Selection of Drilling Rig

Water is the single most important substance for sustaining life. As World population grows the need for new resources of water to meet growing demands also increases, because groundwater is one of the 'major source of the supply man through the years has devised various methods to tap this hidden treasure. Because of varying conditions and varying needs it is often difficult to choose the best equipment to do the job. Today 97% of the world supply of the fresh water is through groundwater and wide variety of modern water well drilling equipments are available to probe for and reach groundwater supplies.

Water well drilling is both an art and a way of life" for those engaged in this occupation. To old time drillers nothing else can take the place of "putting down a hole". New comers today needs this field will find, too that well drilling is stimulating and rewarding occupation.

Before preparing drilling programme it is essential to have the water well rigs which needs your specific drilling requirements.

A rig that performs your job demands) as well as) the economical operations necessitates for maximum profitability in minimum time. Therefore, whenever you are inclined for buying a new rig whether, rotary, down the hole or a percussion, check out the following features before selecting the rig which can save you a real money and the term right rig for right formation can be implemented sincerely with minimum investment. 

If you are going to drill a hole in a hard, abrasive, alluvial soil, clay mixed with kankar and sandstone, gravel etc. etc., then opt for a mud rotary drilling rig. The size and depth of the borehole is pre-requisite before selection of the rig.  Once the size and depth of the bore hole is known, following features of the rig may be evaluated carefully;

Design and capacity of the mast.

Size and type of rotary table.

Capacity of draw-works.

Capacity of mud pump pressure, volume etc.

Capacity of prime-mover, H.P., RPN, Torque etc. etc

Drive and capacity of compound case.

Whether trailor mounted or truck mounted.

Capacity of hydraulic pumps for lifting mast.

Pull down and pull back forces if the rig is fitted with pull down system.

Select the size of drill pipe in accordance with the mast capacity, depth and size    of hole.

Accessories as per requirement.

If, you are drilling in a hard rock formation like granite, gneisses, decan trap, besalt, schist etc.etc. and size and depth of hole is known, opt for down the hole hammer rig and the following features of the rig may be evaluated carefully;

Design and capacity of the mast.

Torque and speed requirement of top head drive.

Pull down and pull back forces. Feed system.

Type and capacity of Compressor pressure, volume etc.

Capacity of prime mover, H.P., RPM etc.

Capacity of mud pump pressure, volume etc.

Capacity of water injection pump,  pressure, volume etc.

Drill pipe size and storage capacity.

Casing handling capacity.

Jib boom and winch capacity.

Safety shut down system. Cooling  system of the rig.

Lubrication system.

Electrical system.

Whether truck mounting or trailor  mounting.

Accessories as per requirement of  the  rig.

Casing driver / odex, if required.

If you are going to drill a hole in semi-consolidated hard and bouldery formations and size and depth of hole is known, opt for percussion rig and the following features of the rig may be evaluated carefully:

Design and capacity of the mast.

Maximum tool weight.

Construction of spudding beam with stroke length.

Bull reel capacity and size.

Casing reel capacity and size.

Sand reel capacity and size.

Design of jack shaft.

Whether tailor mounting or  truck mounting.

Capacity of prime-mover H.P., RPM.etc.

Type of transmission.

Type and size of clutches and brakes.

Type of sheaves and bearings.

Type and size of leveling jacks.

Accessories as per capacity of  the rig.

Since, the huge initial capital investment is involved once the type of formation characteristic, size and depth of bore hole to be drilled is known, you can always opt for the right rig to mitigate the requirement of your drilling programme.

For example, there is no fun in buying a heavy duty rig just for the construction of 4"-6" shallow test wells. This can

be drilled by a lighter capacity of rig with a suitable size of drill pipe and accessories, at much lesser cost. 

Selection of the best drilling method for an exploratory drilling required an understanding of the geological conditions and the physical limitation of drilling rig and equipment. Many of the drilling problems regarding the operation of drilling equipment as well as the problems of sub-surface condition has been in past and will be there in the future. The services of a skilled and experienced drilling engineer is most required thing who diagnose the troubles and keep the rig operative in a most efficient.

Manner with a minimum down time. To drill a well in a most economic and efficient manner it is always essential to maintain the proper drilling records and the samples as the drilling progresses. No doubt, the performance of drilling rigs reduces considerably with the passage of time in terms of rated capacity etc. Yet, it can construct a successful well of lesser depths and size irrespective of the age of drilling rig and accessories.

Considering the capital cost involvement, rate of drilling per meter and rate of penetration in various geological formations one can always select a most economical and efficient drilling to full fill the requirement as per table given below :

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