Show closely drilled gas fields according to the united states geology ai survey department of the interior over 61 rilling illing is strikingly evident in the clove and d ohio gas field where it has led to considerable onside rable financial loss I 1 ohio has long been a large producer f natural gas but the gas in cuyahoga Cuya hoga founty which is in the northeastern part if the state has only recently been com ercia lly exploited the exploitation of he e cleveland field began early in 1912 with the he completion of several successful wells in n the western part of the city of cleveland nd within four years more than wells ells most of which struck gas had been shrilled in an area of about 25 square miles the excessively close drilling in many parts of this area has resulted in a rapid decline of the output of individual wells nd and the older part of the field is destined to be short lived this field is of interest because it is close to a great manufacturing city that has long been a consumer of large quantities of natural gas and the uneconomic meco character of its development is ihus bus especially unfortunate the geology of gas accumulation most of the wells in the cleveland field draw raw their supplies from the so called linton clinton sand a productive reservoir of gas that hat lies in a belt extending southward through the east central part of the state Ll though no evidence has yet been found coshow 0 show that the cleveland field is directly connected with these fields it is at the northern corthern extremity of the same structural belt elt and is geologically related to them hiring during the latter half of 1915 the cleveland field eld was as extended somewhat to the southwest into a region where prospecting is now ow most active A small pool has been exploited just south of berea which lies fourteen arteen miles southwest of cleveland and further arther extensions in that direction would connect the cleveland field with the belt of f fields to the south geologic structure has evidently been the ie broad controlling factor in the accumulation of gas in the cleveland field though the ie porosity of the gas sand has also played a 11 important part A knowledge of the factors victors that have led to the accumulation at t cleveland should be of value to those who ho are attempting to find extensions of the ie field biow OW many gas wells to the square mile one of the most important problems con fronting the gas producing industry is that of t determining the smallest number of wells ells capable of removing most economical ay r all the gas under a given tract of land go 0 many complex factors enter into this problem that few systematic attempts have ave been made to solve it and gas oper acors have in general been content to accept rough estimates of the number of wells that should be drilled per unit of area in some localities it is held that only one well should be drilled to each acres in others it is customary custo maey to drill a well in each twenty or of forty acres with present knowledge the number to be drilled must be to some extent a matter of opinion and it is very doubtful whether any limit can be fixed that will be applicable to all fields those who are familiar with the gas industry have long realized that a closely drilled field is short lived and that in most pools the later wells are less likely to be profitable than the earlier ones few operators however have attempted tu to analyze the reasons for these conditions and most of the business men and others who are occasionally induced to take a flyer in gas producing seem to be ignorant of the existence of them hence in many eastern gas fields there are more wells than are necessary or profitable and in some fields the wells are crowded so closely that many of them have never produced enough gas to pay for themselves the flow of wells A study of the available records of rock pressure and flow of wells in the cleveland field indicates that the decline of rock pressure in the older wells is a valuable criterion in controlling new development probably in most fields the wells that are brought in after the general pressure has declined to one third of its original amount are unprofitable and in many fields this point may be reached when the pressure has declined only one half the geology of the cleveland field in relation to the accumulation of the gas has recently been investigated by the united states geological survey and is discussed in bulletin A entitled the cleveland gas field cuyahoga Cuya hoga county ohio with a study of rock pressure by G sherburne rogers A copy of this report may be obtained on application to the director of the geological survey washington D C |