Qual­i­ta­tive assess­ment of oil and gas prospec­tiv­i­ty of a sub­soil area is a комплекс of stud­ies aimed at inte­grat­ing geo­log­i­cal data in order to iden­ti­fy ter­ri­to­ries favor­able for hydro­car­bon accu­mu­la­tion, clas­si­fy them, dif­fer­en­ti­ate them by degree of prospec­tiv­i­ty, and deter­mine opti­mal direc­tions for fur­ther explo­ration activ­i­ties.

A qual­i­ta­tive oil and gas prospec­tiv­i­ty assess­ment is car­ried out through com­pre­hen­sive analy­sis of estab­lished petro­le­um sys­tem cri­te­ria for the stud­ied объект, eval­u­a­tion of their spa­tial vari­abil­i­ty and dis­tri­b­u­tion pat­terns of hydro­car­bon accu­mu­la­tions, as well as inter­pre­ta­tion of geo­log­i­cal, geo­phys­i­cal, geo­chem­i­cal, hydro­ge­o­log­i­cal, ther­mo­bar­ic and oth­er region­al data. Poten­tial petro­le­um-bear­ing com­plex­es are iden­ti­fied, tec­ton­ic analy­sis is per­formed, and petro­le­um-geo­log­i­cal zon­ing of the ter­ri­to­ry is con­duct­ed. The final stage includes prepa­ra­tion of prospec­tiv­i­ty maps for region­al-scale fore­cast objects and graph­i­cal mod­els (cross-sec­tions and struc­tur­al maps) for local prospects, along with rec­om­men­da­tions for fur­ther explo­ration with­in spe­cif­ic areas.

Region­al fore­cast – assess­ment of oil and gas prospec­tiv­i­ty of a large part of a sed­i­men­ta­ry basin aimed at iden­ti­fy­ing region­al-scale fore­cast objects, dif­fer­en­ti­at­ing them by degree of prospec­tiv­i­ty, and con­duct­ing petro­le­um-geo­log­i­cal zon­ing.

Dur­ing region­al fore­cast­ing, the main fea­tures of the geo­log­i­cal struc­ture and stages of geo­t­ec­ton­ic devel­op­ment are stud­ied, includ­ing lithos­trati­graph­ic char­ac­ter­is­tics, hydro­ge­o­log­i­cal and geo­chem­i­cal con­di­tions. Petro­le­um-bear­ing com­plex­es (nat­ur­al reser­voirs) and poten­tial hydro­car­bon accu­mu­la­tion zones are iden­ti­fied, quan­ti­ta­tive esti­ma­tion of fore­cast resources in cat­e­gories D1 and D2 is per­formed, dis­cov­ered and pre­dict­ed hydro­car­bon zones are out­lined, and rec­om­men­da­tions are devel­oped regard­ing the selec­tion of objects for zon­al fore­cast­ing.

Local fore­cast – assess­ment of oil and gas prospec­tiv­i­ty based on a комплекс of geo­log­i­cal indi­ca­tors of a local­ized object (an anti­cli­nal struc­ture of the third order or var­i­ous types of non-anti­cli­nal traps) with­in a spe­cif­ic strati­graph­ic inter­val rep­re­sent­ing an отдельный oil and gas reser­voir. It is close­ly relat­ed to zon­al fore­cast­ing and is con­duct­ed sub­se­quent­ly. The dif­fer­ence between them lies in the scale of geo­log­i­cal bod­ies con­sid­ered and the set of geo­log­i­cal cri­te­ria ana­lyzed.

• Geo­log­i­cal study. Col­lec­tion and analy­sis of his­tor­i­cal geo­log­i­cal data, geo­log­i­cal map­ping, struc­tur­al inter­pre­ta­tion, and seis­mic sur­veys to deter­mine the main char­ac­ter­is­tics of the geo­log­i­cal struc­ture and iden­ti­fy poten­tial reser­voir traps.
• Well drilling. Drilling of explo­ration wells to obtain direct evi­dence of hydro­car­bon pres­ence. Lithol­o­gy, hydro­car­bon shows, dis­solved gas­es, and reser­voir prop­er­ties con­firm petro­le­um poten­tial.
• Geo­chem­i­cal analy­sis. Lab­o­ra­to­ry analy­sis of rock and flu­id sam­ples to iden­ti­fy geo­chem­i­cal indi­ca­tors of hydro­car­bon gen­er­a­tion and migra­tion. Mol­e­c­u­lar and com­po­si­tion­al analy­sis of hydro­car­bons pro­vides crit­i­cal infor­ma­tion about petro­le­um poten­tial.
• Geo­phys­i­cal sur­veys. Appli­ca­tion of seis­mic, elec­tri­cal, mag­net­ic, and grav­i­ty meth­ods to obtain addi­tion­al data on sub­sur­face struc­ture. These meth­ods help iden­ti­fy poten­tial traps and assess the size and char­ac­ter­is­tics of prospec­tive reser­voirs.
• Eco­nom­ic eval­u­a­tion. Assess­ment of poten­tial rev­enues from hydro­car­bon pro­duc­tion and esti­ma­tion of devel­op­ment and oper­a­tional costs to deter­mine com­mer­cial via­bil­i­ty.
• Reser­voir mod­el­ing. Con­struc­tion of geo­log­i­cal and reser­voir mod­els reflect­ing struc­tur­al con­fig­u­ra­tion, reser­voir dis­tri­b­u­tion, and flu­id flow dynam­ics to fore­cast hydro­car­bon behav­ior and opti­mize devel­op­ment strate­gies.
• Risk assess­ment. Eval­u­a­tion of geo­log­i­cal, tech­ni­cal, envi­ron­men­tal, and finan­cial risks asso­ci­at­ed with explo­ration and devel­op­ment, along with devel­op­ment of mit­i­ga­tion strate­gies.
• Report­ing. Prepa­ra­tion of a com­pre­hen­sive report con­tain­ing geo­log­i­cal, geo­phys­i­cal, and eco­nom­ic analy­ses. This doc­u­ment serves as a basis for invest­ment deci­sions and licens­ing pro­ce­dures.

It should be not­ed that oil and gas prospec­tiv­i­ty assess­ment is a com­plex and mul­ti-stage process requir­ing inte­gra­tion of geo­log­i­cal, geo­phys­i­cal, geo­chem­i­cal, and eco­nom­ic data. It enables eval­u­a­tion of hydro­car­bon pro­duc­tion poten­tial and assess­ment of devel­op­ment effi­cien­cy and prof­itabil­i­ty. This tech­ni­cal process depends on numer­ous fac­tors and requires high­ly qual­i­fied geol­o­gists, engi­neers, and petro­le­um indus­try spe­cial­ists.