Post by Ethan / JRyan on Mar 6, 2019 20:01:34 GMT -5
Heletz Field
What is it and where is it?
What about it and what information is there?
Wiki
Keep in mind that this was a conventional Oil field, from the 50's.
Snippet of info
links:
Origin of Oils in Helez Region, Israel--Implications for Exploration in the Eastern Mediterranean
Oil prospects of the helez formation, southern hashephela region, Israel: Evaluation of the thoroughness of search achieved by past exploration
What is it and where is it?
What about it and what information is there?
Wiki
The Heletz oil field is an Israeli oil field that was discovered in 1955. It is one of the biggest on-shore oil fields in Israel. It began production in 1960 and produces oil. Its oil proven reserves are about 94.4 million barrels (15.01×106 m3).[1]
Snippet of info
links:
Origin of Oils in Helez Region, Israel--Implications for Exploration in the Eastern Mediterranean
Oil prospects of the helez formation, southern hashephela region, Israel: Evaluation of the thoroughness of search achieved by past exploration
Oil Prospects of the Helez Formation, Southern Hashephela Region, Israel: Evaluation of the Thoroughness of Search Achieved
by Past Exploration 1
D. Gill 2 and R. Gabai 2
To what extent have the possibilities been exhausted of discovering concealed subterranean natural resources in a given area? Stated differently, and employing a positive or optimistic viewpoint (the half-empty vs the half-full glass analogy): What are the chances that, in an area which was already tested by some drillholes, a target of a given size has been left undetected? The answer hinges on
two independent sources of information: geological considerations and the level of exploration or the thoroughness of search. By the very nature of exploration ventures, definitive knowledge about the geological favorability of any given point in the explored area is always lacking. To circumvent this inherent difficulty it is constructive to assume, at least as a first step, that if resource targets
exist, their distribution is uniform so that they are equally likely to occur anywhere in the area. Under this simplifying assumption the answer to the above question is a function of the geometry (size, shape, and spatial orientation) of the target being sought and the geographical distribution of past exploratory tests. Each test (e.g., drillhole), whether successful or not, exhausts a certain area
in its immediate geographic neighborhood in the sense that within it, resource targets could not have existed without having been found. The amount and disposition of the exhausted area is a function of the target's geometry, as mentioned above. Each new test reduces the size of the remaining prospective area. The state of areal exhaustiveness of a region (or its prospectiveness-the positive
complement of exhaustiveness) can be evaluated by the mathematical method developed by Singer and Drew (1976). The results obtained are displayed in isopleth contour maps in which the value at each point specifies its degree of exhaustion. For example, a value of 0.5 means that if an elliptical target is centered at this point, 50% of its possible orientation would have been found by
past drill holes. Additional geological considerations can then be brought into account and after proper translation into an inferred geological favorabflity function, these considerations can be integrated with the areal exhaustiveness data
to formulate an optimal search strategy.
Using program RESIN (Singer, 1976) this type of analysis was employed to evaluate the state of the thoroughness of exploration of the Helez Formation in the southern Hashephela region of Israel. The study area extends between coordinate lines 80 north (roughly, a line connecting Khan Yunis and Ofaqim), 140 north (Ashdod-Gedera-Hulda) and 140 east (Hulda-Mishmar Hanegev);
1997 - The integrated radiation environment at well sites-an adjunct to petroleum exploration
by Past Exploration 1
D. Gill 2 and R. Gabai 2
To what extent have the possibilities been exhausted of discovering concealed subterranean natural resources in a given area? Stated differently, and employing a positive or optimistic viewpoint (the half-empty vs the half-full glass analogy): What are the chances that, in an area which was already tested by some drillholes, a target of a given size has been left undetected? The answer hinges on
two independent sources of information: geological considerations and the level of exploration or the thoroughness of search. By the very nature of exploration ventures, definitive knowledge about the geological favorability of any given point in the explored area is always lacking. To circumvent this inherent difficulty it is constructive to assume, at least as a first step, that if resource targets
exist, their distribution is uniform so that they are equally likely to occur anywhere in the area. Under this simplifying assumption the answer to the above question is a function of the geometry (size, shape, and spatial orientation) of the target being sought and the geographical distribution of past exploratory tests. Each test (e.g., drillhole), whether successful or not, exhausts a certain area
in its immediate geographic neighborhood in the sense that within it, resource targets could not have existed without having been found. The amount and disposition of the exhausted area is a function of the target's geometry, as mentioned above. Each new test reduces the size of the remaining prospective area. The state of areal exhaustiveness of a region (or its prospectiveness-the positive
complement of exhaustiveness) can be evaluated by the mathematical method developed by Singer and Drew (1976). The results obtained are displayed in isopleth contour maps in which the value at each point specifies its degree of exhaustion. For example, a value of 0.5 means that if an elliptical target is centered at this point, 50% of its possible orientation would have been found by
past drill holes. Additional geological considerations can then be brought into account and after proper translation into an inferred geological favorabflity function, these considerations can be integrated with the areal exhaustiveness data
to formulate an optimal search strategy.
Using program RESIN (Singer, 1976) this type of analysis was employed to evaluate the state of the thoroughness of exploration of the Helez Formation in the southern Hashephela region of Israel. The study area extends between coordinate lines 80 north (roughly, a line connecting Khan Yunis and Ofaqim), 140 north (Ashdod-Gedera-Hulda) and 140 east (Hulda-Mishmar Hanegev);
1997 - The integrated radiation environment at well sites-an adjunct to petroleum exploration
Geology Helez formation
The Helez formation underlying the Israel southern coastal plain is composed of alternating shales, sandstones, sandy shales, limestones, and dolomites. 23-24 It reaches depths greater than 1,700 m, is up to 300 m thick, and becomes sandier to the east.
The sandstones constitute about 10% of the formation and are the main oil reservoirs. Most oil is found in the more porous sandstones that were deposited to the east in coastal environment tidal channels or lagoons. Intergranular porosity can reach 20-30% of the rock volume, and permeability reaches 2,000 md.
The pay zones in the Helez formation are 1-12 m thick and are mainly at depths of 1,590 m to more than 1,620 m with a deeper zone at about 1,675-85 m.22 Oil is also found in dolomitic rocks that comprise the upper section of a reef complex. There is smaller production to the west where the formation is more shaly. A marine sandstone facies there has low porosity and contains little oil.
There is no oil in the older Early Cretaceous Gevar'am formation, a thick series of impervious dark to black shales.22 25 The Helez formation is conformable and interfingers with the Gevar'am formation.
Where the Helez formation pinches out in the shales, oil traps have formed (Fig. 2 [28,847 bytes]). The Gevar'am shales are the seals for the traps.25 26 Oil is also found in fractures where Jurassic limestones unconformably underlay the Helez formation.
Helez structure, traps
The oil field is located on a marked Cretaceous to Eocene faulted anticline that coincides with a depositional hinge belt. 25 The structure is tilted with a gentle dip to the east and is downfaulted to the west (Fig. 3 [22,385 bytes]). 22
Folding is related to deep-seated compressional faults. The structure has a N-S Jurassic axial trend in the northern part and a Late Cretaceous-Early Tertiary NE-SW trend in the southern part. Faults in the area have been related to uplifting and tilting at the end of the Jurassic, an Alpine folding phase during Late Cretaceous-Early Tertiary times, and Neogene tensional movement.27
Helez field is a combination stratigraphic-structural trap on the NE-SW trend. Thinning and shoaling of Helez formation sands occurred updip (to the west) leading to the formation of stratigraphic pinchout traps sealed by overlying and interbedded thick shales (Fig. 2). Although the porous sandstones of the Helez formation interfinger with the Gevar'am shales beds in a landward transition zone (to the southeast), they may pinch out before they reach the shales.26 In this case, the sandstones are separated from the shales by a belt of tight oolitic sandy limestone alternating with sandy shale acting as oil trap seals. There is a dolomitic reef complex as well.23
Oil migrated and was trapped during the Neogene after the major tectonic movements. Migration was facilitated by post-folding tensional transverse faults and fractures that cross Helez field ascending from deep layers in the western basin.
On the basis of the close association and interfingering of the Gevar'am black shales with the Helez formation oil bearing sandstones, it was proposed that the shales were the source rocks.23 24 However, data on biomarkers and stable isotopes in the Gevar-am shales and the Jurassic Barnea limestone formation indicated that Barnea formation samples represent both the rock type from which the oil was derived and the migration path.25
Subsequently, transform adjustment faults divided the Helez structure into blocks that separate the Lower Cretaceous pay zones into different reservoirs.22
The Helez formation underlying the Israel southern coastal plain is composed of alternating shales, sandstones, sandy shales, limestones, and dolomites. 23-24 It reaches depths greater than 1,700 m, is up to 300 m thick, and becomes sandier to the east.
The sandstones constitute about 10% of the formation and are the main oil reservoirs. Most oil is found in the more porous sandstones that were deposited to the east in coastal environment tidal channels or lagoons. Intergranular porosity can reach 20-30% of the rock volume, and permeability reaches 2,000 md.
The pay zones in the Helez formation are 1-12 m thick and are mainly at depths of 1,590 m to more than 1,620 m with a deeper zone at about 1,675-85 m.22 Oil is also found in dolomitic rocks that comprise the upper section of a reef complex. There is smaller production to the west where the formation is more shaly. A marine sandstone facies there has low porosity and contains little oil.
There is no oil in the older Early Cretaceous Gevar'am formation, a thick series of impervious dark to black shales.22 25 The Helez formation is conformable and interfingers with the Gevar'am formation.
Where the Helez formation pinches out in the shales, oil traps have formed (Fig. 2 [28,847 bytes]). The Gevar'am shales are the seals for the traps.25 26 Oil is also found in fractures where Jurassic limestones unconformably underlay the Helez formation.
Helez structure, traps
The oil field is located on a marked Cretaceous to Eocene faulted anticline that coincides with a depositional hinge belt. 25 The structure is tilted with a gentle dip to the east and is downfaulted to the west (Fig. 3 [22,385 bytes]). 22
Folding is related to deep-seated compressional faults. The structure has a N-S Jurassic axial trend in the northern part and a Late Cretaceous-Early Tertiary NE-SW trend in the southern part. Faults in the area have been related to uplifting and tilting at the end of the Jurassic, an Alpine folding phase during Late Cretaceous-Early Tertiary times, and Neogene tensional movement.27
Helez field is a combination stratigraphic-structural trap on the NE-SW trend. Thinning and shoaling of Helez formation sands occurred updip (to the west) leading to the formation of stratigraphic pinchout traps sealed by overlying and interbedded thick shales (Fig. 2). Although the porous sandstones of the Helez formation interfinger with the Gevar'am shales beds in a landward transition zone (to the southeast), they may pinch out before they reach the shales.26 In this case, the sandstones are separated from the shales by a belt of tight oolitic sandy limestone alternating with sandy shale acting as oil trap seals. There is a dolomitic reef complex as well.23
Oil migrated and was trapped during the Neogene after the major tectonic movements. Migration was facilitated by post-folding tensional transverse faults and fractures that cross Helez field ascending from deep layers in the western basin.
On the basis of the close association and interfingering of the Gevar'am black shales with the Helez formation oil bearing sandstones, it was proposed that the shales were the source rocks.23 24 However, data on biomarkers and stable isotopes in the Gevar-am shales and the Jurassic Barnea limestone formation indicated that Barnea formation samples represent both the rock type from which the oil was derived and the migration path.25
Subsequently, transform adjustment faults divided the Helez structure into blocks that separate the Lower Cretaceous pay zones into different reservoirs.22