EXHIBIT 21

SUBSIDIARIES OF UNOCAL CORPORATION

NAME OF COMPANY (a) ORGANIZED UNDER LAW OF
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Union Oil Company of California, dba "UNOCAL" California
Molycorp, Inc. Delaware
Philippine Geothermal, Inc. California
Pure Resources, Inc. Delaware
Titan Exploration, Inc. Delaware
Pure GP, LLC Delaware
Pure Resources I, Inc. Deleware
Pure Resources Holdings, Inc. Nevada
Pure Resources, L.P. (b) Texas
44 Canyon, LLC Colorado
PK I, L.P. (c) Delaware
Pure Partners, L.P. (d) Delaware
PK II, L.P. (c) Delaware
PK III, L.P. (c) Delaware
Pure Resources Holdings, LLC Nevada
HEP Pure, LP (e) Delaware
HEP Partners, LP (f) Delaware
La Plata Associates, LLC Colorado
HEP Pure Acquisition, LLC Delaware
Spirit Energy Management, L.L.C. Delaware
Spirit Energy 76 Development, L.P. (g) Delaware
Spirit Energy 76 Investment, L.L.C. Delaware
Unocal Foreign Investments Inc. Delaware
Unocal Geothermal of Indonesia, Ltd. Bermuda
Unocal International Corporation Nevada
Unocal Bangladesh Block Twelve, Ltd. (h) Bermuda
Unocal Bangladesh Exploration, Ltd. (i) Bermuda
Unocal Canada Limited Alberta
Cal Ven Limited Alberta
Northrock Resources Ltd. (j) Alberta
Northrock Energy Ltd. Alberta
Northrock Resources (k) Alberta
Paragon Petroleum Corporation Alberta
Unocal Canada Alberta Hub Limited Alberta
Unocal Canada International Company Nova Scotia
Unocal Ganal, Ltd. (l) Bermuda
Unocal Global Ventures, Ltd. (m) Bermuda
Unocal Bangladesh Blocks Thirteen and Fourteen, Ltd. Bermuda
Unocal Bangladesh, Ltd. Bermuda
Unocal Myanmar Offshore Co., Ltd. Bermuda
Unocal Asia-Pacific Ventures, Ltd. Bermuda
Unocal Khazar Holdings, Ltd. Bermuda
Unocal Khazar, Ltd. (n) Bermuda
Unocal Makassar, Ltd. Bermuda
Unocal Indonesia, Ltd. Bermuda
Unocal Indonesia Company (o) Bermuda
Unocal Netherlands B.V. Netherlands
Unocal Rapak, Ltd. (p) Bermuda
Unocal Thailand, Ltd. (q) Bermuda
Unocal Pipeline Company California
Unocal Capital Trust Delaware
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(Footnotes on following page.)

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(a) The indented companies are subsidiaries of Union Oil Company of California.
Except as indicated, each entity is owned 100 percent by the entity under
which it is indented. The names of approximately 282 subsidiaries are
omitted inasmuch as such subsidiaries, considered in the aggregate as a
single subsidiary, would not constitute a significant subsidiary.

(b) Owned 99 percent by Pure Resources Holdings, Inc. and one percent by Pure
Resources I, Inc.

(d) Owned 39 percent by PK I, L.P., 7 percent by PK III, L.P., 3 percent by PK
II, L.P., and 1 percent by Pure Resources I, Inc.

(e) Owned 99 percent by Pure Resources Holdings, LLC and one percent by Pure
GP, LLC.

(f) Owned 1 percent by HEP Pure, LP and 99 percent by HEP Pure Acquisition,
LLC.

(g) 100 percent of the general partnership interest (approximately 55 percent
of the initial capital) is owned by Spirit Energy Management, L.L.C.

(h) Owned 95 percent by Unocal International Corporation and 5 percent by
Unocal Foreign Investments Inc.

(i) Owned 96.62 percent by Unocal International Corporation and 3.38 percent by
Unocal Foreign Investments Inc.

(j) 100 percent of the Class A Preferred Shares and Class A Common Shares is
owned by Unocal Canada Limited, and the Class B Common Shares is owned 95.6
percent by Unocal Canada Limited, 3.10 percent by Unocal Canada Alberta Hub
Limited and 1.3 percent by Cal Ven Limited.

(k) A general partnership owned 69.24 percent by Northrock Resources Ltd.,
13.07 percent by Paragon Petroleum Corporation, and 4.04 percent by
Northrock Energy Ltd.

(l) Owned 94.49 percent by Unocal International Corporation and 5.51 percent by
Unocal Foreign Investments Inc.

(m) Owned 88.89 percent by Unocal International Corporation and 11.11 percent
by Unocal Foreign Investments Inc.

(n) Owned 65 percent by Unocal Khazar Holdings, Ltd., and 35 percent by Unocal
Global Ventures, Ltd.

(o) A general partnership owned 53.13 percent by Unocal Indonesia, Ltd., and
46.87 percent by Unocal Canada International Company.

(p) Owned 95 percent by Unocal International Corporation and 5 percent by
Unocal Foreign Investments Inc.

(q) Owned 81.80 percent by Unocal International Corporation and 18.20 percent
by Unocal Canada International Corporation.

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