US105590A - Improvement in treating oil-wells to remove obstructions to the flow of oil - Google Patents

Description

' within the well.

UNITED STATES PATENT BUTLER e. NOBLE, on BROOKLYN, NEW YORK.

IMPROVEMENT IN TREATING OIL-WELLS TO REMOVE QBSTRUCTIONS TO THE FLOW OF OIL.

Specification forming part of Letters Patent N0. 105,590, dated July 19, 1870.

Mode or Process for Increasing the Yield of Petroleum-Oil Wells and I do hereby declare that the following is a full and exact descrip- 1 tion, to wit:

The nature'of my invention consists in removing paraffine or other obstructing matters] from the seams, issues, or natural ducts of such wells by the employment of an intense: productive points and continuous heat at the To enable others skilled in the art to adopt and use my invention, I will proceed to describe the mode by which I accomplish the results desired.

I Petroleum-oil wells are bored inthe rock formation to a depth of from two hundred to one thousand feet, and are from three to six inches in diameter. Inthe oil regions of Pennsylvania the oil is found in the sand-rock. These sand-rocks occur inseparatestrata and ing oil-wells know these points of oil-inflow,.

and, by record kept when the well is bored,

can determine with accuracythe location and extent of all water-courses, gas-flows, and oilflows. The average range of inflow does not exceed twenty feet of vertical extent.

Many wells, after yielding oil in large quantities, gradually diminish in productiveness,

and ultimately cease to produce in paying.

quantities. This failure in yield is not always because of exhaustion of supply, but results from the clogging up of the seams or natural ducts leading into the well-bore by the deposition of paraffine and perhaps other carbonaoeousmatters. Paraffine is of wax-like struct- These scams or in-' ure, about the consistency of spermaceti. It

melts at a temperature considerably below the boiling-point of water. It is produced from petroleum by deposition at low temperature.

It is probablethat the carbureted-hydrogen gas, almost always present in oil-wells, is under pressure within the cavities of the rock, and when it reaches the vicinity of the wellbore it gradually expands, and of course produces a low temperature, favorable to the. deposition of paraffine.

It is obvious that these depositions must be for the most part in the apertures of the oildncts, within the well or immediately contiguous thereto. Portions of paraffine brought up by the pump often have the imprint and form which indicate this location.

To remove these obstructions and restore the yield of oil, many modes have been devised. That which is now generally adopted consists in pouring into the well from six to sixty barrels of naphtha or other light hydrocarbon for the purpose of dissolving the paraffine. The method is attended with some success, and hundreds of wells are kept alive by a weekly dose. The disadvantage is the expense and labor, and as all the naphtha must be pumped out, mingled with the natural oil, the latter is made of less value. Again, if water be present in sufficient amount to cover wholly or in part the range of inflow, the naphtha fails to reach the points desired. The presence of water also in small quantities materially aifects the solvent power of these agents.

Attempts have been made to introduce steam and to force hot air into the well.

These modes involved massive machinery and great expense. The wells have usually many hundred feet of water, and the heat would be taken up and lost by the well and its contents long before the points of obstruction were reached, and hence this method pro duced no favorable results.

The torpedo for exploding gunpowder, nitroglycerine, and similar matters for the purpose of shattering the well-walls and enlarging the cavity, and thus removing obstructions or making new seams or issues, has been used with varied results. The violent ruptureof the surrounding walls may open new fissures,

but the chances are equal that it would close up the old. Hence, though the production is often increased by this mode, yet wells have been destroyed and ceased to produce when subjected to this violence.

The use of nitro-glycerine, dynamite, or other highlyexplosive agents is always attended with risk and danger.

The principal and distinguishing characteristic of my invention is the removal of paraffine and other matters from the seams, issues, or inflows of the oil-well by the combustion of slow-burning compositions, so disposed as to produce an intense and continuous heat without explosion at the points within the well where these obstructions occur. To eflect this I construct what I denominate a volcanic case. These cases are usually of wroughtiron, though other metal or material may be used. The case is cylindrical in form, of any convenient length, and of such diameter as the size of the well requires. There should be an annular space of about one inch around the case when placed within the well. A well of five -inch bore would require a volcanic case of about three inches diameter. The wells often contain four or five hundred feet of water, and cases must be of sufficient strength to withstand the pressure. The bottom of the case must be closed, and the top provided with a cap, which is fixed when the case is filled. Near the bottom I make from three to six lateral vents. The size will vary with the amount of heat required in a given time. In general, the total area of the ventaperture should be much less than the area of burning-surface within the case.

The case is filled with a slow-burning compound analogous to that employed for filling rockets, and well known to persons skilled in pyrotechny. Common granulated gunpowder, reduced to a fine powder, forms a safe and reliable filling. It may be made slower by the admixture of five to twenty per centum of powdered charcoal. Compounds of nitrate of soda or nitrate of potash, sixteen parts, and powdered charcoal, six parts, form a good filling. I do not confine myself to any definite composition in the production of such compounds, as they are of great variety and well known.

The filling should be well rammed to insure slow and even combustion and to render explosion impossible. The action of slow'burn- 111g compounds is unlike that of granulated gunpowder or nitro-glycerine. While the hot gases produced are identical, the one evolves immense volumes instantaneously. The other, burning slowly, may produce an intense and continuous heat for a long time, and can hardly be said to be explosive.

Carefully-conducted experiments have demonstrated that slow-burning compounds analogous to rocket filling, well rammed in cases with small apertures or vents, will, when ignited, exert a pressure of many thousand pounds to the inch, and produce a heat at the ure of the hot gases.

points of discharge equal to from 600 to 1,200 Fahrenheit, and yet there is no explosion, the case being strong enough to resist the press- The case when filled is closed securely and made tight and impervious to water. The vents are closed externally by placing over them small patches of metal or other hard substance, and well secured against moisture by wax, rubber, or other suitable material.

For igniting the charge I employ any of the ordinary and well-known modes used for ignitin g cartridges or blasts under water. Fulminates placed within the case at the bottom may be fired by friction, but I prefer electric fuses for safety and certainty. The ignition should take place at the bottom of the case. An electric fuse may be inserted through one of the vents, and properly connected with voltaic battery or electric apparatus. The connections should be adequately protected against wet to secure insulation. The volcanic case, properly prepared and connected, is let down into the well by a line properly attached to a point immediately below the range of inflow 5 it is then ignited. As soon as combustion takes place the patches are thrown off and the red-hot gases issue with great force from the lateral vents, impinging direct against the well walls, displacing the water. The volcanic case is now, while burning, moved slowly upward, exposing the interior surface ofthe well-bore continuously to the action of the blast until the upper limit of the range of inflow is reached, after which, if not exhausted, the case may be slowly lowered to the place of beginning, and thus by moving upward and downward the whole range of inflow is subjected to the intense heat.

All aggregations of paraffine must be melted and removed. The force of the blast, especially if aided by the pressure of several hundred feet of water, is such as to render the heat effective within and through the fissures and seams of the rock for many feet distant.

All matters which are fusible will be eliminated. The old issues may be enlarged by the intense heat and great pressure, and even new or imperfect ones developed and the way prepared for a more abundant returning oil-flow.

The advantages of the volcanic mode of treating oil-wells are many and clearly apparcut. The expense is comparatively trifling. The material for filling the cases is cheap, easily prepared, and safely transported and handled. The case can be used many times. For most wells a case of three inches diameter and three feet in length will burn for from six to eight minutes, a time amply sufficient to command the whole extent of inflow.

. I V w 1 I do not confine myself to the particular form of volcanic case herein described, as many a other forms might serve equally well,'nor to troleuni-oil wells, substantially as herein described.

2. The use of slow-burning compositions Without explosion for the removal of paraffine and other obstructing matters from the seams, issues, or inflows of petroleum-oil .Wells, substantially as herein described.

BUTLER G. NOBLE.

Witnesses W. G. SPENCER, W. WATERs.