Study on thermal evolution of organic matter simulation of the four basins in the eastern of Songliao Basin

Transcription

1 Study on thermal evoluton of organc matter smulaton of the four basns n the eastern of Songlao Basn Cunxao Cu 1, a, Yuanln Meng 1, b, Xngu Zhou 2, c, Dandan Wang 2, d, Ge Jang 3, e, Zhen Luo 3, f 1 Northeast Petroleum Unversty, Daqng, , Chna 2 Strategc research center of ol & gas resources, Mnstry of Land and Resources, Bejng, Chna 3 No.2 Ol Producton Company, Daqng olfeld, Daqng, , Chna a c119815@163.com, b qhdmyl@163.com, c xnguzhou100@sna.com, d ddwangcn@163.com, e @qq.com, f @qq.com Abstract In order to determne the tme of hydrocarbon generaton and expulson n the four typcal supermposed basns n the eastern of Songlao Basn n Chna, fgure out the hydrocarbon expulson threshold and the correspondng Ro value, organc matter abundance and type accordng to correspondng geochemstry data and hydrocarbon expulson threshold theory, combned wth the basn smulaton technology, restore the thermal evoluton of organc matter. The followng conclusons are obtaned. The hydrocarbon source rocks n the lower Cretaceous formatons manly began to hydrocarbon generaton at the early-mddle of Early Cretaceous, and hydrocarbon expulson at the end Early Cretaceous, the part of the hydrocarbon source rocks generate and expelled hydrocarbon after the Palaeogene. Keywords the eastern of Songlao Basn, thermal evoluton of organc matter, the tme of hydrocarbon generaton and expulson, basn smulaton technology 1. Introducton Eastern basn of Songlao Basn s refers to the basns n the east of the YShu fracture, whch are manly supermposed basns. These basns have had low exploraton degree, but research shows that they have larger exploraton potental accordng to the present exploraton result. In the study of hydrocarbon accumulaton perods and genetc types of ol and gas, the most crtcal s the study of the hstory of hydrocarbon expulson n hydrocarbon source rock. Predecessors carred out prelmnary dscusson for ol and gas accumulaton n the eastern basns, but the study of hydrocarbon expulson perod manly only used the results of the study of hydrocarbon generaton characterstcs. The author attempts to apply the basn smulaton technology, restore the thermal evoluton of organc matter, concludng the tme of hydrocarbon generaton and expulson n the four typcal supermposed basns n the eastern basn group, n order to the eastern basn group of ol and gas accumulaton research and exploraton deployment provde theoretcal bass and practcal gudance. 2. Formaton and hydrocarbon source rock characterstcs All the basn basement s palaeozoc era, former palaeozoc group metamorphc basement, part assocated wth each phase of the grante. The sedmentary cover s the Cenozoc and Mesozoc strata. 90

2 Sanjang Basn, Jx Basn and Bol Basn have manly the Mesozoc strata, but Huln Basn have the Cenozoc and Mesozoc strata. n ths researchng area[1]. Sanjang Basn develops Ddao(K1dd), Chengzhe(K1ch), Mulng (K1m) and Dongshan(K1d) formaton n Mesozoc. Hydrocarbon source rocks are manly located n the K1ch and K1m formatons.the formatons feature s the same as Sangjang Basn n Jx Basn and hydrocarbon source rocks are manly located n the K1ch and K1m formatons. Bol basn manly develops Xayunshan(K1x), Shangyunshan(K1s), Zhushangzu(K1z), Dongshan(K1d), Houshgou(K2h) and Halang(K2hl), and hydrocarbon source rocks are manly located n the K1x and K1s formatons.huln Basn s dfferent from the above three basn, whose man exploraton formaton s n Cenozoc and whch have Huln(Eh), Fujn(Nf) and Daotaqao(Nd) formatons n Cenozoc. Hydrocarbon source rocks are manly located n the Eh formatons. Thermal evoluton of organc matter smulaton need combne wth hydrocarbon source rocks characterstc. We fgure out the hydrocarbon expulson threshold and the correspondng Ro value, organc matter abundance and type accordng to correspondng geochemstry data and hydrocarbon expulson threshold theory [2] (table1). Basn Table 1 the four basns hydrocarbon source rocks characterstc The formatons of Hydrocarbon Hydrocarbon Organc hydrocarbon expulson expulson Ro matter source rocks threshold (m) (%) abundance Organc matter type Sanjang K1ch,K1m medum II2 Bol K1x,K1s poor III Huln Eh good I Jx K1ch,K1m good II1 3. Thermal evoluton of organc matter smulaton. 3.1 Thermal evoluton of organc matter smulaton model Before the recovery of thermal evoluton of organc matter, we should restore geologc hstory and thermal hstory. The geologc hstory and thermal hstory smulaton parameters are tme of formaton, thckness, lthology, mneral composton, denudaton amount, ancent land surface temperature, water depth, rock thermal conductvty etc. Under the premse of n the hstory of thermal recovery, the author used Easy% Ro method to restore the thermal evoluton of organc matter. Easy % Ro method s generally consdered the most accurate method for predcton of Ro, whch s has been wdely used n the word [3-5]. It s establshed accordng to the nature of the chemcal knetcs whch vtrnte generated n the process of the evoluton of H2O, CO2, CH4 and other hydrocarbons, and a seres of parallel reacton actvaton energy of the 20 causes the varaton of vtrnte of elements and the correspondng growth of vtrnte reflectance. Easy % Ro model s sutable for the large change range of temperature and heatng rate, whch can more precsely calculate the medum or hgh heat evoluton degree; ths chemcal reacton can use chemcal knetcs model descrbed by the Arrhenus chemcal equaton: dw / dt W Aexp( E / RT ), (1) W / Wo exp Aexp( E / ) 0 RT dt 91, (2) Where W s the unreacted concentraton for component, E s an catvaton energy for component, Wo s the ntal concentraton for component,a s a frequency or pre-exponental, R s the unversal gas constant, T s temperature, t s tme. The fracton of reactant converted s

3 20 1 / o, (3) F f W W Where f are stochometrc, or weghtng, coeffcents for the parallel reacton. The relatonshp between F and Ro can be expressed as: 1 Ro exp F j j=1,2,3,,n (4) Fj s the fracton of reactant converted (vtrnte converson)n chemcal knetcs n the jth bured pont of boundary of formaton n well, whch values range from 0 to 0.85 and the correspondng Ro value of 0.2% ~ 4.7%, so Easy% Ro model s obvously sutable for most of the ol and gas sedmentary basn. We can use ths model to restore the hstory of the organc matter maturty n the study area and t can verfy rectfy result by usng the measured vtrnte reflectance (Ro). 3.2 smulaton results Applcaton of basn smulaton technology, on the bass of the bural hstory and geothermal hstory of recovery, we can recover organc matter thermal evoluton hstory. The parameters needed n basn mod have tme of formaton, thckness, lthology, mneral composton, denudaton amount, ancent land surface temperature, water depth, rock thermal conductvty, etc., whch are taken from our research data and the predecessors' research results [1]. Take Sanjang basn, for nstance. Through sngle-well smulaton of the BC1 well (Fg.1), we concluded,n 125Ma, vtrnte reflectance of the hydrocarbon source rocks reached 0.5% n K1ch formaton, t began to hydrocarbon generaton. The basn uplfted at the end of the Early Cretaceous (K1) because of tectonc movement. Then, basn began to declne, the Dongshan formaton s rapdly deposted. At the same tme, the vtrnte reflectance of the hydrocarbon source rocks reached 0.5% n K1m formaton, t began to hydrocarbon generaton. In 113Ma, vtrnte reflectance of the hydrocarbon source rocks reached 0.7% n K1ch formaton, t began to hydrocarbon expulson Then Sanjang basn uplfted agan, ground temperature s reduced, and the surroundng have no effect on organc matter thermal evoluton of the geologcal factors, such as thermal flud actvty. Therefore, the thermal evoluton of organc matter rate slows, vtrnte reflectance of the hydrocarbon source rocks reached 0.7% n K1m formaton at the late of the Late Paleogene (E), t began to hydrocarbon expulson. The maturated the source rocks wth hgh organc matter abundance K1ch formaton n begn to generate a great deal of hydrocarbons the late cretaceous (K2). Fg.1. Organc matter thermal evoluton hstory of BC1 well n Sanjang basn Applcaton of basn smulaton technology, we t recovered thermal evoluton of organc matter n the other three basn. As shown n Fgure4-7 and Table 2, smlar to Sanjang basn, Jx basn has 92

4 experenced smlar tectonc evoluton process, the hydrocarbon source rocks n K1ch formaton began to hydrocarbon generaton n 130Ma(K1ch) and hydrocarbon expulson n 120Ma(K1d). The hydrocarbon source rocks n K1m formaton began to hydrocarbon generaton at the late Early Cretaceous and hydrocarbon expulson at the early of the Palaeogene. The hydrocarbon source rocks are manly dstrbuted n Paleogene Huln formaton(eh) n Huln basn, whch began to hydrocarbon expulson n 29Ma(Eh). Bol basn of the lower cretaceous hydrocarbon source rock manly began to hydrocarbon generaton n 134Ma(K1s) and hydrocarbon expulson at the mddle-late Early Cretaceous. The source rocks n the Shangyunshan formaton reached hydrocarbon generaton n 130Ma(K1z) and hydrocarbon expulson n 102.7Ma(K1d). Table 2 The tme of hydrocarbon expulson n fve basns Basn Sanjang Bol Huln Jx The tme of hydrocarbon generaton (Ma) The tme of hydrocarbon expulson(ma) Fg.2. Organc matter thermal evoluton hstory of H2 well n Huln basn Fg.3. Organc matter thermal evoluton hstory of BC2 well n Bol basn Fg.4. Organc matter thermal evoluton hstory of JC1 well n Jx basn 93

5 4. Concluson The hydrocarbon source rocks n the lower Cretaceous formatons manly began to hydrocarbon generaton at the early-mddle of Early Cretaceous, and hydrocarbon expulson at the end Early Cretaceous, the part of the hydrocarbon source rocks generate and expelled hydrocarbon after the Palaeogene. Acknowledgment Ths work s supported by the Natonal Natural Scence Foundaton of Chna (U and ),Strategc research center of ol & gas resources,mnstry of Land and Resources ( ), Scence Foundaton of Helongjang (QC ) and Scence Foundaton of Northeast Petroleum Unversty(NEPUQN ). References [1] Meng Qnglong. "Study on Basn Numercal Smulaton and It s Geologcal Sgnfcance n the Eastern Perpheral Basns of the Daqng Exploraton Area." Changchun: Jln Unversty, [2] Pang Xongq. Theory of expulson threshold controllng ol dstrbuton and ts applcaton. Ptroleum Industry Press, Bejng, [3] Sweeney, Jerry J., Alan K. Burnham. "Evaluaton of a smple model of vtrnte reflectance based on chemcal knetcs (1)." AAPG Bulletn (1990): [4] Burnham, Alan K., Jerry J. Sweeney. "A chemcal knetc model of vtrnte maturaton and reflectance." Geochmca et Cosmochmca Acta (1989): [5] Lttke, R., Büker, C., Lückge, A., Sachsenhofer, R. F., Welte, D. H. "A new evaluaton of palaeoheat flows and eroded thcknesses for the Carbonferous Ruhr basn, western Germany." Internatonal Journal of Coal Geology 26.3 (1994):