A number of small MWDs and steering tools are available, mainly intended for the horizontal sidetrack market. There are a number of small gyros which were designed to be run through conventional drillpipe. Dip-meters can be used as surveying instruments.

Alternatives to surveying for cost-effective wells

For many cost-effective vertical wells, surveying the well to a “high” standards represents a significant proportion of the total well costs. The provision of surveying services, especially in remote areas, may outweigh the perceived benefits. For example, if the well is a rank wildcat, from a geological perspective accurate knowledge of the bottom hole location may only be required if testable reserves are discovered. If the well is dry then 'Totco' type inclination only surveys may be adequate dependent on relief well drilling criteria. So long as the well is close to vertical the depth uncertainty of the horizons of interest will be small. In such a case to minimise the cost of a dry well, the surveying services might only be mobilised with the production test equipment.

However, there always remains the very low probability of a blowout which cannot be capped and which therefore requires a relief well. One low cost solution could be to magnetise the shoe joint of each casing/liner and the lower DC/Motor of each BHA. This would ensure that a relief well could be homed in to the casing shoe or BHA from a larger range than if the target were not magnetised however it is not a guaranteed method and the relief well drilling criteria still apply, i.e. a total error of less than 15 m. It should be noted that the range for magnetic detection in both cases is smaller than with conventionally sized wells as the strength of the magnetic pole(s) are related to the size of the tubular.

It would of course be up to the management to balance the cost and time savings through not surveying against the possible increased time to intersect the blowing well with a relief well, and the uncertainty in the location of any geological markers.