There is no doubt that current oil prices are presenting a difficult challenge to the industry and stretching people’s creativity when thinking of solutions. Slashing costs, which means people and equipment, makes for more dramatic headlines, but simple efficiency gains also have their part to play as the industry adjusts to the new reality.

Extracting more from existing wells has an immediate effect on efficiency. A clear example is the migration of the shale operators to the most productive wells in the field that has seen production per well increase at the same time as the number of wells that are drilled dramatically decreases. Another way of increasing efficiency is to apply technological solutions that access more of the reservoir but from an existing wellbore or that provide more detailed well information that can optimize the amount of hydrocarbon extracted.

Two technologies that fit the bill are directional coiled tubing (CT) drilling and permanent monitoring with fiber-optic sensors. Both of these were in their formative phase in the early 1990s but have now developed into established products.

Directional CT drilling
The current sub $40/bbl oil market is putting a huge amount of pressure on operators to maximize the returns on current assets and to minimize the operational and financial risk associated with accessing these reserves. Reentering old wellbores and sidetracking to access new reserves in known reservoirs is a low-risk way to increase cash flow and return on investment from an operator’s assets (Figure 1).

Directional CT drilling (DCTD) is a well-established technology for doing this. Over the last three decades significant advances in equipment reliability, metallurgy and the experience levels of personnel has made DCTD a very attractive method of reentering wells. Operators and service companies can focus on delivering productive wells effectively rather than dealing with technology issues.

DCTD also can provide significant benefits that are applicable to drilling new wells or for reentry. One of the most significant advantages of DCTD is its suitability for underbalanced drilling, which allows the formation to produce oil and gas while drilling (Figure 2). That means the formation is not damaged like it is in overbalanced drilling. This reduction in formation damage can lead to significant increases in the amount of oil produced from each well drilled.

More complex operations such as multilateral branches, extension and larger hole sizes are being drilled, enabling operators to make the most of their existing reserves. Consequently, DCTD bottomhole assemblies (BHAs) are being deployed around the world to drill new wells and extend previous ones by accurately targeting pockets of oil and gas reserves. Successful drilling programs are ongoing in Saudi Arabia, Alaska and Australia as well as other places.

DCTD, MWD BHAs
Ten years ago AnTech combined mechanical, electronic and software engineers, and the COLT and POLARIS DCTD BHAs were created. The COLT MWD BHA is a 3.192-in. outer diameter (OD) BHA that is steered magnetically.

The POLARIS MWD/gyro-while-drilling BHA is a 5-in. OD BHA, which is steered either using magnetic sensors or a gyro. The BHAs are run on CT with seven-conductor electric line inside the tubing (also known as e-coil). The connection to the BHA from the surface via a cable allows real-time telemetry and very high data rates. This capability allows extremely accurate wellbore placement, thereby increasing the chance of success on a project.

The two BHAs are short—under 12.2 m (40 ft) in length—allowing them to be deployed above the BOPs. This means that the well can be closed in while the BHA is made up to the coil and pulled into the lubricator. The well is then only opened up once the complete pressure control envelope is in place.

Distributed sensing with fiber optics
Also in the early 1990s permanent well monitoring started to become more widely used (price of oil at the time was $20). The systems in those days were electrical and provided point measurements of usually pressure, temperature and flow.

In addition to the electrical systems that have become cheaper and more reliable now, a new generation of fiber-optic sensors is available to operators. The nature of fiber-optic sensor systems is that they can provide distributed measurements. If they are measuring a parameter such as temperature, the temperature can be recorded with a 1-m (3.3-ft) precision along the whole length of the cable. This provides a whole new dimension of visibility about the wellbore that was previously unavailable. Pressures and acoustic and seismic signatures can all be measured in this way.

When these fiber-optic cables reach the surface, they need to be terminated and connected to the surface instrumentation. Keeping optical losses to a minimum is vital to ensure that the resolution of the sensors is not affected.

As a result, a whole new range of equipment has had to be developed to adapt super-precision assembly to the rugged environment around the wellhead. This is also a hazardous-area environment where electrical equipment needs to conform to international standards for use where explosive gases are present, such as the International Electrotechnical Commission System for Certification to Standards Relating to Equipment for Use in Explosive Atmospheres.

AnTech’s dedicated products division has developed a whole new range of fiber-optic products, which continues to grow. Demands for equipment that can safely allow fiber-optic connections to downhole gauges in HP/HT environments can now be met.

AnTech has recently launched the Type-F range of fiber-optic wellhead outlets, which incorporates proprietary feedthrough that is designed to American Petroleum Institute 6A standards.

Furthermore, design and development on an explosive atmosphere certified Fusion Splicer has begun, and this will in turn help complement the Type-F wellhead outlet range by safely splicing delicate fiber at the well site.

Change can be a challenge in an industry that is historically cautious about change, and this is for a good reason. The risks of failure with new technology are high, so the benefits need to be significant. DCTD and fiber-optic monitoring are two technologies that have shown their worth over time, and now might be the time when these innovations offer an economic solution in a turbulent and challenging market.

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