FLOODING OF PETROLEUM WELLS.

Taranaki Herald, Volume LXII, Issue 144351, 16 March 1914, Page 6

FLOODING OF PETROLEUM WELLS.

*0 THE EDITOB. Sir, —For some time past there has appeared in tho columns of the Herald correspondence on the above subject. There has also boon a complaint to Government by one petroleum company that their well (or boro) was flooded by water from the disused bores of another company, also a report on this complaint by the Government Geologist (which, by the way, has befogged tho thing more than ever), and you through your editorial, columns have endeavoured to lot a little light into the darkness. But so far there has been nothing to explain to the man in the street who takes, an interest in petroleum as to why water lying in a disused well takes upon itself to invade another well at a distance of 100 ft., or 100yds., or any other distance. I have studied hydrostatics to some extent, and have though a good deal about this flooding business, but cannot arrive at any satisfactory conclusion on the matter. To my mind as a layman (not a petroleum expert), it seems that water can get into a petroleum bore or well only from ono or more of tho following causes: (a) From surface drainage (that is. from surface flood water during heavy rains) pouring into the bore as down a drain; this can at once bo dismissed, as no sane company would permit of such a thing; (h) from the nitration of water held in suspension in the subsoil (volcanic tufa) and gravel bods lying between the surface and the impermeable papa stratum below it; (c) from filtration of oil mixed with water in the porous sandstone or other oil-bearing strata below the papa; (d) from water in the caverns, seams, or peckers Iving under or with the- oil. Now. it will at once be admitted, as regards (b), that our subsoil, whether earth or gravell holds in suspension variable quantities of water, more, of course, in wet weather than in dry. but always some; if you sink a well or bore a large or small hole deep enough, water will filter into that well or hole and remain there to the level of the suspended water in the soil, rising in wet weather and falling in dry; but if you sink another well or bore another hole—say 100 ft. away—tho first hole will not empty itself into the second, hut suspended water from tho soil will fill No. 2 as it filled No. 1, and the whole will, under .ordinary conditions, arrive at a level or balance. The same thing applies to (c), with this difference, that a pressure of gas may come into piny, forcing tho water aud oil to a higher level than it otherwise would lie atp if raised to a sufficient height tho weight or pressure of tho column of water and oil would have a tendency to force some of it horizontally through tho pervious soil or strata; hut this would soon be checked by the resistance or. friction of tho soil and by the soil being choked or sealed with congealed oil or paraffin; water would thus bo prevented from being forced sideways in any appreciable quantity. Under pressure of suspended water in the so: 1 towards the bore, as in (b), this might force tho congealed oil inwards, but tin's very pressure would prevent anv water getting out; tho column would balance as before. (D) differs from (c) only by the fact that if your boro enters a pocket, scam, or cavern containing oil and perhaps water, there will certainly be a pressure, large or small, of compressed gas lying upon the oil, which will force the oil. and perhaps water, up the bore to the surface, oi to a height corresponding to the pressure below. Now, these conjectures ot mine do not clear up the matter one hit, if it is line—which I take leave to doubt—that water in ono bore can How through 100 ft. or 100yds., or more or loss of soil or rock to another bore, how is it done? Water will not flow .against gravity, aud hut slowly against I notion; you cannot make it run uphill unless von have a sufficient force behind it, amf the mere collection of a quantity of water in a small bore—small in comparison with the mass of surroumlinc earth or rock —cannot destroy the cqTlihriuni of the suspended water in the soil or strata all around it Can von, Mr. Editor, or Mr. Griffiths, or Mr Fedorowicz or any other petroleum expert, elucidate this matter? I confess I am 1 I /.a I A'A).