Drilling

October 22, 2009 - Pétrolia (PEA-TSXV) announces that it has just successfully completed drilling of the Pétrolia Haldimand No. 2 confirmation well. The well, which reached a depth of 1,200 meters, intersected a 474-meter zone mainly composed of sandstone saturated with light crude oil. Two of the intervals examined show the presence of a high concentration of parallel, sub-vertical open fractures which seem to be fed by matrix porosity. In view of these encouraging results, the well was cased down to its full depth of 1,200 m KB. A service rig will be mobilized in the near future to carry out production tests on the zones of interest.

Further work

Following these results the well was cased to its full depth of 1,200 m KB and the drilling rig was released on October 15th. A service rig will be mobilized in the near future to carry out production tests on the zones of interest.

Meanwhile, data from the Pétrolia Haldimand No. 1 and No. 2 wells as well as the 3-D seismic data will be studied by Sproule Associates of Calgary. Other firms specialized in fractured reservoirs may also be consulted. These firms will be charged with:

• recommending a work program for the final design and execution of production tests on the Pétrolia Haldimand No. 2 well;
• estimating the volume of petroleum in situ and the recoverable reserves;
• suggesting the most appropriate methods for the development and exploitation of the deposit.

The traditional tool to drill a well is the tricone wicht has three rotary cones, fitted with steel or tungsten carbide teeth. The drill bit crushes the rock and allows drilling of the well. The rotary table, located on the surface on a drilling rig, is a mechanical device that provides clockwise rotational force to the drilling tool through the drill pipes. The drill pipes are also used to circulate drilling mud into the borehole. The mud has  tree main functions:

• Facilitate the action of the tricone (drilling bit) by hydraulic jet effect.
• Ensure the continuous removal of cuttings (rock chips) generated by the bit during drilling of the well;
• Exercise, by its weight, a counter pressure against the hole walls so that formation fluids contained in porous rock remain in place. This counter pressure should avoid hydrocarbons coming uncontrolled to surface (blow out).
  

Bit Change

Even if they are made from top quality materials, the bits eventually wear out, and must be replaced from time to time. The team then suspends the drilling operation proper and pulls out the drill pipes out of the hole. Each drill pipe joint measures about 9 m. The drill pipes are pulled out of the hole and stored in the drilling mast (derrick) as one, two or three joints (9, 18 or 27 m) depending on the size of the derrick.  A drilling rig will thus be described as single, double or triple.
We can easily understand the benefits of a large drilling rig when considering that for a 2 000 m well, the drilling team of a "single" rig has to unscrew and screw the drill pipes together about 400 times to change a bit, whilst on a double rig, it would do that only 200 times and only 133 times on a triple.

Once the surface hole has been drilled (~210 m), the rig workers tear down the annularBOP and the diverter in order to run the surface casing. This operation entails:

• lowering in the hole a 311 mm diameter steel pipe (the casing);
• cimenting the outside of the casing from surface to the total depth (~210 m)

It is on this casing that will be installed the blowout preventers which will allow the control of any unexpected flow of fluid from the formations.

Once the drilling site has been prepared and the equipment
is in place, it still remains to:

• Raise the derrick and perform a final levelling of the substructure to position the derrick in vertical alignment with the well.
• Assemble the rotating head (used to inject drilling mud in the drill string) and the kelly (a pipe with a square or hexagonal cross-section, used to impart rotation to the drill string and drilling bit).
• Mix the drilling mud which will be used to return to surface the drilled cuttings

These steps completed, the actual drilling of the well can begin. Once underway, drilling operations will continue 24 h/day, 7 days/week with two (2) 12-hour shifts.

The Pétrolia Haldimand N°2 was spudded on Friday September 18, 2009, at 08h55. (Cf. the September 18, 2009 press release).

The road transport and rig-up of a drilling rig are essentially a question of logistics. Even for a medium size rig, with a 3600 m drilling rating and the capacity to pull and rack the drill pipe in double joints (±18 m each), one can expect to need 25 to 30 semi-trailers loads. Although the number of loads is not a problem per se, the dimensions of these loads require special attention.

Once on location however, the rig-up of the equipment proceeds rapidly. Although each piece of equipment has to go to a specific spot in relationship with the well itself, the equipments are designed to tie-into one another with flexible connectors. The main elements of a drilling rig are, in broad order of installation:

• the mats used to spread the weight of the drilling rig,
• the sub-structure,
• the drawworks,
• the derrick,
• the mud tanks,
• the mud pumps,
• the electrical generators,
• the workshop and stores,
• the fuel and water tanks,
• the drill pipe tubs
• the crew’s change room and boiler (for winter operations)

In addition to these equipments, which are specific to the drilling operations, one normally finds on a drilling site a number of trailers which are used by the personnel which provide continuous supervision of operations as well as a loader equipped for the safe handling of tubular materials.

The power required for the drilling operations is provided by diesel engines, either through generators which supply electric motors or often by direct drive in the case of large equipments (drawwork, mud pumps, etc.).

Once the rig is assembled, the derrick raised, and the diverter welded on the conductor casing (to return the drilling mud to the tanks) the rig is ready to pick up a drilling bit and drilling pipes to spud the well.

Prior to mobilising and installing the drilling rig on site, it is customary to use a smaller, specialised drilling rig to pre-drill a conductor hole and two neighbouring small diameter holes. These two holes, known in the industry as the rathole and the mousehole, are respectively used during routine drilling operations to temporarily store the "kelly", a square or hexagonal pipe used to impart rotation to the drill string, and to store the next drill pipe to be added to the string.

Installing a surface conductor to a depth of approximately 12 m and drilling a rathole (~9 m) and a mousehole (~6 m) prior to the installation of the drilling rig, allow for drilling operations to begin immediately and to proceed more efficiently, as soon as the rig is set up.

Before drilling starts, the first phase consists in selecting and preparing a site to install the drilling rig and auxiliary services. Although the drilling rig itself only requires a level surface of some 60 m x 25 m, the need for adequate setback space between the well, the flare stack and the surrounding structures, including offices, lodging and laboratories, means that drilling companies must generally prepare an area of 100 m x 100 m. As well as maintaining safe distances between the different elements, an area this size allows for safe on-site handling and storage of the various equipment required for drilling operations.

The ground surface must also be prepared to make sure the ground will support not only the weight of the drilling rig, but also the weight of drill pipes or casings which can reach 180 tons.