Improved production log interpretation in horizontal wells using pulsed neutron logs
Production log flow profiles provide a valuable tool to evaluate well and reservoir performance. Horizontal wellbores and their associated completion designs present several challenges to profile interpretation for conventional production logging sensors and techniques. A unique approach combining pulsed neutron capture (PNC) log data with conventional production logging measurements is providing improved flow profile answers in slotted liner, horizontal well completions on the North Slope of Alaska. Identifying and eliminating undesirable gas production is one of the chief goals of production logging on the North Slope. This process becomes difficult in horizontal wellbores as fluid segregation affects the area investigated by the various logging sensors and also the velocities of the individual phases. Typical slotted liner completions further complicate analysis as fluids are able to flow in the liner/openhole annulus. Analysis of PNC log data provides two good qualitative indicators of formation permeability. The first technique is derived from the difference of the formation sigma response before and after injecting a high-capture cross-section borax solution. The second technique uses the difference of the formation sigma response and the formation porosity measured while injecting the formation with crude or seawater. Further analysis of PNC log runs show that the two techniques closely correlate with production flow profiles under solution gas-oil ratio (GOR) conditions. These two techniques in combination with conventional production logging measurements of temperature, capacitance, pressure, and spinner improve flow profile results. PNC results can be combined with temperature and pressure data in the absence of valid spinner data to provide an approximate flow profile. These techniques have been used to successfully determine profiles in both cemented and slotted liner completions with GORs in excess of 15,000 scf/bbl.
- OSTI ID:
- 468248
- Report Number(s):
- CONF-961003-; TRN: 96:006577-0053
- Resource Relation:
- Conference: 71. annual technical conference and exhibition of the Society of Petroleum Engineers, Denver, CO (United States), 6-9 Oct 1996; Other Information: PBD: 1996; Related Information: Is Part Of 1996 SPE annual technical conference and exhibition: Production operations and engineering/general; PB: 892 p.
- Country of Publication:
- United States
- Language:
- English
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