Whether in deep wells, shallow water well completion or onshore shale wells, the key problem to promote its further development currently are technology simplification and integration. Oil and gas production changes quickly. In less than 6 years, the boom of oil shale industry has witnessed the oil production of Bakken shale as much as 6 BbbL. Intelligent well completion in the future will be an integrated solution, the solution makes a variety of downhole hardware develop to the desktop through the production facilities.

No matter the deep well completion technology, horizontal well completion redesign, or a newhydraulic fracturing technology and well completion technology of shallow waters, the oil and gas industry has been constantly looking for ways to improve. For example, the oil company must decide whether to repeat fracturing well, which will be a feasible and effective economical choice. As part of the well completion technology progress, the oil companies must focus on finding out the location of well completion whose quality has not been optimized. And improve oil recovery from conventional well completion. Refracturing existing wells cost is a small portion of new well drilling cost.

After the accident of Macondo well drilling in the Gulf of Mexico (GoM), the oil and gas industry pay more and more attention to the well engineering. The U.S. department of energy's national energy laboratory is trying to uncover how the bubble cement affects engineering of oil wells in the deepwater. They set up a team to make a thorough assessment on deepwater cementing of existing research results. Through the study, five research areas need further analysis.

Offshore and onshore well completion can progress unceasingly to meet the needs of the oil and gas industry. Although the Gulf of Mexico deep-water exploration spend a lot of money, but industry turned its attention to the shallow waters outer continental shelf. A new generation of diver auxiliary oil drilling tree is specially designed for jack-up drilling platform developed under sea.

With the increasing use of hydraulic fracturing, tree continues to develop. The decline of fracturing tree height and the increase of its quality and safety improvement has led to lower drilling cost. In the end, the intelligent well completion technology has walked a long way since the 1990s, and the new system is trying electronic and optical fiber to avoid the complexity of wellhead hydraulic pipeline.

Refracturing increase return on investment

Unconventional oil and gas wells may have better prospects than previously estimated. We know that a well is not easy to complete optimization at the first time, and as the declining production and oil and gas reservoir is still in situ, oil companies must decide whether refracturing is a feasible solution.

Weatherford hydraulic pump market sales director Francisco Fraga Chan said: "Considering closing wells and refracturing, it is difficult to make a decision. There is a risk, and that is why we continue to focus on reservoir well whose quality is not optimized. At present, we have to get more experience, let our customers become more confident on the technology.”

Baker Hughes refracturing production line and multistage mining system manager, Juan Carlos Vlores said that completion production falling precipitously is characteristic of unconventional shale well today, after initial completion, its general production only 3-8% of the estimated reserves.

In fact, what we should focus on is to provide more effective wells for oil companies to improve the ultimate recovery factor. We know that refracturing can recover even more than the initial production, and the same wells can change several times, which will need designed completion projects to maintain the unconventional production life cycle.

Determine the feasibility of refracturing

We know that each well is unique, and no matter now or in the future does not exist a "universal" solution to improve recovery factor.

Analysis of economic benefits in advance with oil companies and understanding of reservoir is one of the key linksof the process of operation. Therefore, the characteristic of well drilling and well completion and reservoir characteristics must be understood deeply. Wecan generate the forecast modelaccording to theinformation, so as to display and estimated potential rewards of every horizon, and make refracturing plan further according to the best goal of the most suitable company.

It is a completely different way with picking a small accessory in a hardware store. It requires us to understand the needs of customers, and work closely with the client to determine the optimal solution based on data driven method and careful plan.

Communication is crucial. Oil companies should understand in advance that not all wells refracturing and recompletion are successful. First thing to do is to ensure that the drilling is appropriate and refracturing is very meaningful. So, we should choose a reservoir with good properties as a suitable drilling target firstly.  Secondly, we should consider the possibility of steering in the process of fracturing treatment, and must provide an opportunity to improve the efficiency of completion.

Before the fracturing to newposition, reservoir must be sealed. By adopting the most suitable technology and craft, blocked reservoir will eventually recover. Previous production can be together with new fracturingposition production, sometimes even can significantly increase the overall productivity of drilling. However, refracturing is a complex mixed operation, and it has to consider the natural reservoir heterogeneity.

When multiple entry points arefractured, the fracture energy tendsto flow in the path of least resistance. After fracturing, then it is difficult to transfer the energy into another entry point.

In fact, changing direction is the main challenge of fracturing fully, which is the key to select appropriate technology. It explains why not all wells are suitable for refracturing operation.

Intelligent well completion technology

From the whimsical idea to being a reality, intelligent well completion continues to challenge the limit. Its concept has many names of "intelligent drilling", "underground factory" and "future oilfield". These names describe a new form of well completion technology, and provide better way control to their ability of oil and gas well downhole to the oil companies .The term "intelligent well completion" is often used to describe various technologies which meet the demand of oil companies in the past 10-15 years .In the early stages of the concept, it is a great idea.

"These fully autonomous regions’ initial vision is the ability to control itself, and to provide the optimization ability, have wireless communication into the wellbore."Baker Hughes’ director of intelligent manufacturing system Darrin Will auer said.

But there are some compelling driver factors. First of all, the drilling technology is undergoing great changes."Industry key challenge is how to drilling, and how to maximize contact with reservoir, " well completion technology market manager of Schlumberger Xavier Dana said: "We begin from horizontal wells, followed by large displacement wells, now is the branch wells."Drilling technology is developing rapidly from the beginning, and now it has become a common practice, which cannot be achieved in the 1980 s and 90 s. At the same time of development, there are many challenges."We can drillwells, but how can we complete the drilling and effective production? Obviously, the current completion technology is inappropriate."

Another driver factor is that well accident costs continue to rise, especially on the sea."People don't want to move the casing, because they want to block out of the water," Halliburton intelligent fluid control senior product manager, Savio Dana said, "It means they have to move the drilling platform just for moving the casing .Considering the high operation cost, there is no economic sense."

It is horizontal well and branch well getting the difficulty of production logging that drives the need for intelligent system. Only native borehole in branch wells drilling can be recorded."There can be four or five branches in the same well, but we can't ignore these wells production."Savio Dana said.

Therefore, the intelligent well completion technology made a great progress. Early stage is relatively simple, just to combine the flow control valve and pressure temperature sensor together. Over time, these systems have become more and more complex, but they are of great benefit to the development of oil and gas industry.

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