These 27 consolidated appeals are from separate judgments entered in declaratory judgment actions brought by lessors or their successors to determine whether the oil and gas leases involved had terminated as to all horizons below sea level at the expiration of their respective primary terms because of failure to obtain production. They present a common question of law bearing on similar and! undisputed facts. Tjventy-four of the actions were removed from Kansas state courts and three were filed originally in federal court. There is unquestioned diversity jurisdiction. The parties, agreeing that there were no factual issues, each moved for summary judgment and' the lower court held that the leases had all been continued beyond their primary terms by gas production secured within those terms from horizons above sea level. The lessors have appealed.
The 27 leases cover land in the Hugoton Field, Seward County, Kansas, and were identical in form, differing only as to date, lessor or lessors, and land descriptions. Twenty-four were executed! during 1941 and 1942 and three in 1944. Each was for a 10-year primary term. By mesne assignments Plains Natural Gas Company (Plains) became the owner of the leases as to all horizons above sea level and appellee-defendant Westhoma Oil Company (Westhoma) became the owner of the leases as to all horizons below sea level. No question is raised as to the validity of these assignments on the basis of horizontal divisions.
The Kansas Corporation Commission by proration order established 640 acres as the basis for computing allowables in the Hugoton Field.1 In an appropriate manner, Plains acted to consolidate its holdings into 640-acre units. The statement accomplishing this purpose provided that:
“[A] 11 producing horizons which are situated above and down to, but not below, the sea level, shall be deemed, treated and operated as a consolidated gas leasehold estate.”
*729Within the primary term of each lease Plains secured commercial gas production from above-sea-level horizons on each of the consolidated units. As to 9 of the leases the producing well is on the leased land and as to 18 the well is located elsewhere on the unit involved. No production of oil or gas was obtained during the primary term from below-sea-level horizons.
Each lease contained a “thereafter” clause which will be discussed later. Ordinarily an oil and gas lease is extended beyond the primary term by a “thereafter” clause if a producing well is obtained at any location on the leased premises during the primary term.2 None of the parties question the general rule that production from any part of a consolidated or pooled unit perpetuates all leases within the unit, even as to ununitized acreage, unless the leases provide to the contrary.3 Each lease in question also contains what is called a “Pugh clause” 4 which is designed to prohibit lease continuation beyond the primary term as to nonproducing areas not included within a productive unit.
The habendum clauses of the leases provide a term of 10 years and as long thereafter as oil or gas is produced from the premises “and as long as hereinafter otherwise provided in the event of consolidation.”5 The parties agree that the occurrence of production on or off the leased premises included within a unit makes no difference in the disposition of the controversy and that the “hereinafter otherwise provided” clause controls because there was consolidation. In these circumstances, this court is not concerned with what the situation might be in the absence of such an agreement.
The Kansas Supreme Court has established rules which govern the construction and application of oil and gas leases in that state. In Tate v. Stanolind Oil & Gas Co., 172 Kan. 351, 240 P.2d 465, 468-469, it is said that the intent of the parties is the primary question ; that reasonable rather than unreasonable interpretations are favored; that meaning 'should be ascertained by consideration of all pertinent provisions rather than “by a critical analysis of a single or isolated provision”; that in the event of ambiguity or uncertainty consideration must be given to “the instrument as a whole, the object sought to be obtained, and other circumstances, if any, which tend to clarify the real purpose and intent of the parties”; and that a practical and equitable construction must be given to ambiguous terms. We must decide the cases on the basis of the instruments before us and the Kansas law.
The trial court held that the Pugh clauses were written in “surface sounding terms” and do not “specifically or clearly designate underground horizons” and concluded that the provisions of the Pugh clauses terminating the leases at the end of the primary terms as to ununitized nonproducing portions apply only to “partial unitization of less than all of the surface acreage covered by the leases.” As all the surface acreage was unitized,' and as there was production from each unit, the decision was that the leases were continued beyond the primary terms as to all horizons.
Admittedly, the Pugh clauses apply to vertical divisions of the leased premises. *730The query is whether they apply to horizontal divisions. In determining the issue we are aided by no decisions which are directly in point. Broussard v. Phillips Petroleum Company, supra, and Humble Oil & Refining Co. v. Hutchins, 217 Miss. 636, 64 So.2d 733, 65 So.2d 824, relied on by lessors, are not helpful as each concerned the application of a Pugh clause to a vertical rather than a horizontal division. Westhoma relies on Martin v. Texas Gulf Producing Co., 223 Miss. 872, 79 So.2d 270, involving a lease which did not contain a Pugh clause. The court there rejected the contention that -failure to drill below a horizon which had been unitized and from which production had been obtained off the leased premises but within the unit terminated the lease. White v. Frank B. Treat & Son, 230 La. 1017, 89 So.2d 883, also cited by Westhoma, was concerned with a mineral servitude rather than a lease and held that production from a unitized zone continued the servitude as to all zones. No Kansas decisions bearing on the specific point have been brought to our attention.
Under the Pugh clauses the lessee is authorized to consolidate the leasehold estate, “or any part or parts thereof,” with the mineral leasehold estate, “or parts thereof,” in other lands upon which the lessee at the time has a valid lease. The consolidation is limited to include not more than 2,560 acres. The lengthy and technical arguments as to whether the word “part” is confined to vertical divisions on the basis of surface acreage or also encompasses horizontal divisions on the basis of depth can be simply resolved. The ordinary practice is to confine consolidations to a formation or pool which constitutes a known common source of supply.6 In situations where there is more than one source or pool underlying the same land 7 a comprehensive consolidation from the surface to the center of the earth carries with it the potential of grievous complications if different geographical units are established for different producing formations.8 The leases contain no prohibition against the recognized practice of consolidating in terms of sources of supply, pools, or depth. The parties recognize the validity of the partial assignments to Plains and Westhoma with division on the basis of depth. Plains could not consolidate the entire leasehold estate as it did not own that portion below sea level. In the situations presented it is our opinion that “part” as used in the consolidation authorization includes both horizontal and vertical divisions.
The Pugh clause lease continuation provisions are found in subparagraph 9 (a) which reads that in the event of consolidation the lease shall be continued “as to the premises covered hereby and included in any such consolidation of estates” by a producing gas well located on a consolidated unit or by oil production from a well on leased land.
Lease termination is covered by sub-paragraph 9(b) of the Pugh clause which states that the lease terminates at the expiration of the primary term as to any “tract or tracts not included in a consolidation held in force by production” unless there is production in accordance with other lease terms.
Consistency between 9(a) and 9(b) requires that “premises” as appearing in 9(a) and “tract or tracts” as appearing in 9(b) be given the same meaning. We deem it unnecessary to engage in a semantic analysis of the technical implications of the quoted terms. Definitions can be found which confine those terms *731to surface application and other definitions give them such generality of meaning as to include both surface and subsurface rights. It is enough that consolidation may be on.the basis of horizontal as well as vertical divisions and the consolidation here made includes only that portion of the leasehold estate which is above sea level. The portion below sea level was not consolidated and hence is not within the purview of 9(a) and the continuation provisions of that sub-paragraph do not apply. By the same reasoning the termination provisions of 9(b) are applicable and terminate the leases as to the below-sea-level horizons at the end of the primary term because there was no production therefrom during that term.
To avoid this conclusion Westhoma argues that the lease provisions for delay rentals and minimum gas royalties are stated in terms of surface acres, that the lease must be considered in its entirety, and that the inapplicability of the delay rental and minimum gas royalty provisions to horizontal divisions requires the conclusion that consolidations must likewise be treated solely from the standpoint of surface acres. As we are not concerned with delay rentals or royalties, the provisions in regard thereto are pertinent only so far as they bear on intent and for such purpose we find them without persuasive effect. Delay rentals are specifically mentioned in 9(b) and, as has been shown, that subparagraph ends the leases at the expiration of the primary term as to unconsolidated unproductive tracts. Provision for rental on an acreage basis does not mean that the parties intended lease continuation for that part of the leasehold estate which was without a consolidation and which was unproductive.
Problems relating to minimum royalties payable on an acreage basis obviously can cause complications in the event there is production from more than one horizon but those complications will occur regardless of whether the lease is divided on a horizontal basis. Granting that in hypothetical situations difficulty might arise over the rent and royalty provisions, the fact remains that bothersome lease provisions of uncertain meaning and application are of little help in determining the meaning of other lease provisions.
Westhoma emphasizes the indivisibility of the express and implied covenants of a single oil and gas lease.9 The liabilities of lessee and his assignee are not altered by any division which the lessee may make of his interests,10 but that rule has no effect here. The separation of the lease into two parts with the lease continuing as to the upper horizons and terminating as to the lower horizons results from the application of lease terms. There is nothing to prevent parties from agreeing that a lease may be separated under certain conditions. The argument that the conclusion reached imposes additional requirements to keep the lease alive is unimpressive. Under the Pugh clauses if there were vertical consolidations of less than all lease acreage, there would be the additional requirement of drilling and obtaining a producing well on the unconsolidated area. The fact that the result also ensues from a horizontal consolidation does not make the Pugh clauses any less effective when there is a horizontal rather than a vertical consolidation. The same requirements apply to each.
We must arrive at the intent of the parties. The Pugh clauses are for the protection of the lessors to prevent lease continuation as to ununitized portions which are nonproducing. We find nothing in the leases which confines the application of the Pugh clauses to surface areas and vertical divisions. It is common knowledge that leases are divided both vertically and horizontally and that unitization is ordinarily on the basis of a common source of supply. While the inclusion of all surface areas in consolidations protects lessors from the hardships resulting, in the absence of a Pugh *732clause, from partial vertical consolida-: tion, recognition of this fact does not solve the problem. A lease can provide for protection against continuation both of unconsolidated vertical divisions and of unconsolidated horizontal divisions. Considering thesef leases as a whole, we believe that a reasonable interpretation requires the conclusion that it was the intent of the parties to prohibit lease continuation as to unproductive portions without a consolidation whether such portions were the result of horizontal or vertical divisions. As the below-sea-level horizons were not included within any consolidations and as there was no production therefrom, the leases terminated as to such horizons at the end of the primary period.
In Nos. 6522 to 6548, inclusive, the judgments are severally reversed with directions to enter judgments for the plaintiffs cancelling the leases so far as below-sea-level horizons are concerned.
. The Commission order is not set out in full in the record but it apparently affected only gas production from above-sea-levol horizons. It is so treated by the parties.
. Cowman v. Phillips Petroleum Co., 142 Kan. 762, 51 P.2d 988, 991.
. Whitaker v. Texaco, Inc., 10 Cir., 283 F.2d 169; Panhandle Eastern Pipe Line Company v. Isaacson, 10 Cir., 255 F.2d 669; McCammon v. Texas Company, D.C.Kan., 137 F.Supp. 256; 2 Summers Oil & Gas, Perm.Ed., § 302.1, pp. 293-294 and cases cited in note 98.15.
. Cf. Broussard v. Phillips Petroleum Company, D.C.La., 160 F.Supp. 905, 907, affirmed per curiam on basis of opinion below, 5 Cir., 265 F.2d 221.
. In. eacb lease the habendum clause reads thus: “This lease shall remain in force and effect for a term of ten (10) years from the date of its delivery (hereinafter sometimes called the ‘primary term’) and as long thereafter as oil, gas, or other minerals are or can be produced from any well on said premises and as long as hereinafter otherwise provided in the event of consolidation.”
. Hoffman, Pooling and Unitization Clauses in Oil Leases, 1 Rocky Mountain Mineral Law Institute, pp. 107-108; Summers, supra, Vol. 3, § 553.1; cf. Carter Oil Co. v. McCasland, 10 Cir., 190 F.2d 887. See 1959 Supp. to G.S. Kan.1949 §§ 55-603 and 55-703 which respectively empower the state corporation commission to regulate the taking of oil from any pool and of gas from any common source of supply.
. Cf. Whitaker v. Texaco, Inc., supra, 283 F.2d at pages 176-177.
. Hoffman, supra.
. Cf. Wilson v. Texas Company, 147 Kan. 449, 76 P.2d 779, 783.
. Summers, supra, Vol. 3, § 512, p. 403.