Monitoring the effects of sand production on a more permanent basis is accomplished by installing downhole sensors that record bottom- hole fl owing pressure and temperature, offering real-time monitoring and control capabilities (previous page).35
Real-time data from downhole,
subsea and surface sensors can be delivered using the InterACT real-time monitoring and data delivery system to update modeling and sim- ulation tools, such as ECLIPSE reservoir simulation software.
When Reservoirs Fail
Many completed and producing wells are experiencing sanding problems. Sand production can be relentless, with damaging effects on production rates and hardware. Early detection through monitoring can detect problems and prompt intervention before problems become severe. However, sometimes catastrophes occur unexpectedly and result in total well failure and a need for intervention. When inter- vention is necessary, comprehensive sand- management practices help determine the best action.
When appropriate data— production, well-
test, core and log data— are coupled with sand-production and well-history information, the need for, and the value of, remediation and production-enhancement efforts can be evalu- ated. In wells with multizone completions, proprietary Schlumberger production-allocation software allocates production for each zone using production-log data. This allows engineers to evaluate each zone separately, making remedial treatments more selective.
In hydraulically fractured wells, proprietary ProFIT production analysis software helps deter- mine fracture properties so that problems that limit fracture effectiveness can be diagnosed and remedied. Lastly, ProCADE software allows the analysis of well-production data to determine near-wellbore reservoir properties and to predict well performance as the completion scenarios change. These powerful software tools can predict the impact of remedial efforts to gauge both the economics and risks.
34. Carlson et al, reference 7.
Olesen J-R, Hudson TE and Carpenter WW: “ Gravel Pack Quality Control by Neutron Activation Logging,” paper SPE 19739, presented at the 64th SPE Annual Technical Conference and Exhibition, San Antonio, Texas, USA, October 8– 11, 1989.
35. Al-Asimi M, Butler G, Brown G, Hartog A, Clancy T, Cosad C, Fitzgerald J, Navarro J, Gabb A, Ingham J, Kimminau S, Smith J and Stephenson K: “ Advances in Well and Reservoir Surveillance,” Oil eld Rev iew 14, no. 4 (Winter 2002/2003): 14– 35.
36. Acock et al, reference 11.
Well-intervention techniques vary in type and cost. An operator may choose a screenless method that does not require a rig, such as adding perforations, reperforating or hydraulic- fracturing techniques.36
In some cases, vent
screens can be installed without a rig. Major operations requiring a rig, like gravel packing or installing expandable screens, may be needed to achieve the best result, but these operations add costs.
When well economics justify recompletions,
many sand-exclusion and sand-prevention methods again become viable options. For this reason, recompletions mark a new opportunity for operators and service providers to incorporate the informed decision-making process associated with thorough sand- management practices.
The Sands of Time
Sophisticated sand-screen and gravel-packing tool designs have drastically improved the sand- exclusion process, adding life to wells and reserves to assets. A new sand-exclusion system called expandable sand screens represents a fun- damental shift in methodology. As part of the true monobore, or monodiameter, vision, expand- able completions provide an effi cient, single-trip alternative by expanding out to the borehole wall to reduce the annular space, thereby reducing annular flow, maximizing borehole volume and stabilizing the borehole wall. The technology eliminates the need for other tubulars and gravel packing, and it potentially offers higher produc- tivity than cased-hole completions. While there have been mixed results with expandable-screen completions, the technology continues to evolve rapidly, and so far, its applicability has primarily been in horizontal wells that produce from well- sorted sandstone reservoirs. Technological advances across all facets of sand management— prediction, prevention, monitoring and remediation— refl ect the scale of the problem and the importance of solutions. Modeling tools that predict when reservoir sand- stones will fail help E&P companies address problems downhole by preventing sand failure using screenless methods or by impeding the migration of sand into the flowstream. Schlumberger continues the quest to more fully understand perforation and borehole geome- chanics, and to continue to develop innovative perforating, fracturing and sand-control comple- tion solutions.
The ability to predict surface sand volumes
accurately would be helpful. However, this remains a daunting challenge, especially in highly deviated and horizontal wells, because it requires that all modes of sand transport be con- sidered. Moreover, there are added complexities in accounting for completion types and for vary- ing flow regimes. Improving sand-monitoring techniques and learning how to better exploit monitoring data in models and simulators may be a more practical approach. As with other oilfi eld challenges, addressing sand-production issues will require the collabo- ration of experts, the development of effective and effi cient processes, and the appropriate use of technologies. Producing hydrocarbons from weak reservoirs is a tricky business because the unknowns outweigh the knowns, but the balance is clearly tipping towards more production with less sand.
— MGG
Spring 2004
27
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76