Method of drilling and completing wells

A method and apparatus for drilling and completing a bore hole is disclosed. Generally, the method comprises the steps of positioning a workstring in the well, with the workstring having attached thereto a bottom hole assembly. The bottom hole assembly may contain a bit for rotary drilling a bore hole; and, a drilling motor, operably associated with the bit, for effecting rotation to said drilling means. The method further includes the steps of circulating a fluid in the workstring so that the motor effects rotation of the bit means; and, drilling the bore hole through a target reservoir. In one embodiment, the workstring string is a production string, and the production string is attached to an isolation safety valve member for isolating the well and the bore hole from pressure.

FIELD OF THE INVENTION 
The present invention relates to drilling and completing of wells. In 
particular, but not by way of limitation, the invention relates to 
drilling and completing of hydrocarbon wells. 
BACKGROUND OF THE INVENTION 
In order to recover hydrocarbons, a well is drilled into the ground until a 
hydrocarbon reservoir is encountered. In the earlier days of oil and gas 
exploration, most well sites were located on shore, and the wells that 
were drilled were primarily vertical. As the search for larger hydrocarbon 
reservoirs continues, the exploration is now focusing on offshore 
locations and remote land sites. Further, many wells are being drilled and 
completed as highly deviated and horizontal wells for economical and 
logistical reasons. 
In offshore waters, one type of installation includes use of a fixed 
platform wherein the legs of the platform are rigid and embedded into the 
sea floor. The fixed platform has been a very popular type of structure; 
however, as the search for reserves continues, oil and gas companies find 
themselves searching in offshore locations were the water depths may be as 
deep as 6,000'. 
As regards land locations, the exploration, drilling and production are now 
taking place in remote locations that may include arctic regions, desert 
regions, or even the rain forest of Latin America. Regardless of the 
inland or offshore location of these rigs, the remote nature of their 
location and the necessary ancillary equipment and personnel that must 
follow, the rental rates for these rigs are very significant. 
In offshore waters, traditional fixed platforms can not be placed in depths 
generally greater than 300'. Therefore, tension leg platforms, drilling 
ships or semi-submersible drilling vessels are being used to drill these 
deep water wells. Typically, this involves the drilling rig being placed 
on the ship or floater. A sub sea Blow Out Preventor stack (BOP) is then 
placed on the ocean floor. A riser is then connected from the sub-sea BOP 
to the drill floor. The bore hole can then be drilled. 
Once the well has been drilled and a hydrocarbon reservoir has been 
encountered, the well is ready to be completed. Many sub-sea wells are 
completed as single satellite wells producing to a nearby platform. They 
are a means of producing field extremities that cannot be reached by 
directional drilling from an existing platform and where the economics do 
not justify the installation of one or more additional platforms. Some 
multi-well templates and piping manifolds have been installed that go 
beyond the satellite well concept. 
While the governments have recognized the importance and the necessity of 
drilling and completing wells in remote locations, significant regulations 
exist for each phase of the drilling, completing, and producing operation. 
Thus, when a certain size drill string is substituted for a second size, 
or alternatively, for production tubing, operators will require the 
changing of the BOP ram members so that control of the well bore is always 
maintained. This is a crucial concern because control of the well bore is 
essential at all times. 
When the operator is converting from the drilling phase to the completion 
phase, the BOP stack must be changed out to accommodate the different 
outer diameter sized work string--from drill pipe to a production string. 
Furthermore, during the actual completion phase, the production tubing 
must be manipulated in order to perform the necessary functions such as 
perforating, circulating, gravel packing and testing. According to 
established safety procedures mandated by operator rules and government 
regulations, it is necessary to change out the BOP rams during certain 
phases. The changing out of BOP rams can be a costly and time consuming 
practice. Day rates for drill ships and semi-submersible ships can be 
quite expensive, and during the procedure for changing out the rams, no 
other substantive operations can be accomplish. 
In a typical offshore location, wherein the drilling rig is either a 
jack-up vessel or placed upon a fixed platform, the BOP is normally 
situated on the vessel or platform itself. Nevertheless, because of safety 
considerations and government regulations, the control of the well bore 
from blow-out is always of primary concern. Therefore, safety of the 
installation along with economically performing the operation has always 
been a need. 
In order to minimize cost, several techniques have been employed with 
varying degrees of success. One technique has been to drill and case the 
well, and then immobilize the drilling rig. A replacement rig is then 
utilized to complete the well. The replacement rig may vary from a 
snubbing unit, coiled tubing unit, workover rig using smaller inner 
diameter pipe, and in some cases wire line. Thus, rather than completing 
the well with the more expensive rig, a less expensive rig is utilized. 
Therefore, there is a need to provide for a more cost effective means for 
drilling and completing wells in the exotic locations of the world. 
SUMMARY OF THE INVENTION 
A method of drilling, and then completing a bore hole from a cased hole 
well in a single trip is disclosed. The method comprises the steps of 
positioning a work string in the well, the work string having attached 
thereto a bottom hole assembly that will have attached thereto a bit means 
for drilling a bore hole. Also attached will be motor means, operably 
associated with the drilling means, for effecting rotation to the drilling 
means. The method includes circulating a fluid in the work string so that 
the motor means causes rotation of the bit means in order to drill the 
bore hole through a target reservoir. 
In one embodiment of this device, the work string may be a production 
string which may be attached to an isolation safety means, such as a 
Christmas tree, for isolating the bore hole from reservoir pressure. 
In yet another embodiment, the drilling means will contain: orienting 
means, operably connected to the motor, for determining the direction and 
location of the bit means and generating a signal in response thereto; 
logging means for evaluating the lithology of a subterranean reservoir and 
generating a signal in response thereto; and, non-rotating means, operably 
connected on one end to the drill string and on the second end to the 
motor, for imparting selective rotation to the drilling means. 
In this embodiment, the steps of drilling the bore hole will comprise 
transmitting the signals from the orienting and logging means; then, 
plotting the path of the bit means in order to determine the location of 
the bit. Next, the bit means can be steered in response to the bit 
location such that the bit means is drilled through the target reservoir. 
This device may also contain completing means for completing the well, 
which in one embodiment would be preventing means for preventing the 
production of a reservoir sand into the inner diameter of the work string, 
also referred to as screen means. The steps would then include positioning 
the screen adjacent the target reservoir; and, placing a gravel slurry in 
the annulus adjacent to the target reservoir. The preventing means may 
include a soluble compound, and which would require after having the 
preventing means in position, displacing an acid solution means for 
dissolving the soluble compound; and thereafter, placing the well on 
production. 
This bottom hole assembly may also contain a nuclear source means for 
determining the nuclear properties of the subterranean reservoir, and 
therefore, a further step of retrieving the nuclear source means from the 
bottom hole assembly may be necessary. 
An object of the present invention includes the capability of enhancing the 
productivity of the reservoir since the method of drilling and completing 
will allow for use of lighter, cleaner and environmentally safer drilling 
and completion fluids. Still yet another object includes utilizing smaller 
quantities of drilling fluids during the drilling and completion phase 
since the annular area is smaller. 
Another object includes having the drilling and completion means connected 
to the production tubing so that the completion assembly may be drilled 
into place. Still yet another object includes drilling and completing 
directional and multi-bore wells faster, and more economical. 
A feature includes employing a drilling bottom hole assembly that is 
selectively detachable to a work string. Still another feature includes 
the use of an attachment means that can attach, and detach, the bottom 
hole assembly to the work string at the option of the operator. 
Still yet another feature includes the use of gravel packing means on the 
bottom hole assembly which will allow the gravel packing of the well after 
the screen is in place. Another feature includes employing the drilling 
bottom hole assembly and completion bottom hole assembly in tandem when 
the well is being drilled with the work string. 
Yet another feature of this invention includes eliminating tripping in and 
out of the well the drill string and completion bottom hole assembly 
thereby saving valuable rig time. Another feature includes use of a 
soluble compound that surrounds the screen not allowing the screen to 
become clogged with impurities, and also allows for the drilling fluid to 
be circulated through the inner diameter of the bottom hole assembly and 
the fluid flow continues on the outer diameter of the bottom hole 
assembly. Yet another feature includes the optional use of wash pipe in 
the bottom hole assembly which is placed concentric with the screen means 
and can be used as the inner diameter flow path of the drilling fluid. 
An advantage includes use of orienting means while drilling such that the 
operator can steer the bit into the planned trajectory. Another advantage 
includes use of logging means while drilling such that the operator can 
evaluate and coordinate the subterranean reservoirs and telemeter the data 
to the surface. Still yet another feature is that a significant portion of 
the well can be drilled and cased before encountering the target 
reservoir, and thus, it is possible to drill the majority of the well bore 
with environmentally sensitive fluids that can be lighter pounds per 
gallons. Still yet another advantage includes the ability to use 
completion fluids that contain fewer solids, and therefore, expose the 
formation to less formation damage thereby providing for a better 
completion. 
Another advantage includes the ability to complete sub-sea wells without 
changing out the rams of the Blow Out Preventor stack since the work 
string may remain in place after drilling through the target reservoir. 
Still yet another advantage includes having a drilling bottom hole 
assembly attached to a production string such that the production string 
is drilled into the target reservoir, and the well can be placed on 
production without the necessity of pulling out of the hole and replacing 
the work string.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 depicts a semi-submersible drilling vessel 2 that has contained 
thereon a drilling rig 4. A sub-sea Blow-Out Preventor stack 8, also 
referred to as isolation safety means for isolating the well and the bore 
hole from pressure, is positioned on the ocean floor 10, with a riser 12 
linking the sub-sea BOP stack 8 and the surface BOPs 6. Extending into the 
earth from the sub-sea stack 8 will be the well casings, including the 
conductor, surface, and intermediate 14, 16 and 18, respectfully. 
As is well understood by those of ordinary skill in the art, the casing 
strings will intersect various subterranean reservoirs 22, some of which 
may contain hydrocarbons. As is shown in FIG. 1, a target reservoir 24 has 
yet to be drilled through. A work string 20 is positioned within the riser 
12 and casing string 18. The string 20 has attached thereto a bottom hole 
assembly 26 containing a drilling means and sand control means, all of 
which will be discussed in detail hereafter. It should be noted that 
throughout the description of the preferred embodiments, like numbers used 
in the various figures refer to like components. 
Referring now to FIG. 2, the preferred embodiment of this invention which 
depicts the drilling and completing method and apparatus will now be 
described. In FIG. 2, the bottom hole assembly 26 will be attached to a 
work string 202. The work string 202 will contain a packer means 204 for 
sealingly engaging the casing string 206 so that an upper annulus 208 and 
lower annulus 210 is formed. The work string 202 may contain subsurface 
safety valve, and any other necessary nipple setting profiles 214. 
The bottom hole assembly 200 will consist of bit means 218 for drilling a 
bore hole, with the bit means 218 depicted being a tri-cone rotating bit; 
however, it should be understood that other types of bit means, such as 
PDC bits may be employed. The assembly 26 will further consist of a motor 
means 220 for effecting rotation to the bit means 218, which in FIG. 2 is 
a stator 222 and rotor 224 assembly well known in the art. 
The motor means 220 will in turn be connected to the deflection means 226 
for causing a deflection in the bottom hole assembly so that the 
trajectory of the drilling path is curved. While a deflection means 226 
has been shown, the teachings of this invention are certainly applicable 
to vertical hole completions. The deflection means 226 may be of the type 
where the angle of deflection is manipulated at the surface and run into 
the well bore, or alternatively, the deflection means 226, and in 
particularly the angle of deflection, is automatically controllable by 
transmitting a signal down hole by means of mud pulse, or acoustic 
telemetry. Alternately, the deflection means 226 may be controlled by a 
predetermined pressure force exerted on the deflection means 226 through 
either the inner diameter or outer diameter of deflection means 226. 
The non-rotating swivel means (not shown) which is commercially available 
from Baker Hughes Incorporated and sold under the product name Model "A" 
Swivel performs the function of preventing relative rotation of the work 
string with respect to the threadedly engaging packer, thus assuring that 
the left hand packer threads of any production packers disposed on the 
production string cannot be disengaged during the necessary right hand 
rotation of the work string required to set or unset components of the 
bottom hole assembly during the drilling and placement of the sand control 
screen. 
As seen in FIG. 2, the deflection means 226 will be attached to the means 
for preventing sand production 228, which in the embodiment shown is a 
sand control screen means in that there is a segment of perforated pipe 
230 that has disposed about it a wire mesh screen 232. A soluble means, 
disposed about the sand control means 228, may be added for preventing the 
contamination of the sand control means from the drilling fluids and 
cuttings encountered during the drilling, placement, and completion of the 
well. Since the screen means 228 is porous, the soluble means can also 
serve the purpose of forming an impermeable barrier thereby allowing the 
circulation of the drilling fluid down the inner diameter of the 
workstring 202, out the bit means 218 and up the outer diameter of the 
workstring 202. The soluble means may be removed by acid treatments. The 
soluble means may be a wax composition; however, other types of compounds 
are available. The actual soluble means employed will depend on down hole 
temperature, and wellbore fluid composition. 
Other types of preventing means can be employed such as a slotted liner 
well known in the art. The inner diameter of the sand preventing means 
228, as well as the inner diameter of the remainder of the bottom hole 
assembly is denoted as 233. The detaching means 234a for detaching the 
preventing means 228 from the deflection means 226 and the remainder of 
the bottom hole assembly 200 is a releasable mechanism means that has 
contained thereon engaging collet members 236a that is well known in the 
art such as those devices used to release tubing conveyed perforating 
guns. The detaching means 234 is commercially available in the form of 
Mechanical and Hydraulic Release Subs from Baker Hughes Incorporated. A 
second detaching means 234b for detaching the work string 202 from the 
bottom hole assembly 200 is also shown, which has contained thereon 
engaging collet members 236b. 
With reference to FIG. 3, the bottom hole assembly 26 is depicted wherein 
the bottom hole assembly 26 is in the process of drilling to a target 
reservoir 242. In the embodiment shown, the work string 202 is a 
production tubing string even though other types of conduits could be used 
such as coiled tubing. 
Thus, for drilling to occur as shown in FIGS. 3, a drilling fluid is pumped 
down the inner diameter 240 of production tubing 202, through the inner 
diameter 233 of the sand control means, and into the motor means 220 
thereby effecting rotation of the bit means 218. As can be seen, the 
production tubing 202 is the drilling conduit, and the cuttings and 
circulation of the drilling fluids follow the path of the annulus 208, 210 
in the open hole section as well as the cased hole section. 
While not depicted in the drawings, it is possible to include in the bottom 
hole assembly 200 an orienting means, operably associated with the motor, 
for determining the direction and location of the bit means and generating 
a signal in response thereto. Also, logging means for evaluating the 
lithology of a subterranean reservoir and generating a signal in response 
thereto, and non-rotating means, operably connected on one end to the 
drill string and on the second end to said motor, for imparting selective 
rotation to the bit means may also be included. 
In order to drill and complete to the target reservoir 242, the procedure 
first comprises pumping a drilling fluid down the work string 202 thereby 
effecting rotation of the drilling means 218; next, orienting means and 
logging means will generate a representative signal, and that signal will 
be transmitted to the surface. The path of the bit means 218 may then be 
plotted in order to determine the location of the bit. The driller can 
then steer the bit means in response to the bit location, and ultimately 
drill through a target reservoir 242 with use of the bit means 218. 
FIG. 4 depicts a bore hole that has been drilled such that the target 
reservoir 242 has been encountered and the bore hole drilled to a 
sufficient depth so that the sand prevention means 228 is adjacent the 
target reservoir 242. 
Referring to FIG. 5, the method and assembly of the present invention also 
provides for the placement of a gravel pack slurry in the annulus 210 
adjacent the target reservoir 242. The workstring for this particular 
embodiment will contain the previously described bottom hole assembly 26 
that includes the motor means 220, bit means 218, and the screen means 
228. In order to place a gravel slurry into the annulus 210, it is also 
necessary that bottom hole assembly 200 also contain a gravel pack 
extension and crossover tool means 260 well known in the art and 
commercially available from Baker Hughes Incorporated under the trade name 
Model "S-2" Cross-Over, and the "S-1" Gravel Pack Extension. 
The gravel pack extension and crossover tool means 260 will contain a 
sliding sleeve 262 that is slidable from a closed position to an open 
position, and is generally actuated by dropping a ball (not shown) from 
the surface, with the ball resting on the sliding sleeve 262. By 
pressuring up on the internal diameter of the work string, the ball will 
force the sleeve to an open position. 
As seen in FIG. 5, the entire bottom hole assembly 26 is connected to a 
packer means 266 that will sealingly engage the casing string 206 so that 
an upper annulus 208 and a lower annulus 210 are formed. The packer means 
266 will have operatively connected thereto a setting tool 267, with the 
associated wash pipe 268 extending therefrom, with the entire assembly 
being well known in the art and commercially available from Baker Hughes 
Incorporated under the trade name "SC" Setting Tool, or alternatively, the 
"BDP" Setting Tool may be used. 
One of the functions of the wash pipe 268 is to serve as a conduit for the 
drilling fluid during the drilling phase. Thus, the path of the fluid 
during drilling is through the inner diameter of the work string 202, 
through the packer means 266, into the inner diameter of the wash pipe 268 
and through the motor means 220 when the wash pipe 268 is used, it is not 
necessary to place the soluble compound about the screen 228. 
The packer is released from the wash pipe and setting tool by rotating the 
workstring 202 so that the setting tool 267 and wash pipe 268 disengage by 
the disengagement via the threads at 269; thereafter, the setting tool 267 
may be picked up which in turn lifts the wash pipe 268 which had been 
previously stung into the top of the motor means 220. The entire wash pipe 
assembly 268 is lifted up so that the end of the wash pipe 268 is adjacent 
the screen means 228 (not shown). In this position, the well can be gravel 
packed. As previously mentioned, the sliding sleeve 262 had been opened, 
thus, once the wash pipe is in the proper position, the gravel packing 
process may begin and the sand slurry is pumped down the inner diameter of 
the work string 202. The sand slurry exits into the annulus 210 at ports 
264 and 265 into the annulus 210. The fluid of the sand slurry will be 
returned through the porous sand screen 228 and into the bottom of the 
wash pipe 268, and then up through the inner diameter of the wash pipe 268 
and is ultimately crossed-over to the annulus 208. Once the necessary 
quantity of sand has been pumped, the workstring 202, setting tool 267 and 
wash pipe 268 can be removed from the wellbore. Afterwards, the production 
string is run into the wellbore, with the production string being stung 
into the top of the packer means 266. Hydrocarbons from the reservoir 242 
may now be produced through the sand screen 228 and up the inner diameter 
of the production string. 
Referring now to FIG. 6, an alternate embodiment of the present invention 
is depicted that can be used when gravel packing is desirable. The bottom 
hole assembly 26 including the screen 228, motor means 220 and bit means 
218 is essentially the same as those depicted in FIGS. 2, 3, and 4. With 
the modifications to be described, it is now possible to circulate gravel 
pack the well annulus 210. Specifically, the embodiment of FIG. 6 depicts 
a production type of packer means 274 that will be connected to the 
production work string (not shown). The packer means 274 is commercially 
available from Baker Hughes Incorporated under the name Retrievable 
Hydraulic Set Packer. Extending downward from the production packer 274 
will be the over shot means 276 for landing the packer means 274. The 
remainder of the bottom hole assembly 200 is identical to the bottom hole 
assembly 26 described in FIGS. 2, 3, and 4. 
Thus, the procedure for drilling, completing and gravel packing the 
hydrocarbon reservoir 242 utilizing the embodiment of FIG. 6 would include 
drilling through the target reservoir 242 as previously described with the 
bottom hole assembly depicted in FIG. 3. Once the screen means 228 is 
adjacent the target reservoir 242, the annulus 210 can be gravel packed by 
circulating a gravel pack slurry down the annulus 208 and getting the 
fluid returns through the screen means 228. The reason for not placing the 
packer means 274 on the original bottom hole assembly is that the outer 
diameter of the packer means 274 is too large, and therefore, the gravel 
slurry could not be effectively placed down hole without the slurry 
bridging about the packer 274. 
After placement of the gravel slurry, the work string is detached from the 
remainder of the bottom hole assembly 26 utilizing the detaching means 
234b that is positioned above the screen means 228 as previously described 
in FIG. 3. As shown in FIG. 3, the detaching means 234b has contained 
thereon engaging collet members 236b that is well known in the art such as 
those devices used to release tubing conveyed perforating guns. The 
detaching means 234b also contains a nipple profile. The detaching means 
234B is commercially available in the form of Mechanical and Hydraulic 
Release Subs from Baker Hughes Incorporated. The detaching means 234 is 
not shown in FIG. 6 since the assembly shown is after the detachment and 
removal of the workstring from the wellbore and the packer means 274 has 
been subsequently lowered into the wellbore on the production string. 
Once the detaching means and work string have been pulled from the 
wellbore, the outer diameter nipple profile 277 with the rest of the 
bottom hole assembly 26 remains within the wellbore. Next, a production 
tubing string is run back into the wellbore, with the production tubing 
string having the previously mentioned packer means 274 and the over shot 
means 276 extending therefrom. The over shot 276 will be stung into and 
attach with the previously mentioned outer diameter nipple profile 277. 
Once the over shot is placed within the nipple profile 277, the packer 
means 274 is set against the casing string by hydraulic means such as 
pressuring up on the annulus. After the packer is set and an upper annulus 
208 and lower annulus 210 is formed, the well may then be placed on 
production. 
Changes and modifications in the specifically described embodiments can be 
carried out without departing from the scope of the invention which is 
intended to be limited only by the scope of the appended claims.