Conventional practices have focused on controlling sand in-situ using a variety of methods. Gravel packs in the 1970s and 1980s followed by frac packing in the 1990s were considered state-of-the-art solutions. Projections now show that half of future hydrocarbon production will come from reservoirs prone to sand production. Furthermore, the industry’s needs have evolved to more complex completions, requiring a concentration of new technologies and expertise.

According to the 2006 Spears report, overall sand management expenditures, including sand
 
Figure 1. Sand Management key influence roadmap. (All graphics courtesy of Schlumberger)  
control tools, screens and pumping, are estimated at US $2 billion. Spending is forecasted to nearly double in the next 4 years. Some key industry trends and influences (Figure 1) contributing to the growth are increases in subsea and deepwater activity, increases in the number of horizontal and extended-reach wells, and the emergence of the high-pressure and high-temperature market.

Economic drivers include rising rig costs as well as the cost of deferred production. In addition, efficiency is paramount as completion time equals or exceeds drilling time. So any procedure with the potential to eliminate or delay future well interventions deserves industry attention. The evolution of innovative sand control techniques testifies to the complexity of the problem and the need to balance economics and productivity.

Engineering sand management
Predicting wells’ probability to produce sand hinges on many factors. Principal among these is rock mechanics, but the type of well and the way it is drilled, completed and produced also
 
  Figure 2. Current market trends show increasing expenditures in openhole completions.
plays a critical role. There is no “one size fits all” solution. The industry requires a robust, flexible engineering process whose objective is to customize and apply the best sand management system for each well — one that makes sense technically and economically. Principal components in a multidisciplinary approach involve predicting if and when sanding will occur and identifying the conditions that precipitate the problem. The predictions are based on reservoir measurements that include analysis of the rock matrix, type and characteristics of fluids to be produced, and the dynamic forces acting on them. Only then can a comprehensive plan of completion techniques be put forward that will protect against sand production over the life of the well. Jumping to a solution without first performing this analysis can negatively impact production and completion longevity.

Prevention is a fundamental component of sand management. This phase begins with implementation of designs indicated by the prediction phase. Solutions range from establishing and maintaining production parameters such as flow rate and drawdown that are below threshold levels for sand production to installing complex mechanical exclusion techniques. These include openhole gravel packs, standalone screens, cased-hole gravel and frac packs, screenless completions using fracturing with proppant control, or oriented perforating.

Sometimes a combination of techniques may be appropriate.

Real-time monitoring is necessary because reservoir conditions are subject to change over
 
Figure 3. Increase in deepwater completions represented by the number of subsea wellheads per year.  
time. By measuring drawdown pressure, flow rate and flow stream properties during production and using trend analysis, operators can predict the onset of potentially dangerous conditions as well as monitor the effectiveness of the completion. Electronic remote surveillance procedures can also be initiated so entire assets are efficiently managed. In the future, sand management measurements will be added to production data for transmission to a central control hub.

If a well is already producing sand, or if sanding commences despite all efforts to prevent it, remediation treatments can be performed to correct the problem. These treatments can be implemented through tubing and include gravel packing, fracturing with proppant flowback control and installing a screenless completion.

Openhole solutions show promise
The evolution of drilling technologies has led to an increasing number of horizontal wells; and openhole completions are on the rise (Figure 2). This is linked to the exponential growth in deepwater and subsea developments (Figure 3), which require an extended completion planning cycle in excess of 3 to 5 years.

Another factor is the growing demand of reservoir pressure maintenance by water or gas injection. On the latest deepwater developments, the ratio has increased to one injector well
 
  Figure 4. Typical openhole gravel pack completion and pumping treatment.
for every two producers. Openhole completions, due to the associated low skin values, are also becoming a sound solution. With the development of less damaging drill-in fluids and advances on filter cake clean up techniques, openhole wells have lower injection pressures than cased and perforated wells.

A significant portion of the growth in openhole completions comes from gravel pack (Figure 4). Dedicated equipment such as openhole service tools, washpipe diverter valves and supporting chemistry such as a shale stabilizer and friction reducers have been developed to overcome the original limits and increase reliability of the existing gravel packing techniques. These new technologies complement the existing water pack and alternate path systems.
Openhole zonal isolation packers and inflow control devices, whose purpose is to equalize reservoir inflow across long horizontal screens to reduce water or gas coning, have been introduced to improve completion versatility and reservoir management.

A line in the sand
Schlumberger has considerable experience in all segments of sand management, and experience teaches us that no problem can be resolved in a vacuum. Recently, the company launched an initiative to develop a unique business line of Sand Management Services integrated with production optimization techniques and executed by a coordinated field team having deep experience in pressure pumping and completion services. 

Worldwide sand management
The threat of sand production is felt worldwide, but there are too many variables — no single solution will do. By applying the principles of prediction, planning, prevention, monitoring and remediation we can resolve sand problems while optimizing production and extending the economic life of valuable assets.