Patent ID: 11920468
Assignee: CONOCOPHILLIPS COMPANY
Field: Civil engineering (Other fields)
Classification: CPC E | IPC E

Claim 9:
10. A method of monitoring produced water production, said method comprising:
a) deploying a tool downhole in a hydrocarbon well in a formation, said tool comprising ion sensitive sensors comprising a calcium sensitive sensor, a sodium sensitive sensor and a chloride sensitive sensor, plus a temperature sensor, plus a flow rate sensor; and
b) drawing said tool upwell and continuously measuring the following:
i) a concentration of at least calcium, sodium, and chloride ions;
ii) a temperature;
iii) a rate of flow;

c) determining inflow positions along said well by a change in temperature and/or rate of flow;
d) obtaining Na+/Cl− and Ca2+/Cl− ratios at each said inflow positions;
e) comparing obtained Na+/Cl− and Ca2+/Cl− ratios and known Na+/Cl− and Ca2+/Cl− from one or more of i) natural formation water from said formation, ii) water injected into said formation, and iii) seawater above said formation (if said well is an offshore well);
f) determining a contribution of one or more of i), ii) and iii) to produced water based on said comparison at said inflow positions.