DRILLING/WELL COMPLETION

What is the future of multilateral technology?

Advances in multilateral drilling and completion technology promise reduced costs, greater flexibility and increased profit potential

Jim Oberkircher, Halliburton Energy Services, Sperry-Sun Multilateral Systems, Houston

n the last 10 years, thousands of multilateral wells have been drilled worldwide. Still, only a small percentage of the total number of wells drilled is multilateral. Lack of concise information and misconceptions surrounding the costs and perceived risks have conspired to hinder large-scale implementation.

However, recent advances in the capabilities of the systems and applications have proved multilateral drilling and completion to be a truly revolutionary and cost-effective solution for the industry. What makes this revolutionary? Simply put, multilateral technology (MLT) provides options that help mitigate adverse economic climates and operating conditions, Fig.1.

Fig 1. Different TAML levels offer different capabilities using multilateral technology.

Stiff decline rates have compelled key industry decision-makers to renew their reservoir management efforts to increase the productivity of fields and wells during their entire economic lives. As usual, necessity is the mother of invention, and this environment has produced thousands of openhole (TAML – Technical Advancement for Multilateral; Level 1) multilateral wells in, for example, the Austin Chalk and various carbonate and hard-rock formations around the world. In addition, many TAML Level 3 – 4 wells have been drilled to recover heavy oil deposits, with the vast majority being in Canada and Venezuela. These examples reflect a major breakthrough in enhancing profitability from difficult reservoir or fluid types, and are largely adaptations of existing oilfield technology and drilling techniques to enhance the reservoir’s ability to produce, Fig. 2. Consistent operational success of these applications has significantly minimized the perception of risk.

Fig 2. Multilateral well designs have greatly enhanced the profitability of heavy oil developments.

However, this technology has not been confined to land or heavy-oil wells; in fact, MLT has been implemented in many marine areas, including the hostile environment of the North Sea. The recent implementation of MLT has added millions of barrels of recoverable reserves to a North Sea field, enhancing the value of the entire project. This was brought about by the use of a TAML Level 5 system, which allows for pressure segregation at the junction.

MLT Reduces Costs

One economic benefit of MLT is enhancing reservoir flow characteristics, but reducing well construction costs is also a strong incentive for using MLT. A multilateral well can be drilled for 1.2 – 1.8 times the cost of a single conventional well. Obviously, the benefits of adding incremental reserves and production rates for some fraction of the cost of a conventional well can dramatically affect economics. This can also enable access to previously uneconomic reserves. This impact depends on the incremental reserve’s value and the original typical well cost. It is more dramatic in areas that have a large capital cost associated with them, such as deep or extended-reach wells. But the economies of scale also prevail in areas traditionally thought to be outside the realm of MLT implementation. Areas that have relatively low capital well costs have very robust economics when multilateral wells are drilled vs. conventional wells.

Promising Prospects For MLT Applications

MLT has steadily progressed with increased systems capabilities and greater familiarity and experience with the applications. More than a vague notion, MLT should be a viable alternative to traditional field development.

Many MLT applications remain to be vigorously pursued, such as in exploration wells, mitigating geologic risks and navigating non-heterogeneous reservoirs. Laterals could easily delineate exploration targets, while maintaining access to the main bore. They can also minimize the impact of geologic uncertainty by facilitating the ability to re-drill to other positions if the original target is not achieved. And, they can reduce the effects of smaller-than-expected reservoir drainage patterns by putting in more "straws," effectively draining otherwise bypassed reserves. In these cases a "shotgun" approach of cost-effectively multiplying the potential reservoir penetrations can reduce geologic and reservoir risk.

Gas wells constitute a small minority of multilateral wells drilled, so MLT has yet to exploit gas exploration and production. MLT may significantly impact reservoir spacing in deep, tight gas wells by helping achieve optimal reservoir drainage spacing now impeded by the economics of drilling to deep reservoirs.

Still to be realized is the truly dramatic effect of developing a field from inception using MLT. Consider the savings potential of reducing the number of wells drilled from almost any facility. From deep water to land, reducing topside cost significantly affects the overall economics of a field development. This is compounded when you consider that facility costs are up-front capital investments that have a delayed return until first production is achieved.

Facility size is also a consideration when drilling in environmentally sensitive areas. But to realize this benefit, multilateral wells must be part of the initial planning process during the project design phase. Otherwise, MLT falls short of its fullest potential. Because MLT applications involve many aspects of drilling and production, a total integrated approach should be used during job design and installation. Compatibility issues require a complete analysis of each segment of the reservoir development plan, drilling / completion program and facility design, to optimize technology interfaces at each step.

The future grows brighter for MLT because of its synergistic influence on other emerging technologies. The amalgamation of emerging technologies (intelligent completions, expandable tubulars, advanced drilling and production systems, real-time information flow, downhole factory, etc.) through MLT demonstrates the quantum leap of this technology from discrete MLT hardware to a production system – a leap that will address maximized reservoir understanding, production and control. This will constitute a total production system that will have a revolutionary impact on the energy industry.

Compelling economic factors now make MLT solutions more acceptable to operators. Today, with rapidly increasing recognition of effective multilateral solutions, it is evident that suppliers and designers are being asked to break new ground continually. Recent advances in multilateral drilling and completion technology address all of the crucial economic issues in a very positive way, and promise greater flexibility and profit potential for oil and gas companies producing on land and offshore. MLT is truly driven by economics and restrained only by imagination. Perceived risks may by high, but the payoff is much greater.

The author
	Jim Oberkircher is the business development manager for Sperry-Sun Multilateral Systems in Houston, Texas. He graduated with a BS in mechanical engineering from Carnegie-Mellon University and has spent the last 20 years in the oil industry, the last several in the area of multilateral drilling and completion systems. An author of many publications, he has been active in SPE and SPWLA. His e-mail address is jim.oberkircher@halliburton.com.