Mr. Erik Milito - The House Committee on Natural Resources ...

Annex B
(informative)
Well Planning and Drilling Plan Considerations
B.1 Evaluation of Well for Flow Potential
B.1.1 General
Before drilling a well, the operator should attempt to identify and analyze potential flow zones. A variety of techniques
are available to do this, three of which are discussed below. <strong>The</strong> success of these techniques in identifying and
successfully dealing with flow zones is related to the quality of the available data, a company’s experience in a
specific geographical area, and the capabilities of the personnel involved in the analysis.
B.1.2 Site Selection
Prior to drilling, the operator can minimize encounters with potential flow zones by carefully selecting a site that
achieves target depth while minimizing the risk of encountering a flow. This is accomplished primarily through
accurate review and analysis of available shallow and deep hazards data, proper interpretation of this information,
and assimilation of this information into the drilling program.
Offset well information (when available) can be evaluated to determine if flow zones were encountered, the
magnitude of any flow events, and the methods used to mitigate the effects of these flows. This information should be
incorporated into the current drilling program.
API RP 65, Section 4, addresses site selection for minimizing shallow flows in deepwater wells. Many of the same
principles apply to operations for all water depths and well depths and are discussed below in this Annex.
B.1.3 Shallow Hazards
Identification and evaluation of hazards through the use of shallow seismic surveys obtained over potential wellsites
can aid the operator in proper site selection. If available, shallow seismic data from offset wells or adjacent fields
where shallow flows occurred should be used to verify the analysis. If hazards are identified, the risk should be
evaluated and mitigation measures taken as appropriate. <strong>The</strong> operator is cautioned that a shallow hazards analysis is
not a conclusive method of prediction, so precautions to minimize the probability of a flow should still be implemented
when drilling the shallow portions of the well. If the decision is made to drill a well in an area that is likely to encounter
shallow hazards, drilling the shallow portions of the well with a small diameter pilot hole will make killing the well
easier to achieve.
B.1.4 Deeper Hazards
Potential sources of deeper drilling hazards include abnormal pressure, pressure depleted zones, faults, tectonic
stresses, salt flows, and lost circulation. Such hazards can often be identified through seismic interpretation and/or
analysis of offset wells or fields. Identification of hazards that could be encountered during drilling operations will aid
in proper well planning and in minimizing risk. If available, deep seismic data from offset wells or adjacent fields
should also be analyzed to aid in the prediction of flow zones.
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