Fundamentals of Drilling

Fundamentals of Finding, Drilling and Producing Oil & Gas

 Hydrocarbons - crude oil and natural gas - are found in certain layers of rock that are usually buried deep beneath the surface of the earth.  In order for a rock layer to qualify as a good source of hydrocarbons, it must meet several criteria.




Characteristics of Reservoir Rock

           For one thing, good reservoir rocks (a reservoir is a formation that contains hydrocarbons) have porosity. Porosity is a measure of the openings in a rock, openings in which petroleum can exist.  Even though a reservoir rock looks solid to the naked eye, a microscopic examination reveals the existence of tiny openings in the rock.  These openings are called pores.  Thus a rock with pores is said to be porous and is said to have porosity (Figure 1).

Figure 1: Porosity




           Another characteristic of reservoir rock is that it must be permeable.  That is, the pores of the rock must be connected together so that hydrocarbons can move from one pore to another (Figure 2).  Unless hydrocarbons can move and flow from pore to pore, the hydrocarbons remain locked in place and cannot flow into a well.  In addition to porosity and permeability reservoir rocks must also exist in a very special way.  To understand how, it is necessary to cross the time barrier and take an imaginary trip back into the very ancient past. special way. To understand how, it is necessary to cross the time barrier and take an imaginary trip back into the very ancient past.

Figure 2: Permeability



          Imagine standing on the shore of an ancient sea, millions of years ago.  A small distance from the shore, perhaps a dinosaur crashes through a jungle of leafy tree ferns, while in the air, flying reptiles dive and soar after giant dragonflies.  In contrast to the hustle and bustle on land and in the air, the surface of the sea appears very quiet.  Yet, the quiet surface condition is deceptive.  A look below the surface reveals that life and death occur constantly in the blue depths of the sea. Countless millions of tiny microscopic organisms eat, are eaten and die.  As they die, their small remains fall as a constant rain of organic matter that accumulates in enormous quantities on the sea floor.  There, the remains are mixed in with the ooze and sand that form the ocean bottom.

          As the countless millennia march inexorably by, layer upon layer of sediments build up. Those buried the deepest undergo a transition; they are transformed into rock.  Also, another transition occurs: changed by heat, by the tremendous weight and pressure of the overlying sediments, and by forces that even today are not fully understood, the organic material in the rock becomes petroleum.  But the story is not over.

           For, while petroleum was being formed, cataclysmic events were occurring elsewhere.  Great earthquakes opened huge cracks, or faults, in the earth’s crust. Layers of rock were folded upward and downward.  Molten rock thrust its way upward, displacing surrounding solid beds into a variety of shapes.  Vast blocks of earth were shoved upward, dropped downward or moved laterally.  Some formations were exposed to wind and water erosion and then once again buried. Gulfs and inlets were surrounded by land, and the resulting inland seas were left to evaporate in the relentless sun.  Earth’s very shape had been changed.

          Meanwhile, the newly born hydrocarbons lay cradled in their source rocks. But as the great weight of the overlying rocks and sediments pushed downward, the petroleum was forced out of its birthplace.  It began to migrate.  Seeping through cracks and fissures, oozing through minute connections between the rock grains, petroleum began a journey upward.  Indeed, some of it eventually reached the surface where it collected in large pools of tar, there to lie in wait for unsuspecting beasts to stumble into its sticky trap.  However, some petroleum did not reach the surface.  Instead, its upward migration was stopped by an impervious or impermeable layer of rock.  It lay trapped far beneath the surface.  It is this petroleum that today’s oilmen seek.

Types of Petroleum Traps

Geologists have classified petroleum traps into two basic types: Structural traps and Stratigraphic traps. Structural traps are traps that are formed because of a deformation in the rock layer that contains the hydrocarbons.  Two common examples of structural traps are fault traps and anticlines.






An Anticline trap is an  upward fold in the layers of rock, much like an arch in a building.  Petroleum migrates into the highest part of the fold, and its escape is prevented by an overlying bed of impermeable rock (A).












A Fault trap occurs when the formations on either side of the fault have been moved into a position that prevents further migration of petroleum.  For example, an impermeable formation on one side of the fault may have moved opposite the petroleum-bearing formation on the other side of the fault. Further migration of petroleum is prevented by the impermeable layer (B).








Stratigraphic traps are traps that result when the reservoir bed is sealed by other beds or by a change in porosity or permeability within the reservoir bed itself.  There are many different kinds of Stratigraphic traps. In one type, a tilted or inclined layer of petroleum-bearing rock is cutoff or truncated by an essentially horizontal, impermeable rock layer (C).



Or sometimes a petroleum-bearing formation pinches out; that is, the formation is gradually cut off by an overlying layer. Another Stratigraphic trap occurs when a porous and permeable reservoir bed is surrounded by impermeable rock. Still another type occurs when there is a change in porosity and permeability in the reservoir itself. The upper reaches of the reservoir may be impermeable and nonporous, while the lower part is permeable and porous and contains hydrocarbons.

Selecting a Drilling Location

          Coastal Petroleum Corporation Specializes in the Appalachian Basin for many reasons the number one reason is our success ratio of 100%.  The shallow wells we drill “1000 to 2200 ft.” are in the proven Upper Devonian Sands of Northwestern Pennsylvania.  The upper Devonian sands in Northwestern Pennsylvania are roughly 375 million years old and have produced abundantly since before the turn of the 19th century.  Colonel Drake discovered that oil can be produced from these sands in the first drilled well in the late 1800's near Titusville, PA.  Shortly thereafter, producers drilled and discovered oil near Warren in a number of formations.  The Bradford Third Field and the surrounding area produced nearly 700,000,000 barrels of oil and was once the largest oil field in the world!  Companies like Pennzoil, Quaker State, Dresser Industries, Birdwell, Forest Oil and many others all got their start here.  There are several potential pay zones that Costal Petroleum Corporation targets for hydrocarbon production in the Western Pennsylvania portion of the Appalachian Basin.  They include the Warren 1st, Warren 2nd, BallTown, Speechley, Bradford 1st, Bradford 2nd, Cherry Grove, Clarendon, Bradford 3rd, and the BallTown.  A typical Coastal Petroleum Corporation developmental oil well in Northwestern Pennsylvania is drilled to a Total Depth (TD) of 1,000 to 2,250 feet

 The deep wells “up to 10,000 ft.” we drill are Test wells or Wildcat wells that have a high success ratio and go through many different producing formations before reaching the Beekmentown Group of Hydrocarbons which is our target zone.  From the Utica Shale on down to the Rose Run Sandstone is where these wells become fun, if you hit anyone of these formations you can have a big well.  Once we know what we have as far as production we will then design the field around the test well.

Oil & Gas Producing Zones in Northwestern Pennsylvania


     Raising the Money to Drill

 Now that the area has been chosen and the location has been selected it is time to raise the money to drill, complete and get the new well ready to produce.  Coastal Petroleum Corporation offers several different programs throughout the year to fund their drilling projects. Our Programs are offered and sold to Investor  who qualify as “Accredited Investor ” as defined in Rule 501 of Regulation D promulgated under the Securities Act.


    Preparing the Location and Drilling the well

Drilling Vertical or Horizontal Oil & Gas Wells to Depth

  • There are two types of drilling rigs Coastal Petroleum. uses in our operations, for our shallow wells we will use a air rotary rig as seen in Figure 1.  And our deep well rig which uses both air and mud to drill to depth. Since the rig must go to 10,000 feet the rig is much bigger as seen in figure 2.


                    Figure 1                                                    Figure 2














         The final part of the hole is what Coastal Petroleum Corporation hopes will be the production hole. But before long, the formation of interest (the pay zone, the oil sand, or the formation that is supposed to contain hydrocarbons) is penetrated by the hole.  It is now time for a big decision.  The question is, "Does this well contain enough oil or gas to make it worthwhile to run the final production string of casing and complete the well?"


Examining Cuttings
















To help the Coastal Petroleum Corporation team make their decision, several techniques have been developed.  One thing that helps indicate whether hydrocarbons have been trapped is a thorough examination of the cuttings brought up by the bit.  The mud logger or geologist catches cuttings at the flow ditch and by using a microscope or ultraviolet light can see whether oil is in the cuttings. Or he may use a gas-detection instrument.

Well Logging    












         Another valuable technique is well logging.  A logging company is called to the well while the crew trips out all the drill string.  Using a portable laboratory, truck-mounted for land rigs, the well loggers lower devices called logging tools into the well on wireline.  The tools are lowered all the way to bottom and then reeled slowly back up.  As the tools come back up the hole, they are able to measure the properties of the formations they pass.   Electric logs measure and record natural and induced electricity in formations.  Some logs ping formations with sound and measure and record sound reactions.  Radioactivity logs measure and record the effects of natural and induced radiation in the formations.  These are only a few of many types of logs available.  Since all the logging tools make a record, which resembles a graph or an electrocardiogram (EKG), the records, or logs can be studied and interpreted by an experienced geologist or engineer to indicate not only the existence of oil or gas, but also how much may be there.  Computers have made the interpretation of logs much easier.

         After Coastal Petroleum Corporation carefully considers all the data obtained from the various tests, it has ordered to be run on the formation or formations of interest, a decision is made on whether to set production casing and complete the well or plug and abandon it.  If the decision is to abandon it, the hole is considered to be dry, that is, not capable of producing oil or gas in commercial quantities.  In other words, some oil or gas may be present but not in amounts great enough to justify the expense of completing the well.  Therefore, several cement plugs will be set in the well to seal it off more or less permanently.  However, sometimes wells that were plugged and abandoned as dry at one time in the past may be reopened and produced if the price of oil or gas has become more favorable.  The cost of plugging and abandoning a well may only be as low as $15,000 to a high of $25,000 dollars. Contrast that cost with the price of setting a production string of casing - $100,000 or more depending on the depth of the well.  Therefore Coastal Petroleum Corporation’s decision is not always easy.





    Stimulation of the Upper Devonian.  “Notching”









                        Shallow Well to 2200 Feet Deep

A typical stimulation technique used in the shallower (less than 2,200 ft) Upper Devonian reservoirs in the Bradford, Venango, Warren and Jefferson Counties in Pennsylvania, region is generally referred to as “openhole” or “packer and plugback” fracturing.  In this type of stimulation, the zone to be stimulated is uncased and “open.”  Multiple intervals are stimulated and “notched” with a downhole sandblasting technique.  A notch tool with small carbide nozzles is attached to the bottom of the tubing string and rotated as air and sand etch a ring or notch into the formation sand.  The notch usually has a 2-in. depth and acts much as a perforation in a cased well (as the initiation point for the treatment slurry).  The notches usually are treated separately and progressively down the well, a stage at a time.  The stages are isolated by use of a tension-set openhole packer and a pea-gravel filler referred to as “plugback.”  After notching, the well is filled with plugback to a point above the uppermost notch.  The packer is reverse circulated below the notch to be treated, then pulled above the notch and set.  This process allows many zones to be treated discretely.  These multiple fractures usually do not communicate during pumping, indicating that the fracture geometry is horizontal or highly inclined.  Although in use for years, this technique continues to be refined as additional production results are correlated to the number of stages.




Fracturing “Deep Wwells from 3000 to 10,000 feet”


          When sandstone rocks contain oil or gas in commercial quantities but the permeability is too low to permit good recovery, a process called fracturing may be used to increase permeability to a practical level.  Basically, to fracture a formation, a fracturing service company pumps a specially blended fluid down the well and into the formation under great pressure.  Pumping continues until the formation literally cracks open.  Meanwhile, sand, walnut hulls, or aluminum pellets are mixed into the fracturing fluid.  These materials are called proppants.  The proppant enters the fractures in the formation, and, when pumping is stopped and the pressure allowed to dissipate, the proppant remains in the fractures.  Since the fractures try to close back together after the pressure on the well is released, the proppant is needed to hold or prop the fractures open.  These propped-open fractures provide passages for oil or gas to flow into the well.







 Artificial Lift

After the well has been perforated, acidized or fractured, if the well produces by natural flow a Christmas tree will be installed, as pictured above. If the well doesn’t produce by natural flow in such cases, artificial-lift equipment is usually installed to supplement the formation pressure.

Sucker-Rod Pumps

          The artificial-lift method that involves surface pumps is known as rod pumping or beam pumping as pictured below.  Surface equipment used in this method imparts an up-and-down motion to a sucker-rod string that is attached to a piston or plunger pump submerged in the fluid of a well.  Most rod-pumping units have the same general operating principles.


Sale of Oil & Gas






           Once the oil is out of the ground and into the holding tanks, it must be sold.  These sale contracts are normally entered into for periods of not longer than a few months but in no case longer than one year.  The information will be compiled on division orders which are the basis upon which the buyer of the oil can divide the proceeds of sale. The buyer of the oil will pick up the oil from the holding tanks at periodic intervals, gauge it and remit the remaining proceeds in the proper amounts to the owners of the working interest and royalties. 
















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