9 Localización y resolución de problemas básica
9.1 Arranque y funcionamiento
In this Section...
• Wellbore Considerations - Planning Well Profile
- Mud Design & Hole Cleaning Issues - Drilling Reservoir Section
- Displacements • Completion Types
- Extended Reach / Horizontal Well Completions for Sand Control - Gravel Packing / Fracpacking
- Frac Pack Completions - Designing Upper Completion - Running Upper Completion
- Damage Removal in Extended Reach / Horizontal Wells - Matrix Stimulation
• Well Interventions - Open Hole Logs/RFT - Cement Evaluation - Perforating
- TCP
- Running & Pulling Completions - Production Logs
- Water/Gas Breakthrough Management - Coiled Tubing
• Artificial Lift - ESPs • References
INTRODUCTION
The numerous extended reach / horizontal well completion methods available offer varying degrees of efficiency in the ability to manage the reservoir through the wellbore(s). These methods vary from extremely basic to the more complex. It is always important to keep in mind the concerns and practices used in vertical well completions. These concerns relate to drilling through the interval with a mud system that either produces minimum damage or a damage that is easily removed by perforating or low cost stimulation, to having sufficient zone isolation for stimulation and future work in the vertical well. It is important to have these same or greater concerns with extended reach / horizontal wells. The ability to manage the reservoir through these wellbores is important to the success of the well.
Table 4-1 points out some of the many variables which are important in obtaining the proper completion and, therefore, production from an extended reach / horizontal well. These are divided into three main areas as shown below:
• Reservoir Characteristics - These characteristics are divided into primary and secondary importance and both can dictate completion design.
• Wellbore Considerations - These considerations are divided into the radius of curvature for the well path and diameter of the drilled hole; and wellbore stability. The radius of curvature and diameter of the drilled hole will influence selection of equipment and tools that can be used upon completion and subsequent workovers. Wellbore stability will influence the mud weight and chemistry used to drill the well (and formation damage) and to the wellbore stability at drawdown (production).
• Completion Type - The selection of completion type will be based upon the reservoir characteristics, wellbore considerations and economics and can become an iterative process. That is, when the expected results are determined and compared to the cost and complexity of the completion, a different approach, perhaps shorter lateral length, assumption of a higher degree of risk (poorer completion design) or even a decision to not drill the well can be considered.
These variables point out that the process of drilling and completing extended reach or horizontal wells takes into consideration many disciplines. A multidisciplinary team effort is necessary to develop the final guidelines as to how these wells are to be drilled and completed. It is also evident that in many cases there is no definite separation between drilling and completion operations with these types of wells. The final running of the liner and washing the wellbore may also be the completion. The completion method must fit the reservoir characteristics and drilling parameters employed.
TABLE 4-1
ER AND HORIZONTAL WELL COMPLETION CRITERIA
EXAMPLE
Reservoir Characteristics Wellbore Considerations Completion Type Primary Secondary Radius/Dia Stability
Natural Fracs Normal PP Ultra Short Drill OB Open Hole
Water Coning PP>Normal Short Radius Drill UB Slotted Liner
Gas Coning PP<Normal Medium R Drill B Preperfed Liner
Unconsol Carbonate Long Radius Stable @ DD ECPs / SL
High Perm Sandstone Slim Hole Cased Hole
Low Perm Shale Wire Wrapped Screen
KH / KV Gas PrePacked Screen
Thin Beds Oil OH Gravel Pack
EOR CH Gravel Pack
PP = Pore Pressure DD = Drawdown
R = Radius ECP = External Casing Packer
OB = Overbalanced SL = Sliding Sleeves
UB = Underbalanced OH = Open Hole
B = Balanced CH = Cased Hole
Other factors not shown on the table also influence the completion type. Two of these are the effect of only having a portion of the horizontal wellbore open to production and the pressure drop expected along the horizontal well during production.
• Partially Opened Wellbore - Goode and Wilkinson reported in their work, that it may not be practical or cost effective to open the entire length of the lateral.