horizontal drilling at snatcher

As a long time petroleum explorationist, I thought I would put down a few thoughts on directional drilling with reference to Snatcher 1.

In its simplest form;

a vertical well intersects each rock layer once and produces oil radially typically sweeping 40, 80 or even 160 acres surrounding the well depending on the reservoir.

a horizontal well goes down vertical and then turns horizontally in time to penetrate the zone at nearly 180 degrees. The length of the horizontal section is typically 400-2000m. While much more costly and more diffult to complete, horizontals are the best choice in selected situations.

Leaving aside the difficulties in predicting where to exactly place the horizontal section, horizontal wells are not always the best option due to geology.

Horizontals are most useful where the reservoir is continuous but compartmentalized by faults, is simple in structure and/or less permeable than most reservoirs. In these cases the horizontal well can access a large section of the reservoir and even if each part of the well does not drain oil from very far or does not drain oil very fast; the length of the section through the reservoir produces oil at an economic rate and sweeps oil all along the reservoir even from compartments seperated by faults.

Horizontals do not work when the reservoir is sporatic, when the horizontal section goes through wet reservoir (water is less viscous than oil and will preferentially be produded - killing the well) and are not economically the best choices when a safer, cheaper vertical well will sweep the reservoir.

If the Snatcher reservoir is a channel (think exposed and buried sand bars along a river), the reservoir is likely to be laterally discontinuous.

If similar sands have been produced at rates in excess of 100 bopd and are being successfully radially drained by vertical wells, then horizontal wells are not needed.

A surgically placed vertical well in the thickest most porous/permeable part of the reservoir would be the optimum exploitation strategy.