US 12,436,142 B2
Method of preparing degassed oil representative of live oil with equivalent minimum miscible pressure
Shuoshi Wang, Chengdu (CN); Wenhua Zhao, Chengdu (CN); Ping Guo, Chengdu (CN); Zhouhua Wang, Chengdu (CN); Jianfen Du, Chengdu (CN); Yisheng Hu, Chengdu (CN); and Huang Liu, Chengdu (CN)
Assigned to Southwest Petroleum University, Chengdu (CN)
Filed by Southwest Petroleum University, Chengdu (CN)
Filed on Apr. 5, 2023, as Appl. No. 18/130,924.
Claims priority of application No. 202210508931.7 (CN), filed on May 10, 2022.
Prior Publication US 2023/0366869 A1, Nov. 16, 2023
Int. Cl. G01N 33/28 (2006.01)
CPC G01N 33/28 (2013.01) 3 Claims
OG exemplary drawing
 
1. A preparation method of a representative degassed oil with an equivalent minimum miscible pressure, comprising the following steps in turn:
(1) measuring minimum miscible pressures of a live oil and a degassed oil corresponding to the live oil as MMP1 and MMP2 respectively, wherein a relationship between a minimum miscible pressure (MMP) and an average carbon number Cn, and a relationship between the average carbon number Cn and an equivalent carbon number EACN are expressed as follows:
MMP=0.203Cn+4.543  (1)
EACN=h×Cn  (2)
wherein h is an empirical coefficient, assuming that his 1, average carbon numbers of the live oil and the degassed oil are calculated to be Cn1 and Cn2 respectively, and equivalent carbon numbers of the live oil and the degassed oil are EACN1 and EACN2 respectively;
(2) allowing the equivalent carbon number EACN and a salinity S* to satisfy the following formula:
ln(S*)=K×EACN−Cc  (4)
wherein K and Cc are characteristic parameters of a surfactant, and substituting EACN1 and EACN2 into Formula (4), salinities of the live oil and the degassed oil are calculated to be S1* and S2* respectively;
(3) scanning a salinity of a degassed oil microemulsion system, wherein a measured salinity of the degassed oil is measured to be S2*′, wherein according to Formula (4), an equivalent carbon number EACN2′ of the degassed oil after a correction is obtained, and a value of the empirical coefficient h is calculated according to Formula (2) to obtain an equivalent carbon number EACN1′ of the live oil after the correction;
(4) calculating an amount of liquid hydrocarbons required to be added to reduce the equivalent carbon number EACN2′ of the degassed oil to the equivalent carbon number EACN1′ through a linear mixing as follows:
[n1/(n1+n2)]×EACN2′+[n2/(n1+n2)]×EACNhydrocarbon=EACN1′  (5)
wherein n1 is an amount of substance corresponding to the degassed oil, n2 is an amount of substance corresponding to the liquid hydrocarbons required to be added, EACNhydrocarbon is an effective carbon number of a hydrocarbon, and the amount of the liquid hydrocarbons required to be added is calculated according to Formula (5);
(5) adding a calculated amount of the liquid hydrocarbons into the degassed oil and stirring the liquid hydrocarbons and the degassed oil until the liquid hydrocarbons and the degassed oil are fully mixed to obtain a compound degassed oil, wherein a salinity S2*″ of the compound degassed oil added with the liquid hydrocarbons is measured again by a salinity scanning, and EACN2″ according to the salinity S2*″ of the compound degassed oil is calculated by Formula (4);
(6) when the EACN2″ of the compound degassed oil is consistent with the equivalent carbon number EACN1′ of the live oil, obtaining the representative degassed oil with the equivalent minimum miscible pressure;
when the EACN2″ of the compound degassed oil is greater than the equivalent carbon number EACN1′ of the live oil, adding the liquid hydrocarbons for an adjustment with a step length of 1% of a degassed oil volume until the representative degassed oil with the equivalent minimum miscible pressure is obtained; and
when the EACN2″ of the compound degassed oil is smaller than the equivalent carbon number EACN1′ of the live oil, adding the degassed oil for the adjustment with the step length of 1% of the degassed oil volume until the representative degassed oil with the equivalent minimum miscible pressure is obtained.