− | [[file:applying-gravity-in-petroleum-exploration_fig15-15.png|thumb|{{figure number|4}}(1) Model of laterally homogenous geology and no density anomalies. (2) Region of lower density, possibly signifying the presence of missed hydrocarbons [[length::60 m]] from the well. (3) Low-density missed pay zone within [[length::15 m]] of the well, with a strong density difference. (4) Missed pay about [[length::1 m]] from the well; the density difference is very pronounced. From Bayer;<ref name=ch15r1>Beyer, L., A., 1991, [[Borehole gravity]] Surveys: SEG Short Course notes, June, 350 p. Excellent source for general principles of borehole gravity. Very good figures and references.</ref> Copyright: SEG.]] | + | [[file:applying-gravity-in-petroleum-exploration_fig15-15.png|thumb|{{figure number|4}}(1) Model of laterally homogenous geology and no density anomalies. (2) Region of lower density, possibly signifying the presence of missed hydrocarbons 60 m from the well. (3) Low-density missed pay zone within 15 m of the well, with a strong density difference. (4) Missed pay about 1 m from the well; the density difference is very pronounced. From Bayer;<ref name=ch15r1>Beyer, L., A., 1991, [[Borehole gravity]] Surveys: SEG Short Course notes, June, 350 p. Excellent source for general principles of borehole gravity. Very good figures and references.</ref> Copyright: SEG.]] |
| Because the borehole gravity meter is the only tool that can measure bulk density away from the borehole, it is ideal to use for finding bypassed pay zones. In [[:file:applying-gravity-in-petroleum-exploration_fig15-15.png|Figure 4]], Case #1 shows a model of laterally homogenous geology and no density anomalies. Case #2 shows a region of lower density, possibly signifying the presence of missed hydrocarbons [[length::60 m]] from the well. The density difference detects the distant density contrast as a broad, anomalous low with its minimum centered at the correct depth. Such a zone may be within range of a borehole sidetrack. In Case #3 the low-density missed pay zone is within [[length::15 m]] of the well, and a strong density difference exists. Such pay zones may be in the range of a possible [[well completion]] after hydrofracturing the reservoir. In Case #4 the missed pay is about [[length::1 m]] from the well, and the density difference is very pronounced. Such pay zones are within the range of normal [[well completions]] but would still be undetected by any other logging method. | | Because the borehole gravity meter is the only tool that can measure bulk density away from the borehole, it is ideal to use for finding bypassed pay zones. In [[:file:applying-gravity-in-petroleum-exploration_fig15-15.png|Figure 4]], Case #1 shows a model of laterally homogenous geology and no density anomalies. Case #2 shows a region of lower density, possibly signifying the presence of missed hydrocarbons [[length::60 m]] from the well. The density difference detects the distant density contrast as a broad, anomalous low with its minimum centered at the correct depth. Such a zone may be within range of a borehole sidetrack. In Case #3 the low-density missed pay zone is within [[length::15 m]] of the well, and a strong density difference exists. Such pay zones may be in the range of a possible [[well completion]] after hydrofracturing the reservoir. In Case #4 the missed pay is about [[length::1 m]] from the well, and the density difference is very pronounced. Such pay zones are within the range of normal [[well completions]] but would still be undetected by any other logging method. |