[T 1] In 1968, thе landowners, who owned both the surface and mineral estate in certain Campbell County property, leased their ranch for oil and gas development. Production occurred, and the lease remained held by that production. The landowners deeded the surface of the ranch and "coal and minerals commingled with [the] coal" to a neighboring coal mine operator in 1974, reserving all "oil, gas, and other minerals" not otherwise conveyed. Twenty years later, development of the gas found within the coal, known as "coalbed methane," became commercially feasible. A coalbed methane operator obtained an assignment of the oil and gas leasehold rights from the surface to a depth of 1,000 feet and began development of the coalbed methane. The successors in interest to the landowners claimed their right to royalties on the coalbed methane; however, the coalbed methane operator paid all royalties to the coal operator. The landowners filed a complaint seeking a declaratory judgment as to the ownership of the coalbed methane and recovery of the unpaid royalties. The district court granted summary judgment in favor of the coal operator. We reverse.
ISSUES
[¶2] The Morgan Mineral Heirs present the following issue for our review:
Do deeds which grant:
*542 All coal and minerals co-mingled with coal that may be mined or extracted in association therewith or in conjunction with coal mining operations
But reserve:
All oil, gas and other minerals except as set forth above
Convey coal bed methane gas, or not?
RAG Wyoming Land Company (RAG) restates the issue as: "Was the district court correct in granting summary judgment to Appellees by ruling that coalbed methane gas was conveyed by Appellants through the warranty deeds?" Hi-Pro Production, LLC (Hi-Pro) phrases the issue as:
Do warranty deeds which grant "all coal and minerals commingled with coal that may be mined or extracted in association therewith or in conjunction with such coal operations" and which reserve "all oil, gas and other minerals except as set forth above" convey coalbed methane gas ("CBM") as produced from the Wyodak coal seam?
FACTS
[¶3] In 1968, Alfreda M. Morgan and Norvin D. Morgan, Sr. (landowners), the owners of the surface and mineral estate in certain lands in Campbell County and descendants and heirs of the original homesteaders, gave an oil and gas lease to W.R. Gibson, doing business as Powder River Oil Company, granting him the right to produce "oil, gas, and casinghead gas, and other minerals" and retaining a one-еighth royalty interest in the oil and "the proceeds from the sale of the gas, as such, for gas from wells where gas is found." Production occurred on those lands, and royalties were paid to the landowners. In 1971, Meadowlark Farms, Inc. (Meadowlark), predecessor in interest to RAG (coal operator), began surface coal mining operations on state and federal coal leases in the area. In 1974, Meadowlark entered into an Option to Acquire Real Property with the landowners which granted an option for it to acquire the landowners' ranch which consisted of approximately 1,560 acres together with "all coal and minerals co-mingled with coal owned by SELLERS." The landowners owned the coal under approximately
200 acres of the property. The option also provided that, upоn execution, the landowners were entitled to lease the surface for farming and ranching purposes upon payment of a sum equal to the assessed property taxes. Meadowlark exercised the option and purchased the property. The warranty deed conveyed the lands and "all coal and minerals commingled with coal that may be mined or extracted in association therewith or in conjunction with such coal operations" and reserved to the grantor "all oil, gas and other minerals except as set forth above."
[¶4] Oil and gas production, coal mining, and ranching proceeded simultaneously without dispute, and the landowners received the royalties from all oil and gas production. At some point in time, the oil and gas lease was assigned to Torch Energy Advisors (Torch). In the еarly 1990s, techniques for the production of gas found within the coal seam, or coalbed metHane, were developed and became commercially feasible. Although unclear from the record, it appears that, by 1997, production of coalbed methane had begun with six wells located on federal coal lands and two wells located on the lands subject to the landowners' oil and gas lease. Upon learning of the coalbed methane wells in 1997, Marshall Morgan, one of the heirs of the landowners, wrote a letter to Torch informing it of his interest in the oil and gas and demanding his share of the royalty payments. On the basis of Mr. Morgan's claim, Torch began escrowing the royalty payments which apparently it had been previously sending to the coal operator. As of September 1998, a total of $106,682.09 had been escrowed. Ultimately, RAG, the coal operator, and Torch entered into an indemnity agreement wherein RAG agreed to indemnify Torch from all liability in exchange for its agreement to resume making royalty payments to RAG. Torch assigned a portion of its interest in the oil and gas lease from the surface to 1,000 feet beneath the surface to Hi-Pro effective May 1, 2000.
[¶5] RAG entered into two surface use licenses and agreements for coalbed methane development with Hi-Pro which provided for coordination in the development of the coal and coalbed methane resources. In the *543 agreement applicable to the lands subject to the landowners' oil and gas lease, RAG claimed "legal rights in certain coalbed methane gas wells, locations, [and] leases." In exchange for RAG's аllowing Hi-Pro access to the area, Hi-Pro agreed to pay RAG forty percent of the market value of the gas produced and agreed its rights were "subordinate to and subject to the continuous and uninterrupted right of RAG ... to mine coal and conduct surface coal mining operations." In the agreement applicable to other lands-presumably the federal coal lands, Hi-Pro agreed to a similar subordination of its interests and a much lower price of one and three-quarters percent on gas from the Wyo-dak coal seam and two percent on coalbed methane produced from any other coal seam. The agreements also provided for lengthy, detailed procedures and obligations to ensure the coalbed methane development did not interfere with RAG's cоal mining operation.
DISCUSSION
[¶6] The existence of coalbed methane has been well known for over a century. Paul N. Bowles, Coalbed Gas: Present Status of Ownership Issue and Other Legal Considerations, 1 Eastern Min. L. Inst. § 7.03 (1980). In fact, flash fires occasionally occurred on drilling rigs for many years when wells were drilled through the coal seam, and ventilation of underground mines was necessary to prevent fires and explosions. Michelle D. Baldwin, Book Note, Ownership of Coalbed Methane Gas: Recent Developments in Case Law, 100 W. Va. L.Rev. 673 (1998). Historically, coalbed methane "had long been considered a dangerous waste product of coal mining." Amoco Production Co. v. Southern Ute Indian Tribe,
[¶7] In the 19708, the value of coalbed methane was recognized, and government grants became available to encourage its development. Id. In 1981, the Solicitor of the Department of the Interior issued an opinion addressing the ownership of coalbed methane in federal coal deposits concluding the reservation of coal to the United States in patents issued after 1909 did not include coalbed methane. In reliance on that opinion, oil and gas operators began entering into leases to develop coalbed methane with individual landowners who owned the oil and gas. Id. In the early 1990s, techniques for efficient development of coalbed methane, specifically within the coal deposits in the Powder River Basin in Wyoming, were perfected. In 1991, litigation ensued between the federal government and certain Indian tribes which claimed the government's reservation of coal in 1909 and 1910 included the coalbed methane on lands originally owned by the government which now belonged to them. Ultimately, that issue was resolved when the United States Supreme Court held coalbed methane was not included within the reservation of coal and overruled district and eireuit court decisions which had concluded coalbed methane was owned by the owner of the coal. Id. at 874.
[¶8] Commercial development of coalbed methane in the Powder River Basin began in the early 1990s. Prior to that time, coalbed methane escaped from the coal in the course of the open pit surface mining process, and ro attempt was made to capture that gas as a valuable resource.
[¶9] A brief discussion of the chemistry and the composition of methane and coal is in order. Coalbed methane is chemically identical (CH,) to gas producеd through conventional methods, and each is known as "natural gas." Methane or natural gas originates from the decay of organic material over time under great pressure and temperature. Whether that process occurs in coal deposits or at greater depths, the result is the same-natural gas is produced. The process which transforms organic material into coal is known as coalification.
The coalification process generates methane and other gases. Because coal is porous, some of that gas is retained in the coal. CBM gas exists in the coal in three basic states: as free gas; as gas dissolved in the water in coal; and as gas "adsorbed" on the solid surface of the coal, that is, held to the surface by weak forces called van der Waаls forces. These are the same three states or conditions in which gas is stored in other rock formations. Because *544 of the large surface area of coal pores, however, a much higher proportion of the gas is adsor[bled on the surface of coal than is adsor[bled in other rock. When pressure on the coalbed is decreased, the gas in the coal formation escapes.
Id. at 873 (citations omitted).
[¶10] Natural gas or methane, whether located in a sandstone reservoir or a coal seam, is produced by creating a pressure differential between the well bore and the reservoir. In the Powder River Basin, coalbed methane production involves the removal of water from the coal formation, which reduces the pressure and allows the gas to escape. Likewise, methane will migrate naturally from coal seams, as well as from other reservoirs, to other porous or permeable strata depending on pressure differentials.
[¥11] The issue to be resolved in this case is whether the parties to the deed in question intended the coalbed methane to be conveyed along with the coal estate or reserved to the grantor as part of the oil and gas estate. The parties agree the governing principle of contract construction is determination of the parties' intent from the language of the instrument itself. As we stated most recently in the context of interpreting a mineral conveyance:
"According to our established standards for interpretation of contracts, the words used in the contract are afforded the plain meaning that a reasonable person would give to them. When the provisions in the contract are clear and unambiguous, the court looks only to the 'four corners' of the document in arriving at the intent of the parties. In the absence of any ambiguity, the contract will be enforced according to its terms because no construction is appropriate." Amoco Production Company v. EM Nominee Partnership Company,2 P.3d 534 , 539-40 (Wyo0.2000) (citations omitted).
Assignments are contracts and are construed according to the rules of contract interpretation. The determination of the parties' intent is our prime focus in interpreting or construing a contract. If an agreement is in writing and its language is clear and unambiguous, the parties' intention is to be secured from the words of the agreement. When the agreement's language is clear and unambiguous, we consider the writing аs a whole, taking into account relationships between various parts. In interpreting unambiguous contracts involving mineral interests, we have consistently looked to surrounding cireum-stances, facts showing the relations of the parties, the subject matter of the contract, and the apparent purpose of making the contract.
Boley v. Greenough,
[112] We must first examine the terms of the deed and give them their plain and ordinary meaning. Wolter v. Equitable Resources Energy Company, Western Region,
[113] The language of the deed conveys "all coal and minerals commingled with coal that may be mined or extracted in association therewith or in conjunction with such coal operations" and reserves "all oil, gas and other minerals except as set forth above." The first term the parties argue must be interpreted is "minerals." We have little trouble concluding natural gas produced from the coal seam is a mineral under Wyoming law. Amoco Production Company v. Guild Trust,
[¶14] The determinative question is whether the parties intended "minerals commingled with coal that may be mined or extracted in association therewith or in conjunction with such coal operations" to include natural gas found in the coal seam. We are unable to discern any unique meaning of "commingled" in the context of minerals. The word "commingle" is defined by Webster's New World Dictionary as "to mingle together; intermix; blend." Webster's New World Dictionary 285 (2nd C. ed.1972). The term does not suggest any sort of chemical change must occur to constitute commingling but only a mixing together. Given the three states of coalbed methane as free gas within the cleats and matrixes of the coal, gas dissolved in water in the coal pores, and gas adsorbed onto the solid surface of the coal, it appears to be "mixed together" with the coal within the meaning of the terms of the deed.
[T15] In addition to being commingled with the coal, the other "minerals" conveyed must be those that "may be mined or extracted in association" with the coal or "in conjunction with such coal operations." Likewise, these terms must be given their plain and ordinary meaning to reasonable persons at the same time and place of their use; i.e., 1974 in the Powder River Basin of Wyoming. The coal operator argues that production of gas has been considered "mining" relying on Coronado Oil Company v. Grieves,
[¥ 16] Is the plain meaning of "extracted" the same as "released," "escaped," or "ventilated"? It is obvious these words connote different actions, and the distinctions between them are crucial to determining the intent of the parties to this deed. Webster's New World Dictionary confirms that difference by defining (1) "extract" as "to draw out by effort; pull out" and "to remove or separate (metal) from ore"; (2) "release" as "to set free"; and (8) "ventilate" as "to provide with an opening for the escape of air, gas, etc." 1 Under the plain meaning of the terms chosen by the parties to the deed, we cannot conclude they intended to include coalbed methane gas as a mineral "mined or extracted in association therewith or in conjunction with such coal operations" when it can only be produced through wells as any other gas.
[T17] We could end the inquiry at this point. However, because of the importance of the issue of the ownership of coalbed methane in general and the extensive consideration of this issue by other courts and commentators which we find helpful and consistent with our initial conclusion, further discussion is warranted.
[T18] The coal operator poses a creative argument suggesting that, because coalbed methane can most efficiently be produced in advance of the mining operations thereby *546 reducing the water the mine must contend with and making the mine more economically successful, it is mined or extracted "in association therewith" or "in conjunction with" coal mining operations. Two problems exist with that argument. First, the gas production does not occur automatically in the process of overburden and coаl exeavation and removal. Instead, it only occurs when and if the coal operator decides to undertake gas well drilling in advance of the mine face. Second, such "mining" techniques-the coordination of well drilling and mine exeavation-did not exist until twenty years after the deed in question was drawn which poses the broader question in this case. How is the parties' intent to be determined when minerals become valuable long after a conveyance by (1) discovery of new methods of production; (2) changes in economics making production of a previously known, but unwanted, mineral profitable; (8) or discovery of the presence of minerals not previously known to exist? Obviously, the language of the particular documents involved affects the answer to this question on a case-by-case basis.
[¶19] In this partiсular case, no reference is made in the deed to coalbed methane, and no other language can be said to address the parties' specific intent with regard to it. In civreumstances like those present here, a search for the parties' specific intent produces little fruit because the identity, value, or feasibility of production was unknown to the parties at the time of the conveyance and, therefore, they likely had no intent at all with regard to the substance in question. Consequently, we must focus upon the general intent of the parties, concentrating on the "purposes of the grant in terms of respective manner of enjoyment of surface and mineral estates." Comment, New Values Under Old Oil and Gas Leases: Helium, Who Ouns It?, 62 Mich. L. Rev. 1158, 1169 (1964).
The intention sought should be the general intent rather than any supposed but unexpressed specific intent, and, further, that general intent should be arrived at, not by defining and re-defining the terms used, but by considering the purposes of the grant or reservation in terms of manner of enjoyment intended in the ensuing interests.
Eugene O. Kuntz, The Law Relating to Oil and Gas in Wyoming, 3 Wyo. L.J. 107, 112 (1949). It can be said this approach would favor the conclusion that the coalbed methane, which unquestionably has the chemical composition of gas, belongs to the gas owner who is entitled to recover all gas beneath the surface wherever found unless, of course, specifically limited by the original conveyance. Edward A. Craig, III & Marlee S. Myers, Ownership of Methane Gas in Coalbeds, 24 Rocky Mtn. Min. L. Inst. 767 (1978). However, the coal owner argues that, because the gas is located within the coal seam, its right to mine, and thereby ventilate or waste the coalbed methane, implies ownership. Consequently, the court is faced with determining whether that right is tantamount to ownership or simply incidental to the right to mine. Id. at 784.
'{120] Coalbed methane ownership has been the subject of litigation for the last twenty years in a variety of forums with differing results. 1 Howard R. Williams & Charles J. Meyers, Oil and Gas Law § 219 at 274.5 to 274.10 (2000). As noted in the most recent and thorough discussion of this issue, "[t]he conflicting legal principles and the existing precedent ... do not point toward any one of these solutions as necessarily or even probably correct, so a court could adopt any one of the approaches described below." Jeff L. Lewin et al., Unlocking the Fire: A Proposal for Judicial or Legislative Determination of the Ownership of Coalbed Meth-ame, 94 W. Va. L.Rev. 568, 614 (1992). While no other case is on all fours with the facts herein, the approaches taken by other courts provide insight and guidance to our deliberations. The earliest case occurred in Pennsylvania and favored the coal owner relying on the "ownership in place" theory of oil and gas ownership and on the specific language of the conveyance which reserved to the gas owner only the "right to drill and operate through said coal for oil and gas." Hoge,
[¶21] In Alabama, the courts have had several opportunities to consider the dispute over ownership of this mineral resource. Where the document reserving the oil and gas was "subject to the requirеment that all coal seams located in said lands penetrated in such exploration or drilling operations shall be encased or grouted off," the court had no difficulty concluding the parties intended to separate the coalbed methane from the rest of the oil and gas present in other formations. Rayburn v. USX Corp., Civ. No. 85-G-2661-W,
[¶22] Despite these distinctions, the Alabama Supreme Court found that a deed, which granted "all the coal and connected mining rights" but reserved "all of the gas," conveyed the coalbed methane located within the coal seam. However, it did not include gas which had escaped into the material left after longwall mining was completed (the "gob zone"). The court seemed focused upon the bundle of property rights incident and necessary to the recovery of the coal and the potential for interference with those rights in the facts of that case. 2 At the same time, the court found
no scientific or legal basis to support the proposition that coalbed methane gas should be treated as a resource separate and distinct from other natural gas, or from any other gas. The fact that the coalbed methane gas is produced by, and stored within, coal seams does not require the conclusion that a grant of "all coal" includes coalbed methane gas, nor does it require the conclusion that a reservation of "all gas" does not include coalbed methane gas.
NCNB Texas National Bank, N.A.,
"Given their awareness of the presence of coalbed gas in the stratum, the earlier described similarities between coalbed gas and what has commonly been referred to as 'natural gas', and the fact that the unrestricted term 'gas' was employed in the reservation clause, we believe the plain meaning of the term 'gas' would be too far subverted were we to exclude coalbed gas as a recoverable gas."
Id. at 226 (quoting Hoge,
[¶23] In contrast, the Montana Supreme Court reached the opposite conclusion that the conveyance of "all coal and coal rights" did not include coalbed methane but did so by relying on the same ownership in place theory of oil and gas ownership which the Pennsylvania court utilized to arrive at the opposite conclusion in Hoge. Carbon County v. Union Reserve Coal Co., Inc.,
[¶24] Struggling to articulate clear rules for the resolution of this difficult issue, the courts, especially when these cases are considered together, displayed confusing and inconsistent reasoning. While lip service is paid to the role of the theory of ownership of oil and gas in the respective jurisdictions, the ultimate rulings do not depend on which theory of ownership applies. In both ownership in place and rule of capture jurisdictions, courts have concluded the gas owner is entitled to all the gas it can capture, yet the coal owner owns the coalbed methane. We agree with those courts and commentators which have rejected reliance upon the nature of the ownership interest in oil and gas to resolve this question. Lewin, 94 W. Va. L.Rev., supra at 563. In addition, neither rule of ownership has been clearly adopted by this court to date, nor has the distinction been considered of any significant legal consequence. Mark W. Gifford, The Law of Oil and Gas in Wyoming: An Overview, 17 Land & Water L.Rev. 401, 404 (1982). 3
[¶ 25] The most recent ruling on the issue of ownership of coalbed methane involved determining the intent of Congress in reserving "all coal" from lands patented under the Coal Lands Acts of 1909 and 1910. Reversing the Tenth Cireuit Court of Appeals, the United States Supreme Court ended a long running controversy over ownership of coalbed methane in federal coal deposits.
4
In doing so, the court did not follow the confusing array of state court cases and relied instead upon the plain meaning of the terms at issue to conclude Congress did not intend the term "coal" to include coalbed methane. Southern Ute Indian Tribe,
[¶26] The Supreme Court looked to dictionary definitions which defined coal as a solid fuel resource and methane as a distinctly separate substance. Id. at 874,
As these dictionary definitions suggest, the common understanding of coal in 1909 and 1910 would not have encompassed CBM gas, both because it is a gas rather than a solid mineral and because it was understood as a distinct substance that escaped from coal as the coal was mined, rather than as a part of the coal itself.
*549
Id. at 874-75,
[¶27] At bottom, our role is to give effect to the general intent of the parties to the conveyance with regard to the exploitation of the mineral resources. Rather than following some rigid rule of law, we believe this issue should be governed by the facts and cireumstances surrounding the execution of this warranty deed. This approach is consistent with that taken by other courts and recognized by the commentators as the most practical one. Lewin, 94 W. Va. L.Rev., supra at 638.
[¶28] In the case before us, we know the purpose of the mining company's purchase of thе property was to allow the development of a surface coal mining operation. On the other hand, the landowners were fully aware that their property had value for its gas development as they had previously leased their oil and gas interest and had received the benefit of royalty payments. Their purpose in executing the warranty deed was to realize additional value from the property through the sale of the surface and their limited coal rights. The general intent which can logically be ascribed to these parties is that the landowners would retain any oil and gas found within the property and the coal operator would be able to fully exploit the coal resource. Each of the parties involved in this situation-the landowners, the original gas lessee, the coalbed methane operator, and the coal owner-operated consistently with this intent. The landowners, acting as the owner of the gas resource, leased all the right to produce oil and gas on the property with no distinction as to depth or source of the gas. The original oil and gas lessee proceeded to drill and produce, without distinction as to depth or source, all oil and gas found in the conventional manner. Twenty years later, when coalbed methane production became commercially feasible, the coalbed methane operator obtained an assignment of the oil and gas lease from the surface to 1,000 feet beneath the surface, under the obvious assumption that the coalbed methane was covered by the lease. And, for over twenty years, the coal owner operated its surface mine, venting whatever gas existed within the coal as it was mined, without objection or interference. To conclude that the landowners intended to separate the coalbed methane and convey it along with their outstanding royalty interest through the language of "all coal and minerals commingled with [the] coal" is simply not plausible.
[¶29] The coal operator argues it intended to acquire all minerals that were commingled with the coal in order to eliminate the possibility of conflicts between the development of those minerals and its mining operation. While that would be a logical conclusion to be drawn in the abstract, the potential conflict with oil and gas development would certainly not be averted in this situation by the coal owner also owning the private coalbed methane in a relatively small area of the mine, as conventional ofl and gas development already existed throughout the mine area and the coal operator did not own the federal coalbed methane which existed throughout the majority of the mine area. We also doubt conflicts with coalbed methane development per se, as distinct from other oil and gas development, were on the *550 coal owner's mind at the time of the warranty deed since commercial development of that resource did not exist in this area.
[¶30] The coal operator strenuously argues the broad language of the warranty deed, "coal and minerals commingled with [the] coal," was intended to allow it to release the coalbed methane during the mining operаtion without liability. However, as noted by the Supreme Court:
The right to dissipate the CBM gas where reasonable and necessary to mine the coal does not, however, imply the ownership of the gas in the first instance. Rather, it simply reflects the established common-law right of the owner of one mineral estate to use, and even damage, a neighboring estate as necessary and reasonable to the extraction of his own minerals.
Southern Ute Indian Tribe,
[¶31] While we recognize that separate ownership of coal and coalbed methane may result in conflicts, we agree with the United States Supreme Court when it noted "[that is not the issue before us, however. The question is one of ownership, not of damage or injury," Southern Ute Indian Tribe,
CONCLUSION
[132] On the basis of the unambiguous language of the deed and the surrounding facts and cireumstances, we conclude the parties generally intended the coal to be conveyed and the gas, wherever it may be located within the property, to be reserved to the landowners. Coalbed methane, being a gas, remained the landowners' property. By this ruling, we do not intend to imply that, in all circumstances, the conveyance of coal excludes the conveyance of the coalbed methane. Parties can certainly sever the coalbed methane from the remainder of the oil and gas estate and convey it seрarately. Such an explicit severance occurred in this case when the oil and gas lessee vertically segregated its oil and gas leasehold interest and assigned from the surface to 1,000 feet beneath the surface, which contained the coal seam, to Hi-Pro. However, the warranty deed from the landowners to the coal operator in this case, which conveyed "all coal and minerals commingled with coal that may be mined or extracted in association therewith or in conjunction with such coal operations"
*551 but reserved all oil and gas, did not accomplish such a segregation.
[¶83] Reversed.
Notes
. The referenced definition of "ventilate" is one of several definitions but was chosen as the most appropriate to the circumstances of this appeal.
. This dispute arose ovеr an underground mine where coalbed methane was produced through both horizontal and vertical wells which were hydrofractured to enhance production and wells drilled into the mine area after longwall mining was completed and subsidence created a "gob" of rubble into which coalbed methane collected. NCNB Texas National Bank, N.A.,
. Mr. Gifford notes: "UKimately, the determination of whether nonownership theory or ownership in place theory applies to interests in oil and gas in Wyoming is of small consequence" and provides as authority for that conclusion 1 Howard R. Williams & Charles J. Meyers, Oil and Gas Law § 203.1 (1981). Gifford, 17 Land & Water L.Rev., supra at 404.
. Only 200 acres of the coal owner's surface mine in this case involved private coal. The remainder, and the vast majority of the coal, consisted of federal coal. Consequently, pursuant to the Southern Ute Indian Tribe case, in most of the mine in this case, the coalbed methane is not owned by the coal owner.