Saturday, March 22, 2014

Onshore Drilling (Part 2)

Cable tool drilling has historically taken many forms. These tools have now become so sophisticated, and so complex, that it takes a company like Laversab oilfield systems to generate said tools. Laversab oilfield systems has created highly advanced surface system equipment. In the early days of percussion drilling, equipment was very crude compared to today’s technology. The ‘springpole’ technique, used in the early 1800s, consisted of a flexible pole (usually a tree trunk) anchored at one end, and laying across a fulcrum, much like a diving board. The flexible pole, or springpole, would have a heavy bit attached at the loose end. In order to get the bit to strike the ground, workers would use their own body weight to bend the pole toward the ground, allowing the bit to strike rock. The tension in the pole would spring the bit free, in case it became stuck in the ground.

Many improvements have been made since these early percussion rigs. In fact, it was from cable tool drilling that one of the most important drilling advancements was made. In 1806, David and Joseph Ruffner were using the springpole technique to drill a well in West Virginia. In order to prevent their well from collapsing, they used hollow tree trunks to reinforce the sides of the well, and to keep water and mud from entering the well as they dug. They are credited as the first drillers to use a casing in their well – an advancement that made drilling much more efficient and easily accomplished. It is believed by many that ‘Colonel’ Drake’s 1856 well achieved success due to the use of steel casing to reinforce the well. Drake’s well was drilled using steam powered cable tool drilling methods.

Innovations, such as the use of steam power in cable tool drilling, greatly increased the efficiency and range of percussion drilling. Conventional man-powered cable tool rigs were generally used to drill wells 200 feet or less, while steam powered cable tool rigs, consisting of the familiar derrick design, had an average drilling depth of 400 to 500 feet. The deepest known well dug with cable tool drilling was completed in 1953, when the New York Natural Gas Corporation drilled a well to a depth of 11,145 feet. Despite the historical significance of cable tool drilling, modern drilling activity has shifted mainly toward rotary drilling methods. However, the foundation of knowledge laid by years of cable tool drilling is, in many cases, directly transferable to the practice of rotary drilling.

Horizontal Drilling

Horizontal drilling is flexible in that it allows for the extraction of natural gas that had previously not been feasible. Although on the surface it resembles a vertical well, beneath the surface, the well inclines so that it runs parallel to the natural gas formation. These legs can go in different directions at different depths and can be more than one mile long horizontally, in addition to the vertical well that can be thousands of feet below the surface. Horizontal drilling allows one surface well to branch out underground and tap many different natural gas resources. It also allows the well to make contact with larger areas within productive formations.