Field Appraisal

Date: 2015-10-07; view: 389.

If an exploratory well shows that hydrocarbons are present, more seismic data is gathered and then a number of appraisal wells are drilled and more data is collected. From th__ __1)data i__2)is poss__ __ __ __3)to esti__ __ __ __4)how mu__ __5)oil a__ __6)gas t__ __7)field cont__ __ __ __8), how diff__ __ __ __ __9)it wi__ __10)be t__11)extract a__ __12)what perce__ __ __ __ __13)of t__ __14)oil a__ __15)gas c__ __16)be extr__ __ __ __ __17). Unfortunately, i__18)'s n__ __19)possible t__20)get ev__ __ __21)last dr__ __22)of o__ __23)out o__24)a reservoir - i__25)the No__ __ __26)Sea, f__ __27)example, oper__ __ __ __ __28)expect t__29)recover ab__ __ __30)40 - 50% of t__ __31)total rese__ __ __ __ __32). This fig__ __ __33)may se__ __34)quite l__ __35), but reme__ __ __ __36)there i__ __37)'t a la__ __38)of o__ __39)and g__ __40). Instead i__41)is tra__ __ __ __42)in t__ __43)pores o__44)the rese__ __ __ __ __45)rock a__ __46)you c__ __47)appreciate th__ __48)it i__ __49)'t poss__ __ __ __50)to g__ __51)every la__ __52)drop o__ __53). Think ba__ __54)to t__ __55)idea th__ __56)oil i__57)held i__58)pores i__59)much t__ __60)same w__ __61)that wa__ __ __62)is he__ __63)in a spo__ __ __64). We kn__ __65)that i__66)isn'__67)possible t__68)get ev__ __ __69)last lit__ __ __70)drop o__71)water o__ __72)of a spo__ __ __73)- it'__74)always a b__ __75)damp. O__ __76)exploration invo__ __ __ __77)lots o__78)people wi__ __79)different ski__ __ __80), for exa__ __ __ __81)geologists, geophy__ __ __ __ __ __ __82), surveyors, mudlo__ __ __ __ __83), computer scien__ __ __ __ __84), marine biolo__ __ __ __ __85), drilling engi__ __ __ __ __86), the dril__ __ __ __87)crew. Alongside these are all the people employed back onshore for example economists, planners, lawyers, IT specialists, environmental advisers and safety advisors to name a few.

4. Miscible methods

One method of enhanced recovery is based on the injection of natural gas either at high enough pressure or containing enough petroleum gases in the vapour phase to make the gas and oil miscible. This met__ __ __1)leaves lit__ __ __2)or n__3)oil beh__ __ __4)the dri__ __ __ __5)gas, b__ __6)the relat__ __ __ __ __7)low visc__ __ __ __ __8)of t__ __9)gas c__ __10)lead t__11)the bypa__ __ __ __ __12)of la__ __ __13)areas o__14)oil, espec__ __ __ __ __15)in reser__ __ __ __ __16)that a__ __17)not homog__ __ __ __ __ __18). Another enha__ __ __ __19)method i__20)intended t__21)recover o__ __22)that i__23)left beh__ __ __24)by a water__ __ __ __ __25)by put__ __ __ __26)a band o__27)soaplike surfa__ __ __ __ __28)material ah__ __ __29)of t__ __30)water. T__ __31)surfactant cre__ __ __ __32)a very l__ __33)surface ten__ __ __ __34)between t__ __35)injected mate__ __ __ __36)and t__ __37)reservoir o__ __38), thus allo__ __ __ __39)the ro__ __40)to b__41)”scrubbed” cl__ __ __42). Often t__ __43)water beh__ __ __44)the surfa__ __ __ __ __45)is ma__ __46)viscous b__47)addition o__48)a polymer i__49)order t__50)prevent t__ __51)water fr__ __52)breaking thr__ __ __ __53)and bypa__ __ __ __ __54)the surfa__ __ __ __ __55). Surfactant floo__ __ __ __56)generally wo__ __ __57)well i__58)noncarbonate ro__ __59), but t__ __60)surfactant mate__ __ __ __61)is expe__ __ __ __ __62)and la__ __ __63)quantities a__ __64)required. O__ __65)method th__ __66)does se__ __67)to wo__ __68)in carb__ __ __ __ __69)rock i__70)the inje__ __ __ __ __71)of car__ __ __72)dioxide, eit__ __ __73)alone o__74)in conju__ __ __ __ __ __75)with nat__ __ __ __76)gas. T__ __77)carbon dio__ __ __ __78)can gre__ __ __ __79)improve reco__ __ __ __80), but ve__ __81)large quant__ __ __ __ __82)at a reaso__ __ __ __ __83)price a__ __84)necessary. Most of the successful projects of this type depend on tapping and transporting (by pipeline) carbon dioxide from underground reservoirs.

5. Thermal methods

There are many reservoirs, usually shallow, that contain oil which is too viscous to produce well. Nevertheless, thr__ __ __ __1)the appli__ __ __ __ __ __2)of he__ __3), economical reco__ __ __ __4)from th__ __ __5)reservoirs i__6)possible. He__ __ __7)crude oi__ __8), which m__ __9)have a visc__ __ __ __ __10)up t__11)one mil__ __ __ __12)times th__ __13)of wa__ __ __14), will sh__ __15)a reduction i__16)viscosity b__17)a factor o__18)10 for ea__ __19)temperature incr__ __ __ __20)of 50° C (90° F). T__ __21)most succe__ __ __ __ __22)way t__23)raise t__ __24)temperature o__25)a reservoir i__26)by t__ __27)injection o__28)steam. I__29)the mo__ __30)widespread met__ __ __31), called st__ __ __32)cycling, a quan__ __ __ __33)of st__ __ __34)is inje__ __ __ __35)through a we__ __36)into a form__ __ __ __ __37)and all__ __ __ __38)time t__39)condense. Conden__ __ __ __ __ __40)in t__ __41)reservoir rele__ __ __ __42)the he__ __43)of vapori__ __ __ __ __ __44)that w__ __45)required t__46)create t__ __47)steam. Th__ __48)the sa__ __49)well i__50)put o__51)production. Af__ __ __52)some wa__ __ __53)production, hea__ __ __54)oil fl__ __ __55)into t__ __56)well bo__ __57)and i__58)lifted t__59)the sur__ __ __ __60). Often t__ __61)cycle c__ __62)be repe__ __ __ __63)several ti__ __ __64)on t__ __65)same we__ __66). A less com__ __ __67)method invo__ __ __ __68)the inje__ __ __ __ __69)of st__ __ __70)from o__ __71)group o__72)wells wh__ __ __73)oil i__74)continuously prod__ __ __ __75)from ot__ __ __76)wells.

A__77)alternate met__ __ __78)for hea__ __ __ __79)a reservoir invo__ __ __ __80)the combu__ __ __ __ __81)of a pa__ __82)of t__ __83)reservoir o__ __84)and i__85)called i__86)situ combu__ __ __ __ __87). Large quant__ __ __ __ __88)of compr__ __ __ __ __89)air mu__ __90)be inje__ __ __ __91)into t__ __92)oil zo__ __93)to sup__ __ __ __94)the combu__ __ __ __ __95). The opt__ __ __ __96)combustion tempe__ __ __ __ __ __97)is 500° C (930° F). T__ __98)hot combu__ __ __ __ __99)products mo__ __100)through t__ __101)reservoir t__102)promote o__ __103)production. In situ combustion has not seen widespread use.

6. The turbodrill

One variation in rotary drilling employs a fluid-powered turbine at the bottom of the borehole to produce the rotary motion of the bit. Known a__1)the turbo__ __ __ __ __2), this instr__ __ __ __ __3)is ab__ __ __4)nine met__ __ __5)long a__ __6)is ma__ __7)up o__8)four ma__ __ __9)parts: t__ __10)upper bea__ __ __ __11), the tur__ __ __ __12), the lo__ __ __13)bearing, a__ __14)the dr__ __ __15)bit. T__ __16)upper bea__ __ __ __17)is atta__ __ __ __18)to t__ __19)drill pi__ __20), which eit__ __ __21)does n__ __22)rotate o__23)rotates a__24)a slow ra__ __25)(6 to 8 revol__ __ __ __ __ __26)per min__ __ __27)). The dr__ __ __28)bit, mean__ __ __ __ __29), rotates a__30)a much fas__ __ __31)rate (500 t__32)1,000 revolutions p__ __33)minute) th__ __34)in conven__ __ __ __ __ __35)rotary dril__ __ __ __36). The po__ __ __37)source f__ __38)the turbo__ __ __ __ __39)is t__ __40)mud pu__ __41), which for__ __ __42)mud thr__ __ __ __43)the dr__ __ __44)pipe t__45)the tur__ __ __ __46). The m__ __47)is dive__ __ __ __48)onto t__ __49)rotors o__50)the tur__ __ __ __51), turning t__ __52)lower bea__ __ __ __53)and t__ __54)drill b__ __55). The m__ __56)then pas__ __ __57)through t__ __58)drill b__ __59)to sc__ __ __60)the ho__ __61)and ca__ __ __62)chips t__63)the sur__ __ __ __64). The turbo__ __ __ __ __65)is cap__ __ __ __66)of ve__ __67)fast dril__ __ __ __68), but t__ __69)bit a__ __70)bearings we__ __71)quickly i__72)the ha__ __ __73)environment. Turbodrills were widely used in the former Soviet republics of Russia and Central Asia, but they are rare elsewhere.