What Questions To Ask Before Buying A Drilling Rig

Top Factors and Absolute Guide for Rotary Drilling

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There are various methods and techniques for rotary drilling, every method has its own significance depending on sub-surface conditions. Drill cuttings require continuous removal which separates each drilling technique. In this blog, we will talk about the following:-

  • What is Rotary Drilling?
  • History and Current Technologies of Rotary Drilling.
  • General Rotary Drilling Methods.
  • Types of equipment and Rotary Drilling components.
  • Advantages of Rotary Drilling Rig.

What is Rotary Drilling:

Rotary Drilling refers to the use of sharp, rotating drill bit to cut or crush by applying downward pressure. It is mostly used to drill big holes in pit mines, petroleum extraction and other various fields. To gather information about coal deposits drilling is the most trusted and reliable method. Before drilling, coal prospecting is done to discover coal resources through search.

  • Rotary drilling is a general method in drilling in which a string of drill pipe is hung from a derrick and turned by the engine.
  • Rotary cutting is also used to drill small boreholes in soft rocks.
  • For medium to hard rocks, rotary crushing is used.
  • Ai rotary drilling is used to drill deep boreholes in rock formations.
  • One of the crucial factors with the drilling program is to do selection between core drilling and rotary drilling.
Top factors and Absolute Guide for Rotary Drilling

Current Technologies and Innovations:

  • New technologies have reduced the environmental impact of energy production by allowing more oil and gas.
  • Discovery of new resources plays a crucial role in meeting global energy demand.
  • Technological Advancements are used for well drilling and completion have enabled energy industry to reach new sources of oil and natural gas.
  • Companies can push length in excess of 3,000 meters as compared to 30 meters a few decades back.
  • Horizontal drilling is a directional drilling process which provides more contact to reservoir formation than a vertical well and allows an increase in the production of hydrocarbons.
  • When oil and natural gas are in separated layers, multilateral drilling allows to branch out from main well to tap reserves.
  • When vertical well cannot be drilled, Extended reach drilling allows producers to reach deposits that are great distances away from a drilling rig.

General Rotary Drilling Methods:

Drilling method varies from digging with tools to high-speed drilling with types of equipment. Small to medium-sized drilling rigs are mobile, such as those used in mineral exploration drilling, blast-hole, water wells. Larger rigs can drill thousands of meters of Earth crust, using large “mud-pumps” to circulate drilling mud through the drill bit.

Air Rotary:

  • To drill deep boreholes in rock formations, air drilling is used.
  • Circulating air is used in this method to cool drill bits.
  • By rapid rotation of drill bit, borehole advancement is achieved.
  • Several variations in air rotary techniques includes air rotary casing hammer(ARCH), down hole hammer and under reaming.
  • In ARCH, often called “top drive”, both rotational downforce and impact force are provided by an above-hole impact hammer and a rotating drill head.
  • Under reaming is a variation of the top drive casing advancer method that uses a rotating cutting bit in front of the advancing casing.

Mud Rotary:

  • Drill bit cuts the formation into small pieces, called cuttings.
  • These cuttings are removed by pumping drilling fluid through drill pipe called mud.
  • The drilling fluid is also used to cool the drill bit and stabilize the borehole wall, prevent fluid loss into the formation.
  • Mud rotary is often used in soft sediments that may or may not be saturated with groundwater.

Dual Rotary:

  • Unlike other drill rigs which use only an upper drive, dual rotary uses both an upper and a lower head drive to advance the drill bit and casing.
  • Dual rotary technology delivers powerful performance in unconsolidated overburden (sand, gravel, cobbles, and boulders) where other technologies struggle to drill a cased hole.
  • A top drive rotary head simultaneously handles a drill string equipped with either a down hole hammer, drag bit or rolling cone bit to drill the centre.

Reverse Circulation:

  • In reverse circulation, rotational and impact energy are delivered in the same manner as direct air rotary.
  • Samples are obtained when high pressure compressed air is injected down the annular space.
  • Samples of the substrate from the reverse circulation method are often thought to be more correlative to the depth of the bit face and are favoured in mineral exploration.

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Basic Rig Components

Components of Rotary Drilling System:

Actual mechanics of modern rigs are quite complicated while concept of rotary drilling-using a sharp, spinning drill bit to delve into rock is quite simple.

Basic Rotary Drilling system consists of 4 groups of components:-

Prime Movers

  • Prime movers are also known as power system of a rotary drilling rig as they provide power to the entire rig.
  • When drill rigs were started, steam engines were used to provide power. Use of diesel and gas engines was common post World War II.
  • Natural gas is also commonly used to generate electricity and power rig on site.

Hoisting Equipment:

  • Hoisting Equipment is made up of tools which are used to raise and lower when equipment go into or come out of the well.
  • To support cables and pulleys, derrick is used which is also known as the most visible part of hoisting equipment.
  • In deep wells, the combined weight of the drill pipe, drill bit and drill collars may be more than over thousands of pounds.

Rotating Equipment:

  • Rotating Equipment is responsible for transferring power from the prime mover to drill bit.
  • Swivel a freely rotating equipment carries the entire weight of drill string which is attached to hoisting equipment.
  • Below the drill pipe is the drill collars which can be altered depending on down-hole condition experienced while drilling.

Circulating System:

  • Three important objectives of the circulating system are cooling and lubricating the drill bit, removing debris and cuttings and coating the walls of well with mud type cake.
  • Drilling fluid is circulated down through well hole throughout the drilling process.
  • Circulating system consists of drilling fluid pumps, compressors, speciality injectors and plumbing fixtures.

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Advantages of Rotary Drilling Rig:

  • Lightweight modular design allows greater operational flexibility and makes the rigs easy to install and relocate.
  • Drilling rigs are hydraulic with self- propelled and also equipped with computer operating systems.
  • According to strata drilling, bits are configured, working in clay soil requires long drilling tube while short drilling tube is suitable for strata containing sand and cobble.
  • Better penetration rate and high operational efficiency is achieved by the use of drilling muds which controls downhole pressure, stabilize the hole well, remove drill cuttings and lubricates the drilling bit.
  • Rotary drilling rig is considered eco-friendly because of smaller vibrations and less-operating noise.

Major Dewatering Techniques

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Dewatering means controlling groundwater with the simplest form of sump pumping by collecting groundwater in a sump and pumped by solids handling pumps. Every project brings unique conditions so it requires the right dewatering process.

Dewatering of excavations is required at construction sites generally for foundation works. Various methods for dewatering of excavations are described in this article. Firm and sound working conditions are indispensable when the construction of buildings, powerhouse, dams, and other structures has to be executed. These structures not only require a dry base for their foundations but also good water-table stability in the girth.

The different methods available for dewatering of excavations at constructions sites are not necessarily interchangeable as each one has a narrow range of applications, therefore, adopting the right method of dewatering for a particular ground condition is always a critical and a difficult decision to make.

Dewatering of an excavated area is done to keep the excavation bottom dry, to prevent the leakage of water or sand and to avoid upheaval failure. Dewatering could turn out to be a herculean task if one doesn’t adopt the right method.

Principal Dewatering Techniques:

While choosing a dewatering technique impact on groundwater should be kept in mind. The use of the right technique is important in every construction project. There are four principal dewatering pumping techniques. These techniques are not readily interchangeable. Each technique has a relatively narrow range of application relative to two key parameters: the drawdown required and soil permeability.

The main dewatering techniques are:

  • Wellpoints
  • Sump Pumping
  • Educator Wells
  • Deep Wells

Wellpoints Dewatering Technique:

The wellpointing method uses lines or rings of closely spaced shallow wells (wellpoints) installed around the excavation. The wellpoints are connected to a headerpipe and pumped by wellpoint pumps which can handle both air and water. The system operates on the suction principle, so drawdown by this method is limited to 5 or 6 m below the level of the wellpoint pump. If deeper drawdown is required than wellpoints may have to be installed in multiple stages.

Sump Pumping Dewatering Technique:

The sump pumping method allows the groundwater to seep into the excavation, where it is collected in sumps (special pits within the working area) and pumped away by robust solids-handling pumps. This method is applicable to relatively shallow excavations.

Deepwells Dewatering Technique:

The deepwell method uses bored well pumped by electric submersible pumps to lower the groundwater level below the excavation. Wells are normally installed at relatively wide centres around the outside perimeter of the excavation. Wells are sometimes installed within the excavation itself. The method is well suited to relatively deep excavations where large drawdowns are required.

Eductor Wells Dewatering Technique:

The eductor well method (also known as ejector wells) is a specialist dewatering method used to control pore water pressures in low permeability materials such as silts or fissured clays. The method operates on the venturi principle, whereby circulation of high-pressure water through eductors in the base of each well creates a vacuum which promotes drainage of low permeability strata.

Every project brings with it a unique set of challenges and opportunities. With around 5 decades of experience in the industry, PRD Rigs supplies a wide variety of equipment that caters to any requirement the project may have.

In addition to the primary methods described above, there is another segment in the industry where dewatering is required in waste disposal. This is otherwise known as sludge dewatering

Sludge Dewatering Methods:

In these methods, sludge is separated into solid and liquid for proper waste minimization. Dewatering requirements need to be evaluated by designers for planned sludge disposal. Dewatering only separates solid and liquid components not treat sludge or liquid. After separation contaminates can be treated separately in liquid and solid.
There are various technologies for sludge dewatering, including plate & frame and belt filter presses, centrifuging, and geomembranes. In addition to these, there are other options available.

Different types of Sludge:

  • Primary Sludge

    • It comes from the settling process and made of easily decantable suspended particle. Volatile Solid content is between 55%-60% with excellent dewatering ability.
  • Biological Sludge

    • It comes from the biological treatment of wastewater and made of a mixture of microorganisms, mainly bacteria. A simple decantation in the clarifier will easily separate the bacterial flocs from treated water.
  • Mixed Sludge

    • Mixed sludge is made of primary and biological sludge. Blending ratio of primary sludge is 35%-45% and for biological sludge is 55%-65%.
  • Digested Sludge

    • Stabilization is done on biological or mixed sludge under different temperatures to produce digested sludge. A dry solids content around 20 g/l to 40 g/l.
  • Physico-chemical sludge

    • Physico-chemical sludge comes out after physicochemical treatment of wastewater. Feature of sludge is the pollutants in water and chemicals used.
  • Mineral Sludge

    • Because of mining beneficiation process or quarries, this name is given. Nature is essentially mineral particles of various sizes.

Parameters which effects Dewatering of Sludge:

  • Concentration (g/l)
  • Organic matter content
  • Colloidal nature of sludge

Why Dewatering is Necessary:

  • Waste Minimization
  • Cost Efficiency
  • Sustainability Objectives

Industrial Watering Methods:

Plate and Frame Filter press

Recessed chamber plates are used for the separation of solids and liquids.
A chamber is formed by joining two plates to pressurize the slurry and squeeze the filtered out.
Filter cake is collected on plates and dropped on the conveyor.
These are highly effective and produce filter cake that is between 40% and 70% solids by weight.
Biological sludge.
API separator sludge.
Cake like solids are produced which are cost-effective in transportation.


It is a device used to separate materials based on densities.
Buoyancy is the basis for a centrifuge.
Low-density components will be suspended above and high density will fall at the bottom.
25% to 35% solids by weight is produced.
Beneficial in heavy sludge oil watering and municipal wastewater treatment.
Centrifuges typically produce between 25% and 35% solids by weight.
Advantage of Centrifuge is the speed of the process.

Belt Filter Pass:

Highly applicable in high moisture content.
Produces 18% to 25% solids by weight.
Effective on high-volume waste streams where a large production of low-quality filter cake is acceptable
Belt press is useful in paper mill sludge, river silt, municipal wastewater treatment sludges.

How to select the right method:

Dewatering is used in cities for wastewater treatment plant, drinking water facility, refinery. Project necessitates and knowing different materials helps in determining need. Contact us to learn more!

Vacuum Dewatering Techniques

Vacuum Pressure is applied to remove water from vacuum concrete after placing concrete structural members. This process improves strength, durability and other properties of concrete. The technique is generally used on horizontal surfaces.

When the vacuum is being applied for 3 to 5 minutes of water content of concrete gets reduced by 20 to 25 percent. For the chemical reaction of cement and water, the ratio of water-cement should be less than 0.38. For proper placing in framework, workability is also a crucial factor. After workability excess water will be evaporated leaving behind capillary pores. The effectiveness of the process reduces with time and is generally only applied for up to 30 minutes. Vacuum dewatered concrete stiffens rapidly. Where a smoother surface is specified, power troweling is done, usually 30 to 90 minutes after the planing operation.

4 Components Required in Vacuum Dewatering of concrete:

  • Vacuum Pump
  • Water Separator
  • Filtering Pad
  • Screed Board Vibrator


Vacuum extracts water and store in water separator.
Mats prevent the removal of cement with water.
The Magnitude of water will be equal to a contraction in the volume of concrete.
Reduction will be up to 3%.

Disadvantages of Vacuum Dewatered Technique:

Seepage of oil and water weakens the concrete.
High Initial Cost.
Requirement of trained Labor.
The best-laid floor (Trimix) can have undulations of above 5mm (not normally visible to the naked eye).

What Questions To Ask Before Buying A Drilling Rig?

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Purchasing a drilling rig has never been an easy task to do as it requires a huge amount of investment. Purchasing a perfect rig can just make or break the deal. There are many reasons to buy a rig. It may be for an established business that might want to upgrade its fleet with new technology or might be a newcomer who wants to open a business and wants to purchase a rig for the first time. Any of the above instances require different rigs, which have a different selection process including particular requirements, horsepower required, which technology is needed etc. We at PRD Rigs are here to solve your problem.

What Questions To Ask Before Buying A Drilling Rig

Buyers always get confused between purchasing a new or a used rig. Buyer has a perception that by purchasing a used rig will save them money. Purchasing a new drilling rig just makes the deal as it can fulfil all the requirements needed and all the parts are in new condition, but when looking for a used rig, Owner may have used the rig aggressively which may not be seen in the advertising. A used rig will cost the same as a new rig as it requires some additional work after purchasing. Also, an overlooked factor in buying a used rig why is the owner selling it? This may affect the price. It may be that he is retiring or that he has changed his business or has completed his work with that particular project. The fact is that it’ll cost the same either by purchasing a used one or by purchasing a new one.

Other questions to be asked before buying a drilling rig are:

What is the purpose of the drilling?

Before purchasing a drilling rig, you should be very specific with the proposed for the drilling. For example, water well drilling requires different system and soil sampling different.

Where do you want to drill?

This plays a vital role in selecting the power of your rig. There’s a lot of difference between drilling on a plain surface and drilling in mountains. Drilling in the mountains requires more horsepower which increases fuel consumption.
We at PRD Rigs have all types of rigs that will just make your deal.

What is maintenance costing?

Before buying a rig you should also see the maintenance cost that depends on the model you select. Also, see the operating cost depending upon the power of the rig and fuel consumption.
At PRD Rigs you’ll get low maintenance rigs.

What is your target budget?

Size, capabilities and shipping considerations all need to be taken into account when thinking about how much your business is able to commit and here at PRD Rigs we help you in giving the best products at the best prices.

water well and supplies

Things to Consider for Dewatering

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Before we jump into the factors that are considered for dewatering, we have to understand what exactly Dewatering means.


Dewatering is the process of draining an excavated area that is flooded with rainwater or groundwater before construction to lower the water level so that construction can start. This process is usually applied when there is an accumulation of groundwater at a construction site where Sewer lines have to be laid or evacuation for Bridges foundations and basement has to be carried out.
Now there are different types of Dewatering for different sites of constructions using different methods.

Things Consider for Dewatering are:

1. Understanding the type of land

This is the first step in this process because different land have different soil properties, so it is important to study like what type of ground are we work on or what type of soil is this and then make a proper plan about how things are done

2. Check signs of soil erosion or the instability

Instability or Erosion is one of the biggest problems in large construction projects. Controlling erosion is important not just for preserving the construction site and protecting the new structure but also protecting the workers, laborers, machinery, and environment

3. Choosing the right Technique or Method

Choosing the right method. Since there are different types of Dewatering for Different types of Constructions, it becomes very important to select a suitable method for the respective Site. PRD Rigs provide Effective drilling solutions. We are backed by an extensive service network in 10 locations over the globe.

4. Understanding the weather conditions

It is very important to consider weather conditions when you are performing excavation process You should avoid dewatering under heavy rains because the infiltration rate is at a minimum and water will move slower or just the dewatering process will not function.

5. Choosing the right dewatering pump

Applications for dewatering pumps vary from clearing floodwater or draining reservoirs to sewage bypass or groundwater dewatering. So, when building a pump portfolio, it’s essential to choose equipment that is versatile, productive, safe and trouble-free. PRD Rigs is a leading global player in providing the best drilling and dewatering equipment.

6. Understand the water table conditions of the ground

It is important to understand the water table conditions in the area, perhaps the underground water is always near the surface, so your plan might not work, therefore it is better to make a better plan according to the water table

7. Discharge of Water

Never discharge water that has been contaminated with oil, grease, or chemical products directly this can cause serious injury to the workers. In such instances, an oil/water separator may be necessary.

8. Sump pumps

Sump pumps are the most common dewatering technique but can handle only a small volume of water use different techniques for large amounts of water.

9. Using Dewatering Bags

Dewatering bags are made of Synthetic Fiber (Geotextile Fiber) that filter the water by removing sediments and rocks from the water they’re placed on high water table area that is near to the shoreline

10. Check for Permission or Permit

Check if additional permits and requirements might be needed from the state or local government agencies for a smoothly working environment without any hindrance

Methods of Dewatering

4 important types of Dewatering Methods are as follows:

  • Open sump pumping method
  • Deep wellpoint method
  • Wellpoint method of Dewatering method
  • Eductor Wells method

Some other major techniques are

  • Artificial Recharge
  • Relief Wells
  • Siphon Drains

We at PRD Rigs provide the worlds best drilling solutions with best-in-class products using sustainable energy and future technology, delivering economic and user-friendly safe drilling.
We house two state-of-the-art manufacturing facilities and we are backed by an extensive service network. Our company employs more than 500 trained employees and our manufacturing units totally span 55,000 sq.meters, with a plan for expanding more.
If you have any queries regarding our services feel free to contact us.

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Choosing The Right Drilling Rig – Do’s and Don’ts

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Many jobs require drilling. There comes a time in every driller’s life when a new rig has to be bought. If you are in the market for one and are looking for information that can help with making the right purchasing decision then you have landed at the right place. Read on to determine some of the essentials when it comes to choosing the right rig for your objectives.

A few types of drilling example:

  • Pile Drilling: To support a building on unstable ground
  • Micropile Drilling: To reinforce existing structures
  • Drilling Wells and Oil Rig: To access groundwater or oil
  • Geothermal Drilling: To access and extract the Earth’s heat
  • Blast Hole Drilling: For quarries
  • Continuous Flight Augering: Maintains the walls of the borehole with the drill cuttings that are driven by the auger.

Let us start with the basics. So, what is a Drilling Rig? – It is a type of construction equipment used to make holes in the earth’s surface. There are many variations of drilling rigs that vary considerably in size: they can be massive structures or light enough ones which can be moved manually by a single person.
Drilling rigs can take samples from mineral deposits and are capable of testing the physical properties of rocks, soil and groundwater as well. Additionally, they can also be used for underground installations: tunnels, shafts or pipes. Having said that, choosing the right rig doesn’t really have to be a daunting task. You just have to make sure exactly what you intend to use it for and what kind of terrain it will be used on.

The Do’s:

  • Always make sure to choose the rig according to the terrain you are going to be working on.
  • Inspect the rig thoroughly before purchase. Check to ensure it meets with all the quality standards and has sufficient drilling fluid to avoid any accidents or mishaps
  • Proper maintenance is the key to the long life of your rig. Do make sure to maintain it on a regular basis to avoid any breakdowns
    Safety, reliability and ease of use are also important elements to consider before purchase
  • Make sure the drilling contractor you are dealing with promises the rig to be delivered on time without any delays and has great after-sales service. This is vital in case of any breakdowns
  • Be wary of the speed & power of the drilling rig. This can help save a lot of time for your workers during the drilling process and increase efficiency
  • Ascertain the drilling contractor you are about to place the drilling rig order with has a global presence and has happy client testimonials. This gives off a sense of credibility and trust in the market

The Don’ts:

  • Improper Maintenance – Failing to maintain a drilling rig can cause serious damage to the equipment. It could also cause the drill rod to stop functioning which may cause injury or death to the rig operator. Other factors include, leaks in the hydraulic or fluid pump systems can cause shortages or cause the machinery to seize up while working and cause costly project delays
  • Do not be hasty in your decision and succumb to high pressure. Always take the time out to research and see which contractor offers the best solution to your business needs
  • Do not purchase a used drilling rig. No matter how tempting it may be due to factors such as low price, short delivery time, local contractors, etc, as it may not be future proof and there will be a high chance of a breakdown
  • Drilling Industries are sanctioned to have their own auxiliaries such as drilling bit, drilling pipe, drill string, etc to help support the drilling process adding further enhancements. But the quality of these supporting equipments may not always be up to the mark.
  • Therefore, it is imperative that a thorough inspection of these products be done before hand, if you are planning to buy it from your contractor itself
  • No proper research – Factors such as size, capabilities and shipping considerations all need to be taken into account when thinking about how much your business or organization is able to commit to

Did you know?

There are two main types of drilling rigs: autonomous crawlers and truck or trailer-mounted.
Crawlers are used when you need to move at a low speed over unlevel areas or on very loose grounds. The truck or trailer-mounter drilling rigs are comparatively cheaper than crawler drilling rigs but they are not free in terms of movement or their energy source which may come from the transport truck or an independent generator.

Bonus Tips

To avoid any injury at the workplace, be sure that the workers are geared with proper protection equipments before the commencement of any drilling operations.
When it comes to the oil and gas industries, the biggest concern surrounding this will involve fire, particularly oil companies. There will never be a shortage of flammable substances on-site at an oil rig, with explosions and spreading fires being a common threat. If you are familiar with the Piper Alpha disaster of 1988 then you would be aware that it’s essential that all pipes and installations throughout the rig are entirely secure and sound for the oil workers.

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