled kerosene, Securing Said tPbing to Prevent escape of i reac' light naphthas, gasoline, and crude and refined oil havtants, the calcnim carbide and water reacting exing an ARI. gravity Offmm 12 to 25.

othermally to yield gaseous acetylene and lime, the The process ofclaim 1 further comprising exothermic heat of reacting melting any paraffins and oil residues present and the pressure of the gaseous acetylene breaking any hydrocarbon and water emulsions present and cleaning the formation, the hydrochloric acid accelerating the calcium carbide-water reactions and in situ reacting with the lime to thereby avoid lime deposits in the 15 formation.

3. The method of claim 1 where the hydrocarbon is 8. permitting the reaction to proceed for from about 4 to about 12 hours prior to returning the well to production status.

6. The process of claim 2 further comprising 8. permitting the reaction to proceed for from about 4 to about 12 hours prior to returning the well to production status.

Claims

2. inserting tubing through the upper packer;
2. A method for reworking and cleaning a previously fractured and acidized well comprising the steps of
2. inserting tubing through said packer;
3. pumping a mixture of calcium carbide and a liquid hydrocarbon carrier which is inert to the calcium carbide and free of water through said tubing and said packer into said well bore and said formation, wherein the weight ratio of the calcium carbide to the liquid hydrocarbon carrier ranges from one-half pound per gallon to 1 pound per gallon;
3. pumping a mixture of calcium carbide and a liquid hydrocarbon carrier which is inert to the calcium carbide and free of water through said tubing and said upper packer into said well bore and said formation, wherein the weight ratio of the calcium carbide to the liquid hydrocarbon carrier ranges from one-half pound per gallon to 1 pound per gallon;
3. The method of claim 1 where the hydrocarbon is selected from the group consisting of gelled kerosene, light naphthas, gasoline, and crude and refined oil having an A.P.I. gravity of from 12 to 25.
4. The method of claim 2 where the hydrocarbon is selected from the group consisting of gelled kerosene, light naphthas, gasoline, and crude and refined oil having an A.P.I. gravity of from 12 to 25.
4. pumping a hydrocarbon through said tubing to force all of said mixture of calcium carbide and the liquid hydrocarbon carrier into said well bore and surround formation;
4. pumping a hydrocarbon through said tubing to force all of said mixture of calcium carbide and a liquid hydrocarbon carrier into said well bore and surrounding formations;
5. pumping An aqueous solution of hydrochloric acid through said tubing and said upper packer and into said well bore and surrounding formation;
5. pumping an aqueous solution of hydrochloric acid through said tubing and said packer and into said well bore and surrounding formation;
5. The process of claim 1 further comprising
6. The process of claim 2 further comprising
6. pumping a liquid hydrocarbon into said tubing to force said calcium carbide, said hydrocarbons and said aqueous solution of hydrochloric acid into said formations surrounding said well bore, said calcium carbide and said aqueous solution of hydrochloric acid then being in reactive contact, wherein the concentration of the aqueous solution of hydrochloric acid ranges from 1 to 28 percent by weight, and wherein the volume ratio of the aqueous solution of hydrochloric acid to the calcium carbide ranges from 1 to 2 gallons per pound; and
6. pumping a liquid hydrocarbon into said tubing to force said calcium carbide, said hydrocarbons and said aqueous solution of hydrochloric acid into said formation surrounding said well bore, said calcium carbide and said aqueous solution of hydrochloric acid then being in reactive contact, wherein the concentration of the aqueous solution of hydrochloric acid ranges from 1 to 28 percent by weight, and wherein the volume ratio of the aqueous solution of hydrochloric acid to the calcium carbide ranges from 1 to 2 gallons per pound; and
7. securing said tubing to prevent escape of said reactants, the calcium carbide and water reacting exothermally to yield gaseous acetylene and lime, the exothermic heat of reacting melting any paraffins and oil residues present and the pressure of the gaseous acetylene breaking any hydrocarbon and water emulsions present and cleaning the formation, the hydrochloric acid accelerating the calcium carbide-water reactions and in situ reacting with the lime to thereby avoid lime deposits in the formation.
7. securing said tubing to prevent escape of said reactants, the calcium carbide and water reacting exothermally to yield gaseous acetylene and lime, the exothermic heat of reacting melting any paraffins and oil residues present and the pressure of the gaseous acetylene breaking any hydrocarbon and water emulsions present and cleaning the formation, the hydrochloric acid accelerating the calcium carbide-water reactions and in situ reacting with the lime to thereby avoid lime deposits in the formation.
8. permitting the reaction to proceed for from about 4 to about 12 hours prior to returning the well to production status.
8. permitting the reaction to proceed for from about 4 to about 12 hours prior to returning the well to production status.