US2087297A

US2087297A - Method of shutting off water sands in wells

Info

Publication number: US2087297A
Application number: US17995A
Authority: US
Inventors: Thomas W Pew
Original assignee: Individual
Current assignee: Individual
Priority date: 1935-04-24
Filing date: 1935-04-24
Publication date: 1937-07-20
Anticipated expiration: 1954-07-20

Description

July 20, 1937. T. w. PEW

METHOD OF SHUTTING OFF WATER SANDS IN WELLS Filed April 24, 1935 OllSand.

wATli f ThomasMPe Patented July 20, 1937 UNITED. STATES PATENT OFFICE METHOD or SHUTTING OFF WATER SANDS m WELLS My invention relates to methods oi closing off the entrance of water to an oil or gas well from water sands adjacent the oil and gas sands.

In the drilling of wells for oil and'gas it is the usual custom to drill the well down to producing sand and set a casing above the sand and then drill thru into the oil or gas sand. In doing this it rather frequently happens that the bit penetrates water sands adjacent to the oil and gas sands so that water coming into the .well from the said water sands mixes with the oil from the oil and gas sand and interferes with the flow of the oil from the well, and in many cases practically kills the well so that it will no longer Where the well is drilled through the producing sand into water sand below the oil and gas sand it has been common to introduce cement into the well to fill the same up above the water 20 sand so as to close oil the water. Thus a cement plug is formed in the bottom .of the well extending up somewhat above the level of the water sand and so filling the well that no water can enter. This use of a cement plug is only temporarily successful for the reason that water will gradually seep upwardly around the cement plug and finally get access to the oil and gas stratum and eventually flow in in suificient volume to kill the well.

30 It is an object of my invention to provide a method of cementing off the water sands so that they will be closed against the entrance of water therefrom to the well bore and the seeping of the water around the cement into the well will 35 be avoided;

I desire to introduce cement into the water stratum and force the same deeply into the sands around the well bore and by filling up the pores and interstices in the water sand adjacent the 40 well bore to thus prevent the entrance of water to the well or to the oil and gas sands adjacent thereto.

The method may be employed wherever water bearing strata a"e encountered in the drilling of 5' the well.

In the drawing herewith, Fig. 1 is a central vertical section through a well equipped with the usual casing and tubing.

Fig. 2 is a similar view showing the lower end 50 of the apparatus with the water sand cemented off.

In the drawing I have shown a situation in an oil well wherein my invention may be carried out.

I have shown the well I as extending downwardly 55 through the overlying earth stratum 2, and

during the operation of the well but which may 3 is shown a stratum 4, which may or may not be present, and consists of shale, gumbo, or the like, and below this stratum is a water sand 5. The well is shown as having therein a casing 6 5 at the lower end of which is a casing shoe 1 At the upper end of the casing is a casing head 8 having a laterally extending pipe 9 controlled by a valve l0 through which fluid may enter or pass out of the well. The upper end of the casm ing head is shown as being threaded to receive a bonnet H with a stufiing box l2 at the upper end thereof to seal about the well tubing or flow line l3.

The tubing I3 is shown as being equipped with a cross M at the upper end, said cross having two of its outlets closed by bull plugs IS. The other outlet is equipped with a' pipe IS, with a valve i1 therein, said pipe acting as a flow line also serve as a means of pumping liquid into the well during the carrying out of the invention.

I have found that when the water is pumped into the bottom of the well where both oil and water sands are exposed, the water will penetrate and flow away from the well into the water sand much'more easily than it will penetrate the oil It may be forced into the water sand at a comparatively low pressure which will not be entirely sufficient to force it into the oil sand.

In carrying out my invention therefore I close off thewater sand 5 by filling said sand with cement. I do this by first washing the water sand with clear water and forcing the water radially away from the well bore and into the water sands until the pores and interstices of the sand stratum are opened up and cleaned of material tending to clog the same.

In carrying out this invention I first have the 40 well bore filled with mud or other fluid indicated at E8 of suflicient amount to balance the rock pressure. The tubing or flow line i3 is extended downwardly t a point adjacent the bottom or the well and into the vicinity of the water sand. I introduce water to the bottom of the well through the tubing and raise the column of mud to a point above the water sand and this may be approximately one hundred feet of water in the bottom of the well. The upper end of the well casing is then closed by shutting in the valve l0. Fresh water is then forced in through the tubing under pressure and said water will flow outwardly through the water sands as previously noted. Thisiwashing of the sand is continued for a. suificient period to thoroughly wash the sand around the well bore. The amount of be sufficient to thoroughly permeate the sands surrounding the well bore. The amount'will depend upon the judgment of the'operator and amount might be from fifty sacks. I

After the cement has been pumped into the tubing mud is pumped in. following it to displace the cement out of the tubing and into the water stratum so as to thoroughly penetrate the same on all sides.

During the operation of the cementing, I contemplate moving the tubing l3 up and down in the well so'that the bottom of the tubing is not higher than the top of the water sand,.so as to prevent the cement from hardening around the lower end of the tubing and also to distribute the cement equally in all directions. When all the cement has been displaced from the tubing by the mud, the bottom end of the tubing is raised above the water sand. the pump is shut down, and the valve I0 is opened slightly to operate as a choke and allow the to Sergei-a1 hundred pounds the pump is again started and mud is circulated inthe well for a period of about thirty The water sand will thus be completely closed off so that a continued production of oil and gas from the well thereafter will not be interfered with by the water from the water stratum.

Although I have disclosed my inventionas being carried out where the water sand is below the oil sand, it is to be possible 'to carryout the understood that it is invention even where there is oil sand below the water sand. This is possible where the water is due to a leaky casing or failure of the cement to cut off the water sands above. In each case the process is carried out in practically the. same manner until the water sands have been thoroughly filled with sand and prevents vicinity of the well.

In Fig. 2- I have shown the well as it appears after the cement shown at I9 has penetrated the What is claimed is:

1. A method of closing off water sands from an oil and gas well including, filling the well with mud, introducing water into the lower end of said cement under pressure into the washed water sand and forcing said cement deeply into the water sand radially away from the well bore, and

holding said cement in position until it hardens.

2. A method of closing off water sands from an oil and gas well including, filling the well with mud, introducing water into the lower end of said well to raise the head of mud away from the water sand stratum, closing off the upper end of the well, forcing water under pressure into said water sand and washing the same, pumping fluid cement under pressure into the washed water sand and forcing said cement deeply into the water sand radially away from the well bore, continuing the pressure upon the cement and circulating mud in the well, and then gradually relieving the pressure and cleaning the well, and holding said cement in position until is hardens.

3. In a well having oil and water sands closely adjacent to each other, the method of cutting oil the entrance to the well of water from said water sands, including forcing water under pressure into the water sands to wash the pores and interstices thereof, the pressure being insuflicient to force the water into said oil sand, following said water with fluid cementitious material to fill the said water sand deeply into the water stratum with said cementitious material, holding said cement in said sand until it sets and then washing the well.

4. A method of cementing off water sands in wells comprising forcing water under pressure into said sands to wash the pores and interstices thereof, then forcing hydraulic cement under pressure deeply into said sands to close the pores and interstices thereof, maintaining said cement in position until it hardens, circulating fluid'in' the well until the hole is free of cement and then washing said we 5. The method of closing off the entrance to a well from water producing sands lying adjacent oil and gas sands, which consists in feeding water through a. tube under pressure sufiicient to penetrate deeply-into the water sands but insuf- -ficient to penetrate the oil sands whereby to wash the water sands in the vicinity surrounding the well bore, forcing hydraulic cement through a tube under pressure suflicient to penetrate the washed water sands but insufficient to penetrate the oil sands, and maintaining pressure in the well bore to hold the cement in the water sands until it hardens.

6. In a well having water'producing sands lying adjacent to oil and gas sands, the method of closing off the entrance of water to the well from said water producing sands including feeding water through a flow tube having its lower end in the water sands deeply into the water sands to wash the same in the vicinity surrounding the well bore, forcing hydraulic cement through the flow tube to deeply penetrate the water sands, maintaining fluid pressure in the well bore to hold the cement in the water sands until it hardens, and before the cement hardens raising the flow tube so that its lower end is above the water sands.

'7. In a well having water sands and .oil and gas sands discharging fluid into the bore ofthe well, the method of holding back the oil and gas and permanently closing ofi the water from entrance into the well, which includes filling the well with mud, introducing water under pressure below the mud, keeping the upper discharge end of the well open until the mud is raised by the water to a level above the water sands, closing the upper end of the well so that the mud constitutes a barrier for preventing the escape of the water into the oil and gas sands, continuing the introduction of water into the water sands to wash the same, then forcing liquid cementitious material into the pores and interstices of said water sands to fill the same with said material, and holding the cementitious material in place until it hardens.

8. In a well having water sands and oil and gas sands, the method of closing off the entrance of water to the oil and gas sands including filling the well with mud, introducing water through a flow tube below the mud, keeping the upper discharge end of the well open until the mud is raised by the water to a level above the water sands, closing the upper end of the well so that the mud provides a barrier for preventing the entrance of the water into the oil and gas sands, continuing the introduction of water into the water sands to wash the same, then forcing liquid cementitious material through said flow tube into the pores and interstices of said water sands to fill the same with said material, maintaining fluid pressure in the well to hold the cement in the water sands until it hardens, before the cement hardens raising the flow tube so that its lower end is adjacent, the oil and gas sands, and then releasing the fluid pressure and withdrawing the mud from the well so that the oilland gas may be removed. THOMAS W. PEW..