US1407873A - Sealing off fluids in boreholes for oil wells - Google Patents

Description

C. H. LIEDBECK.

SEALING oFF mums 1N BoREHoLEs FOR olL WELLS.

APPLICATION FILED APR-2. 192i.

1,407,873, Patented Feb. 28, 1922 11u/em n JZL iedbeak,-

AWS.

Fig. 1 the manner in which the process has 'hitherto been performed and in Figs. 2 and Sthe` manner in I jformed according `50.J E l "numerals, indicate the 'time of its setting,

UNITED" STATES PATENT oFFicE.

CARL HENRIK LIEDBECK, OF- GOTTENBOBJG, SWEDEN.

. SEALING OFF Liemeer..

Specicatioii of Lettersjlatent.

FLUiDs`1N BoREHoLEs ron. .oIL WELLS.

Patented Feb. 28, 1922.

Application led April 2,51921. "Serial No. 458,100.

have invented certain new and use Improvements in Sealing Off Fluids in Boreholes for Oil Wells, of which the following is a specification. l y

"This invention relates to ythe process of placing cement between the casing or casings inserted in oil-wells and the surrounding ground by means of iirst introducinov mud or a mixture of clay or other relativegly impervious, substance and water or other liquid between the casing and vthe surrounding ground, and afterwards to introduce cement, hydraulic cement or other hardening substance with corresponding or similar qual ities through holes or openings made in the wall of the casing or casings into the space between the casing or casings and the surrounding ground. 'In this description with the claims all the pipes and tubes, inserted in the borehole in order to prevent the caving in of the ground, are called casings.

It has hitherto been the practice when cementing oil-wel s through holes ory openkings made in the wall of the casing or casings,.first to clean the space between the casing and the surrounding ground also the respective walls of the casing and the ground b aiid afterwards to introduce cement through these holes o r openings made in the wall of the casing or casings into the space between the casing or casings and the surrounding ground. This method has the disadvantage of admitting circulation of liquids `or gases froml one stratum to another or to the open air by means of the free open space between the casing and the surrounding ground, thereby disturbing the cement at the thus preventing it from becoming a hard mass.

The accompanying` drawing illustrates4 in whichthe process is perto the ,present invention. gures the same reference same parts.

Fig', l1y is afschematic vertical section of In `the -*several ushing clear water through this space V also beiilled with `and now no circulation of fluids After this v a borehole.

water-stratum, 4 and Gare impervious strata and 5 is an oil-stratum. 7 is a casing inserted into the impervious stratum 4 in order to shut oi the water iiowing from stratum 2. The borehole has been drilled deeper down into 'the oil-bearing stratum -5 and the well completed by setting a casing 8 down into this oil-stratum in order'' to maintain a clearpassage forthe exploitation of oil from stratum 5. Water: instead of oil will, how ever, be pumpedito' the surface of the ground, showing that casing 7 has failed to shut o the water from above at stratum 4. ln order to shut oli' this water it has been practised l E 1 and 3 are groups of different strata 1n the ground drilled through, 2 is a to drill holes 9' through casings 7 and 8 opposite stratum 4 and through these holes to4 pump clear water in order to clean the outer wall of the `casing 7 and the wall of the borehole and afterwards to pump cementI grout through these holes 9 in order to fill the open space between the wall of the borehole in stratum 4c 4and casing 7. 4But the current of the water prevents the hardening of the cement and'water flows down uninterrupted,

driving the oil in stratum 5 away from the borehole. 10 shows the surface of the water in the borehole. Arrows 15 and 16 indicate the iow of water from one ,stratum te another.

Fig. 2 is av schematic vertical section of the same borehole, showing how the cementing process is proposed to be done according to the present invention. Through the holes 9 it is proposed to pump a mud-laden fluid filling the open space between the wall of the ground and casing 7 and also the space between casings 7 and 8. The borehole should mud-laden fluid. In both cases the surface of the mud-laden fluid is indicated by 11.

Due 'tot the hydrostatic pressure of the mud-laden fluid on the wall of the borehole sol and the sl'dwness with which the water from this mud-laden iiuid pevrcolates into the wall of the borehole, all of the res ctive layers of the ground are/being sea ed oif from one stratum to anothe Yis possible. has been done, it "i prpposed to pump cement grout -through these-hols, whichv cey causing a strong casing 1 and stratum 4.

, afterwards ment partially displaces the mud-laden fluid between the casing 7` and the wall of the borehole. New no circulation of fiuids disturbs the cement at thevtime of its hardening, and the cement becomes a hard mass.

Furthermore it could happenthat when cement grout is displacing the mud-laden fluid between casing 7 and the wallof the borehole at thstratum 4, this cement grout sinks down below stratum 4, thereby not To prevent such a calamity it is proposed first to fill the space between casing 7 and the hole and the space inside casing 7 with mudladen fiuid as the surface 11 indicates, and to' pump a plastic substance through holes 9 between casings 8 and 7 and the wall of theborehole thereby partially displace the mud-laden fluid and afterwards to pump. cement grout into this plastic substance, thereby driving part of this plastic substance below holes 9, thus preventing the cement grout from slnking down below stratum 4. he cement grout will "now harden thus making a strong tight joint between the casings 8 and 7 and the wall of the borehole at stratum 4.

. Fig. 3 is a schematic vertical section of the same borehole after all the mud-laden fluid inside casing 8 has been taken away and exploitation of oil from stratum 5 has begun.

he arrows 17 indicate the flow of the oil from stratum 5 into wall of the borethe borehole with 14 inf dicating the surface of the oil standing in the borehole.

What I claim as new and desire to secure by Letters Patent of the United vStates is Process of sealing ofl'l fluids occurring in boreholes for oil-wells, consisting in filling the spaces between the Wall of the borehole and between casings inserted therein with a 'mud-laden fluid, causing through holes in the casings a hardening substance to partially displace the said mud-laden fiuid and to contact any impervious stratum near the oil-stratum and the casings inserted therein and allowing the hardening @substance t harden.

2. Process of sealing off fluids occurrnig in boreholes for oil-wells consisting in filling the spaces between the wall .of the borehole and between casings inserted therein with a mud-laden fluid, causing through holes in the casings a more plastic substance to partiallydsplace thesaid mud-laden fluid and to contact any impervious stratum near the oil stratum, causing i`n a similar manner a hardening substance to partially displace said plastic substance and to contact said' impervious stratum and the said casings inserted therein, and allowing the hardening substance to harden.

In testimony whereof I aflix my signature in presence of two witnesses.

CARL HENRIK LIEDBECK. Witnesses:

HELGE ANDERssoN, INEz SwENsoN.

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