Two initiatives aimed at curbing attempts to restrict oil and natural gas development have garnered more than half the signatures required to appear on the Nov. 4 ballot, a group formed to support energy development said Tuesday.

Initiative 121 has more than 55,000 signatures, while Initiative 137 has more than 59,800 signatures, according to Protecting Colorado's Environment, Economy and Energy Independence. The initiatives must attain 86,105 signatures by Aug. 4 to appear on the ballot.

Funded by oil and gas companies, the political issue committee is behind efforts to gather the signatures.

Anadarko Petroleum Corp. (NYSE: APC), Noble Energy Inc. (NYSE: NBL), the two largest producers in Northern Colorado, and other oil companies formed the committee to support and oppose various ballot initiatives that affect the industry.

The committee received $2.6 million in contributions and spent $2.2 million, according to a July 1 report filed by the committee with the Colorado Secretary of State's office. It reported more than $3 million in cash on hand.

Initiative 121, spearheaded by Rep. Jerry Sonnenberg, R-Sterling, would bar cities and towns that have banned hydraulic fracturing from receiving tax revenue generated by oil and gas development elsewhere in the state. In 2012, the oil and gas industry in Colorado contributed nearly $1.6 billion in revenue to state and local governments, school districts and special districts, according to a study by the Leeds School of Business at the University of Colorado-Boulder.

Known as fracking, the drilling technique involves pumping liquid down a drilled hole to extract oil and gas from tight shale formations. Voters in Fort Collins, Longmont, Lafayette, Broomfield and Boulder have passed bans on fracking, while Loveland voters defeated a two-year moratorium on fracking last month.

Initiative 137 would require a petition circulated for signatures to mention an initiative's estimated fiscal impact. Proponents of an initiative would have to prepare the fiscal impact estimate, which would be subject to review by the state Legislative Council.

Activists have submitted competing ballot initiatives to restrict hydraulic fracturing.